A small DIY air purifier - <AUTHOR> https://github.com/Kels316/DIY-Air-Purifier <comment><USER2> Air quality test before and after or it doesn't work.

I am very suspicious with regards to air purifiers. Have you ever seen real HEPA filter? It is thick and it is quite difficult to push air through it. I can't imagine small PC fan that is designed to push air through UNOBSTRUCTED space will make any significant flow of air. I have spent some time with the guys who build PCs and who know great deal about fans and one thing I learned even an object that the air has to pass around or any kink in the path of air can severly impact performance of PC fan. Because they are designed to be quiet and still provide good flow of air they produce almost no pressure differential to speak of and the flow can be halved by a wire mesh that is a bit too dense.

You need to cycle the air in your room through the filter couple of times to clean it, assuming your filter is any good.

The cheap fan in the picture would barely be able to cycle the air in a small room maybe once an hour, if it was completely unobstructed. It is very likely that with any kind of HEPA filter the flow will drop by an order of magnitude.

Go with suggestion of other readers. If you want good, cheap filter, use a box fan and especially one that was designed to give good pressure difference. Take large cardboard or plastic box and mount large HEPA filter in it so that the air has to pass through. The larger the surface of the filter the easier time the fan will have to push the air through it and more efficient it will be.

<comment> 0-_-0 > Because they are designed to be quiet and still provide good flow of air > they produce almost no pressure differential to speak of and the flow can be > halved by a wire mesh that is a bit too dense

There are high static pressure fans which address this problem, specifically designed to work with pressure differential, usually used to blow air through radiators for water cooling. The fan linked in the github page (Noctua NF-F12, the "cheap fan" in the picture) is such a fan, it provides a static pressure of 7.63 mmH2O, which is very high.

Edit: you can get regular-sized 12cm pc fans that need 48 watts and rotate at 7160rpm, move 7.160 m^3/min air at 35.877 mmH2O static pressure:

[https://www.frozencpu.com/products/8147/fan-500/Delta_Mega_F...](https://www.frozencpu.com/products/8147/fan-500/Delta_Mega_Fast_120mm_x_38mm_Fan_-_252_CFM_- _Bare_Lead_PFB1212UHE-F00_No_RPM.html?tl=g36c435s1109)

<comment><USER3> > it provides a static pressure of 7.63 mmH2O

If anyone else is wondering, that's about 0.8 mbar (roughly 8 ten-thousands of an atmosphere), or 80 Pa of over-pressure.

To put this into perspective, my local atmospheric pressure varied about 2000 Pa in the last 48h due to weather changes.

<comment><USER4> Lemme go send my air intake through a time machine and as long as the weather keeps changing we can use that to drive air through a filter!

<comment><USER3> No need for a time machine (or being snarky - I did say it's just for comparison, didn't I? I think it does put the "very high pressure" into perspective)

That said, your time machine idea could be simply implemented with a large, airtight box. Simply put the filter over it and weather changes will push and pull air through the filter with two orders of magnitude more pressure than this little fan. Volume of filtered air will depend on the volume of the box though, so better get a large one.

</comment></comment></comment></comment></comment><comment><USER5> This is a really cool project but frankly you can do it a lot cheaper. Find the cheapest box fan you can find, and find the cheapest HEPA filter you can, and strap the HEPA filter to the front. To improve air purification even futher, slap an activated carbon filter on the front too, and your air purifier now filters VoCs! For cheap Activated Carbon Filters, look into the kind used for Aquarium filters. They'll work just as well for air as far as I know.

In China there is a whole company founded on doing just this, although they've since pivoted into selling specific air purification hardware at a significant discount. See: [https://smartairfilters.com/cn/en/product/diy-1-1-air- purifi...](https://smartairfilters.com/cn/en/product/diy-1-1-air-purifier/)

<comment><USER6> If you want this to actually work, you take a box fan, and 2 filters. You make a triangle and then some cardboard on the top and bottom to fill the gap. This increases surface area and reduces the stress on the fan due to pressure drop. Slapping a filter directly on to the box fan is going to kill the fan very quickly. [https://i.imgur.com/SX1RloH.jpg](https://i.imgur.com/SX1RloH.jpg)

<comment><USER7> I ran a few cheap box fans with filters directly over them for several years and none of them failed, I have heard this claim a lot but it seems overstated. The triangle setup _will_ significantly increase the airflow and thus the effectiveness of filtration though.

<comment><USER6> I guess it depends on the quality of filter. If you're rocking a high merv filter for smoke the pressure drop can be significant.

</comment></comment></comment></comment><comment><USER8> May as well ask here: do air purifiers have meaningful health benefits for generally healthy people? I get that you change the filter and it's filled with grey muck and that's gross, and that the filters change particulate content in air, but is there good evidence that doing those things improves health if you don't already have some sensitivity to air pollution or live in a highly polluted area?

I don't know if "Lung India" is a great journal, but the "Efficacy of indoor air filters" section of this paper [1] doesn't offer much support. All studies are pretty small and focused on people with asthma or pet allergies. The few studies of populations without such conditions show what look to me like minor improvements, e.g. a ~5 mmHg drop in blood pressure. These aren't super strong studies though.

The argument that pops up in pro-air-filter pieces draws a line through "air pollution can be a big health hazard" (true), "air filters reduce some particulate content in the air" (true), and "air filters improve health" (unclear). But the "big health hazard" conclusion seems to come from intensely polluted environments, like poorly-ventilated homes that use kerosene, or areas with lots of smoke. For a generic first-world home I can't find much evidence.

[1] [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587002/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587002/)

<comment><USER9> I would assume the majority of people (in the US, anyway) are already filtering their air enough through their central air to make any additional "room-sized" filtering negligible.

Similarly they make some very dense HVAC filters if standard ones aren't catching the level of particles you need, so I'm not sure what the purpose of these filter-fan things are for _most_ people.

<comment><USER10> >Similarly they make some very dense HVAC filters if standard ones aren't catching the level of particles you need, so I'm not sure what the purpose of these filter-fan things are for most people.

These are a scam, especially all those 3M filtrete ones. Air handlers in homes and most other HVAC applications are not made to also serve as tiny particulate filters, so it will make the whole HVAC system slow or even stop since it won't be able to get the air flow it needs to function.

<comment><USER11> I believe you that the HVAC isn't designed for such a filter. But a few months back my home was in the path of smoke from some wildfires. The AQI went from 200 to 0 after I installed a filter and ran the house fan for an hour. Also, the furnace doesn't have to work very hard here because of the mild climate, so I never have much of a heat bill anyway. It would be a bummer if the furnace died because of it running out of spec, but I'm skeptical that the risk-adjusted cost of that is higher than the cost of standalone filtration units.

<comment><USER10> This page has a decent explanation of the problem:

[https://www.pvhvac.com/blog/whats-the-best-air-filter-for- yo...](https://www.pvhvac.com/blog/whats-the-best-air-filter-for-your-home)

All the commercial HVAC technicians I speak to say to use the cheapest non fancy filters if your goal is to maximize life of the HVAC system, but I'm sure it all depends on everyone's specific system and how the return is and whatnot.

</comment></comment></comment></comment></comment><comment><USER12> This seems like useless toy.

You should be aiming for something larger that would work for an apartment.

[1] [https://youtu.be/kH5APw_SLUU](https://youtu.be/kH5APw_SLUU)

[2] [https://youtu.be/8Hkdpx-59kk](https://youtu.be/8Hkdpx-59kk)

There is thousand vidoes on Youtube on how to DYI one.

<comment><USER13> The problem for areas presently affected by high PM2.5 concentrations, most notably Australia, is that materials which are commonplace in the US, box fans, but especially box-fan-sized square HEPA furnace filters, are rare as hen's teeth.

So alternate designs using available materials are required.

(Or someone might drop ship a few containers worth of box fans and HEPA furnace filters down under.)

<comment><USER14> Same problem here. I've just spent close to an hour trying to locate a box fan for sale in Europe, couldn't find any resembling those I can easily find on amazon.com!

</comment></comment></comment><comment><USER15> I don't know how effective they are compared to these devices, but I much prefer to keep plants with air purifying qualities. NASA did a study on a variety of air purifying plants in 1989: [https://ntrs.nasa.gov/search.jsp?R=19930073077](https://ntrs.nasa.gov/search.jsp?R=19930073077)

<comment><USER16> You would need to live in an indoor rainforest (approximately 680 plants for a typical house) to see an effect on air quality, a spider plant in the corner isn't doing anything: [https://www.youtube.com/watch?v=AmeiXikh0v8](https://www.youtube.com/watch?v=AmeiXikh0v8)

<comment><USER17> *to see a similar effect on air quality as mentioned in the study

</comment></comment></comment><comment><USER18> This project would take 2-3 days to filter the volume of air in a 1,000 sq foot apartment... which is to say it would do nothing of significance. To be effective, you want to change the air something closer to once every 30 minutes.

<comment><USER19> I agree that it would be silly to expect this thing to purify air for an entire living space.

With a few adaptations, however, it might be good as a soldering station fume extractor. These already exist and are little more than a tube, a fan, and a filter (usually with activated charcoal).

The nice thing about this one is that it's circular and could easily adapt to a flexible tube and you could perhaps stack fans for greater sucking power.

</comment></comment><comment><USER20> You could probably buy a box fan and tape a HEPA filter in front.

<comment><USER21> This works shockingly well. They were quite popular during last year's California fires when "real" air purifiers were sold out everywhere.

<comment><USER22> Also worked well in Seattle last summer.

</comment></comment></comment><comment><USER23> Is that little fan really effective? I just duck taped a furnace filter to a 20 dollar box fan. No 3d printer needed.

Just did this recently actually here's a pic [https://mobile.twitter.com/jonathanfly/status/12155378275654...](https://mobile.twitter.com/jonathanfly/status/1215537827565490176)

</comment><comment><USER24> Pollution sensors for indoor use that can be plug via USB to the mobile phone are really cheap, you can find laser ones like Nova SDS for $17 and some that are not so precise come even cheaper than that.

So unless the author buys a real PM2.5 sensor and does a test in a true room and not a box of the size of a Desktop PC, with the sensor on the opposite side of the room, and proves that the pollution drops to below 8micrograms/m3, in a reasonable time frame, than we can say that it is working.

Until than we can only say that the purifier is only able to purify a desktop PC.

</comment><comment><USER25> Not enough airflow to filter air. Really, it's just an expensive way to waste money.

Seriously? 600mA? Air purifiers are rated like 30W for a reason.

</comment><comment><USER26> I'm in Bangkok right now which is having a smog issue right now due to pollution and burning in the rice fields across the country. It's a shame that we're buying/making air filters instead of working on policy and cleaner methods of doing work--so now the poor and the wildlife can't afford to have clean air.

<comment><USER27> There are cleaner methods, stop taking the easy route and burning everything down.

</comment></comment><comment><USER28> In addition to the old "strap an HVAC sized air filter on the front of a box fan" tip, I'd add that it is important to maintain a positive air pressure in your living space. The only path air should enter your dwelling from the outside is via your air filter.

You can do this by putting the box fan in a window and sealing up any gaps with something like cardboard or thick plastic sheeting. On the outdoor end of the fan, put your filter. Close all other windows & doors in the house.

Keeping a positive indoor air pressure this way makes sure all the air in your house is filtered. Obviously you'll want to make sure your box fan's filter is rated for smoke / particulate matter.

<comment><USER13> Bad advice.

A decent filter's throughput is going to be multiples of your structure's air- exchange rate.

What you want to do is to _filter the interior air_ , by passing it, multiple times, through the filter. If you put the fan and filter in a window, you're hugely multiplying the air-exchange rate (to no net benefit), but are _filtering_ that air only once.

The net result is a much _higher_ indoor particulates level.

So no, don't do this.

<comment><USER28> Interesting perspective. Wouldn't it be best to do some combo of both? A low volume fan/filter that maintains positive pressure and an internal filter/fan combo?

I mean in labs and manufacturing facilities that need ultra pure air, I'm pretty sure they maintain a positive pressure inside the sensitive areas. Otherwise you'll be sucking in bad crap from every nook and cranny...

<comment><USER13> Various lab setups have different requirements.

For biocontainment you generally want _negative_ pressure, such that all _exhaust_ is filtered.

For clean rooms, positive pressure, to ensure filtration and minimum particle reduction levels within the conditioned space. These also have staged zones, much like a cascade refrigerator, with finer levels of purity as you approach the core. Humans themselves are excluded from the higher-purity zones (we're leaky bags of flakey skin, hair, dander, sweat, and mucus). Most especially in chip-fab, but also I suspect various nanofab facilities.

All of which is pretty much entirely outside my paygrade, so I can't really comment intelligently.

</comment></comment></comment></comment><comment><USER29> I would suggest worrying much more about PM2.5 and getting a filter that does trap those particles. Many health problems are caused specifically by small particulate matter.

<comment><USER30> His statement "I'm not concerned with the ability of the device to remove PM2.5" comes across as dismissive - he's not concerned because he's using a HEPA filter health officials are recommending and therefore he trusts it. HEPA starts at 0.3μm ("PM0.3") particle size, which doesn't cover finer forms of elemental carbon (soot). "H13" is a minimum retention efficiency though, not a specific particle size or application.

</comment></comment><comment><USER31> Here is similar idea: [https://www.aliexpress.com/item/32989809211.html?spm=a2g0o.p...](https://www.aliexpress.com/item/32989809211.html?spm=a2g0o.productlist.0.0.43497b069dZbSy&algo_pvid=2afaf365-792a-4bb2-9d1b-dcc2a10a062f&algo_expid=2afaf365-792a-4bb2-9d1b-dcc2a10a062f-0&btsid=7dc87566-75e8-4331-b4c7-07d5b6c2018c&ws_ab_test=searchweb0_0,searchweb201602_6,searchweb201603_53)

</comment><comment><USER32> How about a 'filter' that can 'wash' the air with clean water. To me it appears to me the best possible solution to clean air in a confined space. To put it simply, air can be bubbled through the clean water, to scrub it of both particulate and chemical contaminants. No doubt the apparatus will lend itself to several technical challenges like noise and the need for periodic changes of the water.

I believe such air purifiers already exist.

<comment><USER13> See: [https://venta-usa.com/product-category/airwashers/](https://venta- usa.com/product-category/airwashers/)

They do an excellent job of humidifying the treated space, which may or may not be ideal.

<comment><USER32> dredmorbius, do you own one? At what frequency do you normally change the water?

<comment><USER13> No, I don't. Ran across them discussing filtering options recently.

</comment></comment></comment></comment><comment><USER13> A group has come up with an alternative design, with a far higher flow rate, and similar in concept to US-based box-fan + furnace-filter designs (materials for which are _not_ readily available in Australia), with workshops in Canberra, described here:

[https://www.eventbrite.com.au/e/making-your-home-smoke- proof...](https://www.eventbrite.com.au/e/making-your-home-smoke-proof-diy- air-purifier-workshop-tickets-88598234705#)

Materials for DIY Air Purifiers are:

\- Floor Fan of any variety (BYO or we will be providing options for large and small fans)

\- PM2.5-suitable Air filter (we will be bulk ordering the best type of Ryco MicroShield Cabin Filters for this purpose)

\- Carboard & tape (we will provide these materials)

Efficiency of the US-based version seems to be quite good:

[https://invidio.us/watch?v=kH5APw_SLUU](https://invidio.us/watch?v=kH5APw_SLUU)

</comment><comment><USER33> What do you think about air washers? In addition to air filters, they blow air over wet surfaces to both clean and humidify the air.

Here is one from Phillips: [https://www.youtube.com/watch?v=n3xC3qxVphw](https://www.youtube.com/watch?v=n3xC3qxVphw)

<comment><USER34> I have one of those.

It does not "wash" the air. It has a HEPA-filter on the intake side before the humidifying cycle. So it is basically the same thing as all other examples on this comment page.

You can actually run it without water (which we do), then it does only filtration.

Don't buy this particular product. It is overprized and has dramatic production quality issues (we sent two back, amazon reviews indicate larger issues).

</comment></comment><comment><USER35> Speaking of air purifiers, does anyone have recommendations for one that is quiet and still effective?

I have a pair of Electrolux EAP300s, in small rooms.

Unfortunately on the lowest manual setting ("Quiet") they hardly do anything for air quality. And they're still louder than I like. I think they really optimized for cost; these devices feel very light and plasticy, the fan sounds cheap and has an uneven tone to it, and its speed keeps oscillating back and forth. The purifier itself is also not stable and it can make an annoying noise if placed on a surface that ends up vibrating along.

I also thought about DIYing one with noctua fans (which I know are quiet, and I have plenty of them in my PCs), but I suspect they're not going to be very effective.

<comment><USER24> It depends on what noise level is acceptable for you and the room size.

Out of 30 or so air purifiers available in shops here, of all the ones that are in the $100-500 category, the Winix P/U450 are able to push the largest amount of air under the constraint of <40db.

HEPA filters are rated at which air speed they are most effective and how much pressure is needed. The ammount of pressure will only rise as the filter is saturated with dirt. You need a sufficiently powerful fan, and fans that are both powerful enough and quiet enough are very expensive.

<comment><USER36> I have two Winix HR1000. They have extremely powerful blowers and are quiet when not in "turbo" mode. The turbo mode is actually pretty good for white noise when sleeping. I've been running them 24/7 for years now and they are still working great.

</comment></comment></comment><comment><USER37> Do air purifiers really work? I always have impression they're just sham, or at least placebo.

<comment><USER38> I felt similarly, but I have a family member who is bed-bound, there's some asbestos removal going on, so I decided to take the plunge.

I can vouch for their ability to detect impure air. If I start cooking anything, it switches on within seconds. It'll turn on within about three minutes of sweeping the floor. And if the detectors can turn on when the air is dirty, it stands to reason that they can tell when the air is clean and they turn off as well.

Shortly after getting this, some intriguing news surfaced regarding the installation of air filters in a California school (due to a gas scare) which resulted in a jump in test scores vs other schools in the same district.

I am not a scientist, but I'm feeling pretty convinced about the efficacy of these things.

[https://www.vox.com/2020/1/8/21051869/indoor-air- pollution-s...](https://www.vox.com/2020/1/8/21051869/indoor-air-pollution- student-achievement) [https://news.ycombinator.com/item?id=18219391](https://news.ycombinator.com/item?id=18219391)

<comment><USER38> (A few minutes after posting this, morning rooftop construction started. Sounds of saws and drills buzzing, large objects and beams being dropped directly overhead. Air purifier just kicked into high gear. Yes, I'm definitely into this thing.)

[https://thewirecutter.com/reviews/best-air- purifier/](https://thewirecutter.com/reviews/best-air-purifier/)

<comment><USER39> I'm a big fan of thewirecutter, and I reference them frequently on most things I'm buying. But for HEPA air filters, I don't feel like they test the models that I feel are best for someone with asthma, or other similar breathing problems.

We have several IQAir units, of at least a couple different models. None of them have sensors to automatically ramp up the filtering when they detect pollution, that would be nice. But according to the air quality sensors I have in the house, they do an amazingly good job of filtering the air, at least if you turn them up to high enough levels.

I have yet to see demonstrated clear benefit of the units with activated charcoal filters for removing VOCs from the air, but my gut feeling is they do help in those areas where VOCs are a concern. Not all parts of our house needs that, however.

Having four furballs does greatly increase the dander and other allergens we have to deal with, but we wouldn't give them up for anything, so the IQAir units at least make our lives a bit more livable. Especially during "Cedar Fever" season.

</comment></comment></comment></comment><comment><USER40> Nice.

For some strange reasons it immediately reminded me of the scene in Apollo 13:

[https://www.imdb.com/title/tt0112384/quotes/qt0476826](https://www.imdb.com/title/tt0112384/quotes/qt0476826)

</comment><comment><USER41> I use a box fan with filters taped to each side. You want to do both sides or the air gets pushed/pulled around the edges of the blades, rather than going through the filters.

<comment><USER13> That's doable, though you're increasing initial cost by about 1/3, and doubling consumables, by using two filters.

The net effective increased filtration rate is marginal.

If you can afford this without concern, it's fine, but it's not necessary.

<comment><USER41> It works with two and not with one, so pretty much required. The effect is far from marginal in my setup. Also far cheaper then the post link, less than half.

<comment><USER13> Numerous documented and tested builds with only one.

[https://invidio.us/watch?v=kH5APw_SLUU](https://invidio.us/watch?v=kH5APw_SLUU)

YMMV.

<comment><USER41> Cool, don't really care, happy with my double filtered setup

</comment></comment></comment></comment></comment><comment><USER42> My general theory is that HEPA makes sense for filtration where a single pass is all you get. So it makes sense for vacuum cleaners, air intakes, and such. But, for room air cleaning, what matters is the _rate_ at which particles are removed, not the cleanness of the air coming out. So, for recirculating, something like a MERV 13 filter seems like a better choice: it lets more particles through on each pass, but it also restricts airflow less.

<comment><USER13> PM2.5 particles are small enough that they pass through many materials.

You can use lower-efficiency (higher effective particle-size) filters ... but you'll just be blowing the bad stuff through them rather than removing it.

The net metric is _how fast the room particulate level drops_ , which is the treatment goal. Flow rate is a red herring.

<comment><USER42> That's why I suggested MERV 13 and not, say, MERV 8. If your filter removes a mere 50% of particles at a given size but moves twice as much air as a HEPA filter, you're doing fine for a recirculating filter.

</comment></comment></comment><comment><USER43> I'm all for DIY, but this looks horribly underpowered to do anything against major pollution.

I've got a Honeywell that's $150 and it must have 20-40x the throughput of this little thing.

[https://www.honeywellstore.com/store/products/honeywell-1700...](https://www.honeywellstore.com/store/products/honeywell-17000-s-quietcare- permanent-true-hepa-air-purifier-germ-reduction.htm)

</comment><comment><USER44> Has you tested it effectively can absorbe particles? It's a good project but seems more like a nice form to waste energy

</comment><comment><USER45> Pretty cool project.... Except for the fact that I cannot buy any of the parts from pccasegear. They deny certain geographical areas access to their website. In fact, this seems to be the new normal. Last week, I was denied access to a recipe from a .au website. Flipping on my VPN restores access..

</comment><comment><USER46> I've always wondered if you could essentially hook a blower up to a bong to filter particulates out of the air using water. Would be much cheaper to replace the 'filter', but I suspect it wouldn't filter as well. Seems like it could be an interesting tradeoff though.

<comment><USER13> There is a set of "Luftwascher" ("Air washer") designs which effectively do this.

These do filter out particulates, but also add enough humidity to the air that this is billed as a feature of the system. In high-humidity conditions this is less than ideal.

[https://venta-usa.com/product-category/airwashers/](https://venta- usa.com/product-category/airwashers/)

</comment></comment><comment><USER47> Is a filter or an ionizer better for smoke? [https://hackaday.com/2020/01/12/diy-ionizer-clears-the- air-o...](https://hackaday.com/2020/01/12/diy-ionizer-clears-the-air-on-a- budget/)

<comment><USER34> At least some of them don't really work at all. [https://www.youtube.com/watch?v=VM9CJZpqfpA](https://www.youtube.com/watch?v=VM9CJZpqfpA)

With something as simple and effective as HEPA-filters, it seems unreasonable to try other technologies.

</comment></comment><comment><USER48> I would say that there are electronic schemes and plans to build DIY ion air cleaners. They works nice to remove dust or tabacoo from air.

Also, ozone air purifier make wonders to keep at bay smells and fats (wonderful to have on the kitchen), and kills bacterias, spores and fungus.

<comment><USER24> Ozone is harmful.

<comment><USER49> It also smells bad too

<comment><USER50> That's very subjective - I quite like the smell.

</comment></comment></comment></comment><comment><USER51> Static pressure is important as well as airflow! Some info:

[https://www.engineersedge.com/filtration/hepa_filter_pressur...](https://www.engineersedge.com/filtration/hepa_filter_pressure_drop_considerations.htm)

</comment><comment><USER52> if you don't mind a noise you could buy a 2nd hand vacuum cleaner with a built-in hepa or water filter (ideally also with adjustable speed to make it less noisy) and just let it run without a hose, sucking the air and pushing it through the filter...

<comment><USER20> If you don't mind the noise and wasting a kilowatt on something that can be done with two dozen watts.

<comment><USER52> That kW will move you more air in 30 minutes than PC ventilator can in a whole day, especially if you're trying to push it through hepa filter which is fairly thick and adds quite a resistance.

</comment></comment></comment><comment><USER53> This basically looks like a mini Shop-Vac.

If you own a Shop-Vac (a wet-dry vacuum, generically), could you just turn it on without the hose? It would draw much more power, but presumably would work much quicker, and so may end up being more efficient.

<comment><USER54> Of course; ditto any vacuum cleaner, AC with filtration, etc.

It's just airflow + filter, which is why DIYing them is so popular.

</comment></comment><comment><USER55> Not sure what the point is when it costs $100 and is magnitudes smaller and less powerful than a proper one which runs at $200-300 - an upfront cost which is dwarfed in the long run by filter replacements, as would be the case here.

</comment><comment><USER56> there is also some other air filtering project on github. maybe a bit more powerful but more expensive and definitely more ugly. [https://github.com/KarstenSiemer/Open- Airfilter](https://github.com/KarstenSiemer/Open-Airfilter)

I don't really think airfilters in that size so much. They need to push a serious amount of air through the filters to be able to accommodate for natural air circulation. Some pc fans don't do the trick I'd suspect

</comment><comment><USER57> OP: Do you think [https://www.instructables.com/](https://www.instructables.com/) would have been a better place for this than Github.com ?

Great effort!

</comment><comment><USER58> Please don't use an iPhone X "for scale".

The dual-ruled calipers used in the next photo would be an acceptable substitute for just using a plain old ruler.

<comment><USER59> Most people know what an iPhone X (or similar device) feels like. Not many people have held calipers (or remember what holding them feels like) and not many people can put into context what a marking on a ruler actually means.

For a quick scale judgment, a smartphone is perfect. It's not supposed to be precise.

<comment><USER58> I respectfully disagree. Smartphones do not come in a single standard size. Using them as comparisons will end up with the same problem as using coins or banknotes--it is only helpful for those already familiar with the specific comparison item.

A "for scale" comparison is most useful with a metric-scale ruler. Metric lengths are standard worldwide. Including an inch-scale ruler may help US- based persons. The calipers were useful inasmuch as they had a metric length scale etched into them--a ruler with extra bits.

By your argument, it is acceptable to report large lengths or areas in multiples of US football fields, volumes as multiples of Olympic-size swimming pools, or database sizes in multiples of the entire literary content of the US Library of Congress. Journalists do this frequently, and every time, it drives me absolutely bonkers (an aggravation level equivalent to 3 rush-hour traffic jams).</comment></comment></comment>


The 6502 microprocessor is 35 years old as of September 16th - <AUTHOR> http://leoville.com/6502-turns-35

<comment><USER2> Ah, memories, memories.

The BBC micro model B was the first ever computer I programmed, at the tender age of 8 or 9. My dad was (still is, in fact) working in the computing department at a university all those years ago and managed to get us all kinds of nice little extras.

Like duel floppy drives - no tapes for me! And I didn't even realise how lucky I was until I visited a friend and we spend 20 minutes loading a game from tape. And visited another friend who saved some of his work to tape, only for the tape to get corrupted somehow, so it never loaded again.

Like sideways RAM. I always thought it was called this because it plugged sideways into the motherboard, but apparent this is not so: <http://en.wikipedia.org/wiki/Sideways_address_space>. This supported an extra 16kB (I think) of memory, and allowed us to run a complete word processor, and my dad used a Pascal compiler - which took up to half an hour to compile his code! I remember him setting it going over dinner... But it used to die on the first compile error found, which did tend to slow things down even more. And we had a daisy-wheel printer, which gave fantastic quality so long as you only required one font at a single size.

Then, a couple of years later, we got a 6502 co-processor connected via the 'tube' (<http://en.wikipedia.org/wiki/Tube_%28BBC_Micro%29>) - an expansion port on the BBC micro. This more than doubled the memory, and ran faster. But various optimizations didn't work. You could no longer write directly to screen address-space, as this was still in the hosts address-space, whereas user programs now executed in the co-processors address space. But, excitingly, there were API calls that allowed you to read/write to/from memory in the host system, so I wrote a (very simple) windowing system that stored the graphics contents beneath each window in the host memory, while executing on the co-processor.

The most ambitious programme I ever wrote was a sideways scrolling shooter game, which was written almost entirely in assembly, and could have up to 50 moving sprites on the screen at the same time without dropping frame-rate. Sadly I never fully completed it, as my dad had just got his first PC at the time and I moved over fairly quickly.

And of course, no discussion of the BBC is complete without mentioning Elite, which was a truely awesome game. They completely re-implemented line drawing routines, as the inbuilt ones weren't fast enough. And they used two screen modes _at the same time_ to allow high definition at the top of the screen, but only in black and white; and lower definition, but in colour, at the bottom of the screen. Try doing _that_ on a PC!

Sigh... Wonderful times... And all in less than 32kB of memory...

<comment><USER3> I have a copy of _Beyond BASIC_ , the BBC Micro 6502 manual, here on my desk!

The Tube version of Elite was amazing.

<comment><USER4> The book that really rocked my world was 'advanced programming techniques for the BBC micro' by McGregor and Watt, I still have it somewhere. 3D graphics, animations sorting & searching, all the good stuff, and explained in a way that made sense to me.

<comment><USER3> That rings a bell - I may even have a copy of it at home!

</comment></comment></comment></comment><comment><USER5> Don't forget what the 6502 was in. The NES used it, the Apple II used it, and the C64, and a few early arcade games, and the early Ataris. The SNES used the 16 bit variant of it called the 65C816, as did the Apple IIGS.

Interesting side note: The Apple IIGS could run normal Apple II 8bit software and GS-only 16bit software... Nintendo had planned the same for the SNES, but bailed on the idea early on, afraid of the backwards compatibility cannibalizing SNES game sales.

Sony, who was an important part of designing the SNES, produced the SPC700 sound DSP (which had a 6502-like instruction set, its own RAM, and a normal DSP companion core to do mixing, panning, volume, and filtering).

Incidentally, Sony had a working prototype for a add-on CD drive for the SNES (it used the expansion port on the bottom most people didn't know existed, and the SNES would sit on the drive). The drive also included a secondary independent 65C816, sorta like SA-1 chip used in Super Mario RPG (which ran 3x faster, had its own RAM, could MMIO and DMA to hardware in the SNES and interrupt the main CPU to do so).

By the time Sony was ready to ship the device with Nintendo, the SegaCD add-on for the Genesis had already crashed and burned, and Nintendo decided to back out because they thought CDs had no future for gaming.

Sony decided to make their own console, replacing the Super Nintendo "component" of their CD add-on, and produced the Playstation. The Playstation sound chip was similar to the SPC700 (but vastly enhanced for CD quality audio), but the rest of the Playstation was decidedly not like a SNES.

Sony, during the development of the Playstation 2, decided to add backwards compatibility as a feature when Nintendo didn't.

</comment><comment><USER6> My first language that wasn't. I taught myself 6502 asm before I have even seen it run. The local British Council library (UK sponsored library going back to colonial times) had 3-5 books on computer programming, all of which I memorized. Among those books was one on the BBC Micro assembly programming.

It had a few worked examples. I used to cover the examples with a sheet, read the problem, then try to solve them before looking at the answer (since I didn't have a physical machine to test things.) -- I quickly came to appreciate that there was no canonical single "answer" in algorithms, and the only way to compare the "equality" of two solutions is see they leave the machine in the same state, given identical initial configurations .. very disturbing thoughts for a self-taught newbie programmer.

I did that for a few weeks and was bored. Then got Robert Lafore's book "Assembly Language Programming for the IBM PC and XT", and I _killed_ it. Hard to explain this, but my first working assembly programs were quite advanced, because I have been "paper hacking" for quite some time by then. I wrote my first apps off of a floppy disk that I used to insert into internet cafe or library computers, when no one was looking (I didn't do any of the PC speaker tricks until much later, when I got my own computer.)

<comment><USER7> So you taught yourself 6502 assembly language while there were already internet cafes? When was that?

<comment><USER6> 1996

</comment></comment></comment><comment><AUTHOR> After all these years the 6502 (in his reincarnations) it's still alive, selling million of pieces (but at 200MHz). <http://www.westerndesigncenter.com/wdc/index.cfm>

<comment><USER8> Wow! Just imagine a 200 MHz Apple II!

</comment></comment><comment><USER9> In 1979, at age 16, I saved money from my paper route and purchased my first computer, an Ohio Scientific (OSI) C2-4P, from Allied Electronics in West Allis, Wisconsin. It had a 6502 microprocessor and 4K(!) of RAM. I used a cassette tape recorder for mass storage (transfer rate was 300 baud), and an RF converter and a television set as my video monitor. This provided a stunning monochrome 80×40 character display!

Within a few months I grew tired of the 15+ minutes it took to load BASIC into RAM from cassette and decided to learn assembly language. This was better since there was a "monitor" program in ROM and therefore always available immediately.

Today, I flip-flop back and forth between thinking, "Those were the days!" and "How could 30 years have gone by so quickly?"

<comment><USER10> Wait, you had 80 columns through an RF modulator on a TV? Wow. I thought it would be pretty fuzzy at 40 columns.

<comment><USER9> My memory is probably failing me. Gads.

</comment></comment></comment><comment><USER11> As it does for many others, news of this chip brings back fond memories.

I was hired for my first programming job at the age of 19 and was tasked with writing a macro assembler for the 6502 from scratch. My manager/mentor had already designed the basics, and handed me a big pile of notes and flowcharts on my first day or work.

Before diving in I wrote a FORTRAN version of the hashing algorithm that we planned to use, and found that we could improve performance considerably with a slight change (I got a raise for doing this).

I wrote the assembler in 6502 assembler, using an existing non-macro assembler that ran on our Ohio Scientific machine. I got it to the self-hosting point as quickly as possible so that I could use the advanced features that I had built into my version. We wrote a set of "default" macros to make the instruction set more regular, filling in some holes.

After some fine-tuning, I was able to compile macro-dense code at several thousand lines per minute. This was on a machine with two floppy disks and 48KB of RAM.

This was an incredible "first project," given that all of my 6502 programs before starting the job had run on my Apple ][ and would fit on a printed page.

I still have the listings for the assembler, and pull them out from time to time to reminisce.

</comment><comment><AUTHOR> BTW: Commondore keeps a page on the history of MOS and the 6502 with a lot of insights: [http://www.commodore.ca/history/company/mos/mos_technology.h...](http://www.commodore.ca/history/company/mos/mos_technology.htm)

</comment><comment><USER8> A couple weeks back I was catching up with the Retrobits podcast and listened to this interview with Chuck Peddle:

<http://retrobits.libsyn.com/index.php?post_id=505602>

<http://retrobits.libsyn.com/index.php?post_id=514107>

<http://retrobits.libsyn.com/index.php?post_id=517736>

<http://retrobits.libsyn.com/index.php?post_id=521785>

Simply amazing.

<comment><USER12> Awesome - thank you for sharing. Excellent interview. Chuck Peddle was the guy who made / marketed the 6502. Lots of history here including mentions of the C64, Apple I, Steve Jobs, Bill Gates, Basic, TI.

</comment></comment><comment><USER13> Ah memories :)

Well, actually more like a lot of moving things around in memory...

MOVEDOWN LDY #0

             LDX SIZEH

             BEQ MD2

MD1 LDA (FROM),Y

             STA (TO),Y

             INY

             BNE MD1

             INC FROM+1

             INC TO+1

             DEX

             BNE MD1

MD2 LDX SIZEL

             BEQ MD4

MD3 LDA (FROM),Y

             STA (TO),Y

             INY

             DEX

             BNE MD3

MD4 RTS

</comment><comment><USER14> I first* learned programming on a 6502-based machine with 1K of RAM and no assembler or basic (Microtan 65, in case anyone remembers that.)

Luckily the 6502's instruction set is pretty easy to memorize, used to know it back to front. Only 56 base instructions and once you understand the way the addressing modes affect the opcode for LDA it's easy to work it out for the others.

Glad I don't have to do that anymore, but it was a great grounding for all the high-level stuff that came later.

(*Well, unless you count my dad's 31-step programmable TI calculator.)

<comment><USER15> Just to be explicit: you mean you programmed it purely with opcodes, presumably compiling by hand a program you'd figured out earlier?

<comment><USER14> Yes, I programmed it purely with opcodes. The machine was just running a very basic "monitor" that let you write instructions and data into memory in hex and then let you run them.

At first the machine did not even have a cassette interface, so there was no way to save programs and you had to type them in every time. The machine came with some examples, like Conway's "Life". Given that the machine really only had about 256 bytes of usable program storage (half the 1k was used for video) this wasn't quite as bad as it sounds but still pretty tedious.

Actually when I first got a cassette interface I still had to type the cassette loader in by hand to boot :( Eventually I got the rom expansion that included the cassette loader and an assembler.

Obviously writing a program directly into memory in opcodes does involve some upfront thinking, but you'd be surprised how "REPL-like" the coding experience could be :)

</comment></comment></comment><comment><USER16> I was surprisingly impressed by meeting Brad Templeton in Silicon Valley in ~2006, not because he was a board member at the EFF, nor that he founded Clarinet, but because he wrote PAL, an assembler for the C64 that I used back in the day.

</comment><comment><USER17> After all these years, I think the 6502 instruction set is still the one I know best.

<comment><USER4> I only remember 0x00 and 0xEA these days :)

All the rest of them have slid in to the swamp of time. The 6502 was a funny chip with it's zero page access and lack of a 'mul', to some extent not having a mul makes you a better programmer (you'll have to roll your own, and that will lead you to discover look up tables for nibble sized chunks pretty quickly because of a perceived lack of performance), and the 'zero page' was a good preparation for knowing how to deal with memory with different degrees of accessibility (think of caching and demand paging).

I worked a lot with the 6809 as well, and that was a much richer instruction set (and more orthogonal too), but I did not learn as much from that as I did from the 6502 because of the more restricted environment on the 6502.

I believe my first 6502 based computer had all of 1K of RAM :)

Single board job with a hex calculator keypad and 6 7 segment displays and an fsk based tape interface.

<comment><USER18> Did any peer chip have a mul in the late 70s/early 80s?

<comment><USER4> 6809 did 8x8 mul.

<comment><AUTHOR> 6809 was one of the first to have a mul instruction, and was used in the initial development of the macintosh: <http://www.folklore.org/StoryView.py?story=Good_Earth.txt>

</comment></comment></comment></comment></comment><comment><USER19> Maybe this is a good time to toss up the half-finished 6502 simulator I have kicking around.

</comment><comment><USER20> My first assembly language. Ahh, the beauty of limitation

</comment><comment><USER21> Related: <http://www.visual6502.org/JSSim/index.html>

A 6502 emulator in JavaScript, visualizing the actual core and its electric flow during operation, cycle by cycle, instruction by instruction. If this is not Hacker News worthy, I don't know what is.

<comment><USER22> Wow - that was made by extracting the gates & nets from de-packaged die photographs! It is actually a transistor & wiring simulator (in javascript) that has a 6502 description loaded (and a simulated memory device tied to the pads)</comment></comment>


Google+ traffic grew by 480% in one month so press reports a 60% decline. - <AUTHOR> https://plus.google.com/u/0/113117251731252114390/posts/AZh8wwb76vR

<comment><USER2> The source is the Daily Mail. Anyone familiar with that rag will know never to take whatever they say as truth.

Surprised they didn't run with 'Google+ gives you cancer'.

<comment><USER3> Funny. True in general. But in this case The Daily Mail aren't necessarily being deliberately disingenuous.*

What the original post is saying as that when the doors opened to the public, Google+ traffic went up nearly 5-fold in a month from a private Google-staff- and-their-freinds beta.

Even if we ignore the fact that it went up 1200% and then dropped back again, 5-fold seems a little disappointing.

Also, surely it is correct reporting to point out that there was a massive drop-off effect. People signed up in their droves, tried it and then left.

No matter how Google try to spin this, it can't be good. If Google+ continues to slowly build back over the next few months then maybe they will be fine. But, based on a small biased sample of my 'social graph' it doesn't look like it.

*—I can't believe I'm defending The Daily Mail.

<comment><USER4> Whatever happens with G+, I hope it stays around. It's twitter with longer posts, and facebook without the idiots. Aside from the network effect not having kicked in yet, it really is an ideal service for me.

<comment><USER5> We had a service like that in Finland, called Qaiku. Now quite a lot of the users seem to have migrated to Google+

</comment></comment></comment></comment><comment><USER6> [http://insights.chitika.com/2011/failure-to-launch-google- gr...](http://insights.chitika.com/2011/failure-to-launch-google-growth-spurt- short-lived/) is the source article.

the 1200% number came from "Reportedly, Google+ saw a surge in traffic of over 1200% due to the additional publicity, but the increased user base was only temporary, as was projected in an earlier insights post." and the 60% drop came from "But, soon after, traffic fell by over 60% as it returned to its normal, underwhelming state."

but the graph right below that shows Google+ going back (in Chitika's "traffic index", whatever that is) to just about where it was before it was made public. as a result, I don't think those two numbers can be composed, and the "heh, guess 480% doesn't count for anything" smugness I've seen from a couple different places is based on everyone else's misconception of what the numbers mean.

<comment><AUTHOR> The data in question is suspect as no hard data is shown nor are they saying on how many users the report is based on or how they were able to measure traffic at all. Chitikta is a Google competitor of sorts their business is ads and they do have a strong partnerships with Facebook.

<comment><USER6> this link is some tech blogger's recapitulation of a Forbes tech blogger's expose of a Daily Mail article announcing Chitika's press release.

how is it any more trustworthy? at least Chitika's page has a graph on it (though they're tight-lipped about what that graph represents.)

<comment><USER7> As a Forbes employee, it bothers me that it appears that Forbes is the source of the misleading statistic rather than the outlet that published the analysis of its incoherence.

We have a lot of really smart non-staff contributors (like Tim here, or my personal favorite Timothy Lee) and they never get enough credit for the independent thinking and analysis

<comment><USER8> Tim's analysis in Forbes _is_ the source of the misleading "480%" statistic -- and the Forbes headline trumpeted the equally-misleading 60% statistic. So, while I think that Forbes' blogs are frequently quite insightful, this wasn't one of your better moments.

</comment></comment></comment></comment></comment><comment><USER9> > On the day they opened the floodgates to the public, traffic immediately > spiked by 1,200%. These new people were mostly enthusiastic new users. But a > minority was tire-kickers who didn't stick around.

> When the dust cleared, total traffic was nearly five times higher than > before the doors opened.

A 1200% to <500% drop is categorized as a "minority" of users leaving?

</comment><comment><USER10> Tried to close my Google+ account and the choices it presents were confusing at best ( this will delete your Google+ and also/maybe your Gmail? )

So instead chose a fake last name and got banned. MISSION ACCOMPLISHED :)

<comment><USER11> You got banned after changing your last name? Are those bans done by hand?

I know, that they have a real name policy but so has Facebook. A lot of my friends and family changed there real names into fake names on Fb. Nobody got ever baned.

<comment><USER12> I had my name changing rights taken away on Facebook. I got a message saying I had breached the rules to many times and my punishment was keeping the last name I entered LOL

I used that fake name for 2-3 years and only decided to try changing back recently and it worked. I wonder if it was a bluff by Facebook and I could have changed again at any time however.

</comment></comment></comment><comment><USER13> I assume there will be much tighter integration of Google+ into the next major release of Android which should help solve the 'ghost town' problem so many people are seeing with Google+ at this point. Ultimately they may have to give SmartPhone makers some incentive to stop bundling the Facebook app/integration on their devices. (or just make their own)

<comment><USER14> > Ultimately they may have to give SmartPhone makers some incentive to stop > bundling the Facebook app/integration on their devices.

Read: <http://en.wikipedia.org/wiki/United_States_v._Microsoft>

I'm not trying to be snide either, Microsoft leveraged its relationships with OEMs to incentivize them to stop bundling netscape. I don't think that Google would play that dirty, but it's certainly thin ice.

<comment><USER15> Google isn't a monopoly.

<comment><USER16> But they probably have the size and the market power that would make regulators take an interest in such behavior.

</comment></comment></comment></comment><comment><USER17> their double standard on real/fake names is a disgrace.

they ban people for using their internet handle that they have been using for the last 15 years and on the other hand celebrities like madonna or 50 cent are allowed to use their artist names

<comment><USER18> This is, indeed, terrible. I guess we should all make music.

</comment></comment><comment><USER19> The Daily Mail (and Sunday Mail) is a right-wing, racist, anti-science paper which goes out of its way to seek out inflammatory and exaggerated headlines to scare the public and sell more papers. I wouldn't give them the time of day.

<comment><USER20> I have to respect the balls with which they present utter nonsense, and the purity and refinement of their art of utter nonsense.

</comment></comment><comment><USER21> Google:Social::Microsoft:Search

</comment><comment><USER22> Ok, instead of reading the daily mail or various G+ posts, I went to the source: Chitika.

They show a clear spike and return back to normal levels, as can be seen in the graph on this page: [http://insights.chitika.com/2011/failure-to-launch- google-gr...](http://insights.chitika.com/2011/failure-to-launch-google- growth-spurt-short-lived/)

Key Notes:

1\. Chitika's conclusions from the data are sketchy and I don't put much stock in them.

2\. The overall spike and rapid decline back is undeniable and troubling.

3\. The press of course likes headlines and Google is most certainly not a media darling any longer, thus the news sensationalizing a relatively humdrum statistic.

~~ Chitika's headline is quite clearly accurate ~~

<comment><USER23> Key Note: The Chikita graph measures a 'traffic index', which could be anything.

The bump is because G+ launched last week and it was linked to from Google.com - the most popular web page in the world

Show me a product that has launched and not experienced a traffic 'bump'

If you measure the backend of that bump, you will always show a decline. Zoom out.

And that is not to mention that Chitika do not publish their traffic collection methodology. It is just some chart they pushed out to bloggers in a press release (with their branding on it!) and all these bloggers have been far too quick to publish.

edit: this tilted me enough that I wrote a blog post about it : [http://nikcub.appspot.com/lies-damn-lies-and-google- statisti...](http://nikcub.appspot.com/lies-damn-lies-and-google-statistics)

</comment></comment><comment><USER24> Being the size Google is, I sometimes wonder why it took them so long to come up with an alternative to Facebook. If they had of launched Google+ back in 2005 or 2006 I think they would have had a decent chance against Facebook but launching in 2011 was just a bad business move.

<comment><USER25> No, you ignored that social network was not what it is today. And Facebook played an important role in shaping what the social network should look like. Google had its social networking site at that time, but they failed to iterate on it. Facebook's success is not accidental, there were a lot effort and thinking into it to make what it is today, and people shouldn't take it for granted to say that they can come up with a Facebook alternative in 3 months at 2005.

</comment></comment><comment><USER26> I feel like G+ is like a breath of fresh air after having 50 or more mundane minutia thrown at me every few minutes on Facebook. It's exhausting, especially that new ticker.

G+ is clean, wide open and just the content people want to share at that moment. Not also what page they liked 3 months ago, the last 4 spotify songs they listened to and all the comments they made on other people's posts they made (that are often not even people on my friend's list. Hello privacy?!?)

<comment><USER6> how do you know that this isn't due to the (small, even if we're being charitable) size of the community rather than a G+ design choice? if it's the former rather than the latter, your days of liking G+ are numbered.

</comment></comment><comment><USER27> well the argument of number is tricky since nobody has the number except Google. But another product of google's own, Google Trends, do help to see the decline. See here:

<http://bit.ly/rlq9aR>

<comment><USER23> that is people searching for 'google+'

a more accurate graph is:

[http://www.google.com/trends?q=plus.google.com&ctab=0...](http://www.google.com/trends?q=plus.google.com&ctab=0&geo=all&date=2011&sort=0)

and that only shows up until the end of Sep and doesn't include the few days last week that google+ was linked to from the homepage of google.com

<comment><USER28> They are a bit less than allrecipes.com

[http://www.google.com/trends?q=plus.google.com%2Callrecipes....](http://www.google.com/trends?q=plus.google.com%2Callrecipes.com&ctab=0&geo=all&date=2011&sort=1)

7M uniques: <http://www.quantcast.com/allrecipes.com>

I would estimate G+ getting 5M uniques. However, what would be interesting is to know the pageviews.

Facebook recently said they had recieved 500M visitors in a single day.

<comment><USER23> I don't think pageviews per visit is anywhere near what it is in Facebook - probably even by an order of magnitude. That is just my own perception from using it, though.

Facebook really do know how to suck time out of their users.

</comment></comment></comment></comment><comment><USER29> Vanity metrics much? A huge part of the reason why Google+ will fail is Google's encouraging spread of vanity metrics instead of just admitting that Google+ has a _serious_ , _serious_ challenge and is still on course to die(it's already pretty irrelevant in the made-up social networking wars).

Heck I'd venture to say that myspace.com has more engagement than Google+. And that is after Google shoving G+ onto its users.</comment>


A website dedicated to reviewing and comparing smart bulbs - <AUTHOR> http://smartbulbreviews.com/

<comment><USER2> why? except energy why there is so much craze about smart bulbs?

<comment><AUTHOR> Well, there are a lot of applications that can be done with them through the integration with IFTTT and through their API. As an example I am using it as a wake up alarm and it surprisingly works. I wrote about my experience with it here [https://medium.com/the-internet-of- things/b8b2d741910a](https://medium.com/the-internet-of-things/b8b2d741910a). I also made it turn green through ifttt when the TSLA stock which I am investing in rise up by 3%. At big web services companies as Microsoft, they also use them as a visual fast way to monitor the health of the web service. The possibilities are just endless on what you can do with them.</comment></comment>


Is Udacity Worth It? - <AUTHOR> Since Udacity is giving one month free access on all its nanodegrees, Iam planning to enroll. Any suggestions? <comment><USER2> I tried some small classed on Udacity a while ago but there where a lot of bugs and the course work was too easy. This was before Nanodegrees became a thing but untill now i have only done different courses on EDX, 9 in total from MITx, ColumbiaX and UCSanDiegoX because I thing there courses from good universities are of a better quality.

</comment><comment><AUTHOR> I read a review about Udacity. [https://onlinecourseing.com/udacity- review/](https://onlinecourseing.com/udacity-review/). Now Iam thinking of giving it a try</comment>


BitTorrent News to Launch at Republican National Convention - <AUTHOR> http://blog.bittorrent.com/2016/07/13/bittorrent-news-to-launch-at-republican-national-convention/ <comment><USER2> I think it would be really cool to have some type of audience participation built into a system like this. One of the parts that I hate most about watching the news is that I know I'm watching a singular viewpoint, and that nobody else has a chance to provide commentary on the topic at hand. Considering how much BitTorrent stressed that they wanted to provide a independent coverage, I think that some type of viewer input would be fantastic. It would help take watching the news into the interactive age.

<comment><USER3> Every example of a call in style audience interaction I've seen winds up being dominated by 'pranks' or off topic ramblings.

</comment></comment><comment><USER4> I'm not sure what their (BitTorrent TM) business plan is. First of all you have the problem of the name. The BitTorrent name is tainted with illegal sharing activities, and has been so for the past decade. Then there's the problem of monetizing something like this where you have other platforms like YouTube that work quite well for streaming live video, and they're pretty much free.

Also, can't download neither BitTorrent Live and News, and there's no source code. How do these people make money and/or stay relevant?

I'm not claiming p2p live video streaming is an easy task, and in fact, it seems to be an impossible task at this point, otherwise we'd see open source projects that make p2p video streaming work, and we don't.

It seems to be more of a bandwidth problem, rather than a software/algorithm problem: if the video isn't extremely relevant (lots of peers sharing it) and/or the source peer doesn't have lots of bandwidth, then this will simply not work.

<comment><USER5> "Our main source of revenue is off the toolbars we push out, which isn't a great source of monetization, but it's something. You can do the math on how many installs we have and what the monetization of toolbars is, and subtract out the costs of having 50 employees, and you'll get a reasonable ballpark of how profitable we are, although the short answer is very. Even lousy monetization works well when you have more users than Twitter." \- Bram Cohen

[0] - [https://www.quora.com/How-profitable-is-BitTorrent- Inc](https://www.quora.com/How-profitable-is-BitTorrent-Inc)

</comment></comment><comment><USER6> Might be interesting if they actually open-sourced the underlying Bittorrent Live protocol, which they have explicitly stated they won't do Because Piracy.

</comment><comment><USER7> Surprised that they choose apple as the first ecosystem to launch in.

</comment><comment><USER8> Yeah, because I'm totally going to be interested in listening to a bunch of Al Jazeera reporters try to do Al Jazeera America again. Totally unbiased reporting, that. :P

<comment><USER9> Al Jazeera America wasn't bad, and probably more even handed than most US news sources... in-line with BBC America imho.

That said, most people prefer their news source biased to their own political leanings.</comment></comment>


So, you want to build a CubeSat? - <AUTHOR> https://orbitalindex.com/archive/2019-07-30-Issue-23/ <comment><USER2> If you are interested in open-source licenced Cubesat hardware, software and low earth orbit communications feel free to check out Libre Space Foundation

[https://libre.space](https://libre.space)

Feel also free to check our repositories at Gitlab. [https://gitlab.com/librespacefoundation](https://gitlab.com/librespacefoundation)

<comment><USER3> LSF FTW! :)

Great to see the SatNOGS network going from strength to strength!

<comment><USER2> We couldn't do it without our awesome community

</comment></comment></comment><comment><USER4> I highly recommend subscribing to The Orbital Index newsletter. One of the 3 newsletters that I actually read every week. It's (almost) completely outside my profession but very interesting to read nonetheless.

<comment><USER5> what are the other 2?

<comment><USER6> Not op, but The Prepared is great if you have any interest in manufacturing, supply chains, and modern infrastructure.

[https://theprepared.org/](https://theprepared.org/)

<comment><USER7> One half of Orbital Index here… I highly recommend The Prepared as well. I happen to be guest editing it next month while the normal writer is on paternity leave, so I might be biased (but also a longtime happy reader :-).

</comment></comment></comment></comment><comment><USER3> @tectonic: thanks for including mention of our website/resources in this newsletter! Looking forward to meeting next week at SmallSat :)

If you're interested in understanding the state of the global space supply chain, check us out [1]. We're working on digitalizing the entire global marketplace and CubeSats are a huge part of the on-going commoditization within the sector. Kinda like "Octopart for space".

The supplier ecosystem is really a lot larger than people think (including myself until we started this project). There are some legacy and strategic reasons for "hidden hubs".

The supply chain is undergoing a lot of change, as organizations try to figure out how to not stay hidden and instead ride the on-going growth wave through international business/projects.

[1] [https://satsearch.co](https://satsearch.co)

</comment><comment><USER8> How effective is an internet connection from a CubeSat?

I'm curious, I've read about radio comm and this article mentions using the GlobalSat or Iridium network is possible, but would that (or any other option) be a "broadband bandwith" available to whatever software is running on the CubeSat?

<comment><AUTHOR> For the radio & antenna you'll probably have on a small CubeSat, expect slow and unreliable, but it depends on if you're running your own ground station, in which case you may only be able to communicate for minutes a day or less, or are using a large ground station network or satellite constellation like Iridium, which will still be slow, but will offer much more frequent communication opportunities.

<comment><USER9> Here is a slow scan TV signal I picked up from the ISS one day when I was farting around with nothing better else to do.

[https://streamable.com/q9oa0](https://streamable.com/q9oa0)

<comment><USER10> That is so cool!

</comment></comment></comment></comment><comment><USER11> Now I want to build a CubeSat that will point a laser pointer at different population centers as it passes around the earth. E.g. this pass of North America you choose LA, then NYC, then Houston, then Chicago... so you can see it streak by in the sky.

My rough estimation is you could create a spot 2 miles across with a standard laser pointer at 400 miles high. Maybe you could use a different kind that would have a little more spread. And you'd have even more if you weren't beaming directly downwards -- maybe you could point it at 45 degrees or more with a powerful laser and get nice coverage.

<comment><USER5> For a while I thought you would need too much energy, then I realized I don't know well enough the physics of how a laser works.

[Warning, very stupid idea ahead]: Since I don't know well enough the topic, why wouldn't be possible to use a satellite to collect solar energy (because outside the atmosphere you can collect ~40% more (edited) the solar energy due to lack of atmospheric filtering effect),and then transmit that energy back to earth via some sort of wireless energy distribution mechanism (laser?). I guess a YoYo satellite with real tens of KM of wire to earth has a lot of reasons for not be feasible.

<comment><USER12> It's not 40x more, it's barely 40% more. [1]

> Average annual solar radiation arriving at the top of the Earth's atmosphere > is roughly 1361 W/m^2. The Sun's rays are attenuated as they pass through > the atmosphere, leaving maximum normal surface irradiance at approximately > 1000 W /m^2 at sea level on a clear day.

There are practical challenges, but otherwise, yes, it should work.

[1] [https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on...](https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on_Earth's_surface)

<comment><USER5> Thank you for the pointer! I've updated the original comment, and my knowledge base too :)

</comment></comment></comment></comment><comment><USER13> This is an awesome post and I love the external links given. I've been reading a lot of satellite engineering books and resources lately but they're unfortunately mainly geared for much larger missions. This article, and really most cubeSat info, is really useful for the amatures like myself.

</comment><comment><USER14> I am almost finished working my way through the book "Building High Integrity Applications with SPARK"[1].

I dropped Rust and found SPARK easier to work with, and one of the book's authors is a professor at Vermont Technical College (VTC) in the CubeSat Laboratory[2] where Ada/SPARK are used.

The book is a great way to get exposed to a lot of subjects around high integrity, secure software. Highly recommended.

[1] [https://www.cambridge.org/core/books/building-high- integrity...](https://www.cambridge.org/core/books/building-high-integrity- applications-with-spark/F213D9867D2E271F5FF3EDA765D48E95)

[2] [http://cubesatlab.org/](http://cubesatlab.org/)

</comment><comment><USER15> What are some ways that an individual person could benefit from their own CubeSat?

<comment> Jim- For the average person, probably not much; The main blocker will be that it costs about $10k to build, $20k to have it launched into space (USD).

<comment><USER16> Adjusted for inflation that is not too much different from buying a couple of Apple Macintosh computers in 1984.

<comment><USER17> Honestly, I might start saving for a few years and actually do it. It sounds like a thing that would be awesome to do and more so, a good experience in general.

Would there be any restrictions for people not living in the USA?

<comment><USER18> To my knowledge, you have to check with the space agency of your country, they probably know more too.

</comment></comment></comment></comment></comment><comment><USER18> The interesting challenge would be when the first cubesats launched by private persons reach the moon and send back a picture of earth rise.

From what I can tell, cubesats might be able to get ride-alongs on future launches towards the moon, so that is basically what this challenge would be hinging on.

You'd have to figure out long distance communication, a simple LoRa module won't cut it. Your power needs to handle 3 days of travel, possibly without power until the sat gets deployed and sees the sun for the first time.

You'd have to figure out how to orient and point a camera outside the stronger parts of the earth's magnetic field (commonly cubesats seem to rely on magnets to orient themselves).

Then you'd have to bring a camera with decent quality and that works in vacuum along, snap a picture or ten and finally send them back.

It would be awesome if I, as a private person, could organize and launch that.

</comment><comment><USER19> I had this thought, why not build a small rifled tube with an explosive charge and bullet like projectile.

The projectile has a rocket motor too.

Get the cannon as high as possible with a balloon.

At the limit, the cannon fires the projectile at high velocity. The rocket motor ignites giving the extra velocity.

Do you think it could reach escape velocity?

IANARS (I am not a rocket scientist)

<comment><USER20> The last guy that tried this was murdered by Sadaam.

Most people underestimate the speed required to obtain a reasonable orbit, and the amount of tube required to accelerate an object to that speed.

<comment><USER21> He worked for Saddam, he was murdered by Israel or possibly Iran.

<comment><USER20> interesting. For what I remember of reading this story many years ago is that he got on the badside of Saddam for not delivering what he promised to deliver. I'll have to reread the story.

</comment></comment></comment></comment><comment><USER22> Why build it if the cost is 10K+ to deploy?

<comment><AUTHOR> ...it's really not that expensive anymore. [https://space.stackexchange.com/questions/20009/cubesat- laun...](https://space.stackexchange.com/questions/20009/cubesat-launch-costs)

<comment><USER23> According to your link the price is more like $100k+

<comment><AUTHOR> The point is that a launch cost of $100k is totally manageable by a startup, which is very different than a decade ago.

<comment><USER24> The point is that $100k > $10k, so stating that "it's really not that expensive anymore" is false.

</comment></comment></comment></comment></comment><comment><USER25> > So, you want to build a CubeSat?

Not particularly, and even less so with this clichéd, condescending headline.

It's a meme that needs to die, why do we have to see these titles popping up in HN every month?

<comment><USER26> After reading your comment, I understand why people stereotype HN comments as being negative, whiney and neurotic for no reason at all.</comment></comment>


New Edition of Practical Artificial Intelligence Programming with Java - <AUTHOR> https://leanpub.com/javaai <comment><AUTHOR> I updated my book Practical Artificial Intelligence Programming With Java, a major revision. Free update from earlier editions and free to read online. Creative Commons License.

The 2020 edition is a major rewrite from the 2013 edition with a new deep learning chapter and 2 new Semantic Web chapters. Mostly a new book except for the chapters on Search and Reasoning.

[https://leanpub.com/javaai](https://leanpub.com/javaai)

Note: the code and a PDF for the 2013 edition are available here: [https://github.com/mark-watson/Java-AI-Book- Code_4th_edition](https://github.com/mark-watson/Java-AI-Book- Code_4th_edition)</comment>


React: We're After You ◕ ◡ ◕ - <AUTHOR> http://gluecodes-demo.s3-website.eu-west-2.amazonaws.com/ide-structure.html?appId=1&edit=page&id=index <comment><USER2> Please don't do baity things in titles. Make the title factual and neutral and tell people what it is that they're looking at. It can be good to add a first comment to the thread, also factual and neutral, to give additional context.

Edit: it looks like we've had to ask you this before: [https://news.ycombinator.com/item?id=23263421](https://news.ycombinator.com/item?id=23263421). Did you not see that one?</comment>


'Verified by Visa' Forces Users to Select Weak Passwords - <AUTHOR> http://blog.zorinaq.com/?e=54

<comment><USER2> Unless I'm missing some technical trick, passwords are actually stored in plain text, not hashed at all. My reason for this assumption is that in some cases (I think it depends on card provider), instead of typing in the password, you just type in 3 specified characters from it (e.g. "please enter the 3rd, 5th and 6th characters"), certainly this is the case for my Visa debit cards from Barclays.

Is there any way they could verify a single character against a hash, or am I right in thinking it has to be stored plain text?

So many websites have annoyingly dumb password rules, just yesterday I was told that my "use this on a bunch of sites I don't really care about" password (which is long and contains upper/lower/numeric/special characters) couldn't be used because it had "recurring letters", i.e. the same letter was next to itself in one occasion. Therefore my password for that site is now "fuckingcunts", in my childish hope that some day that company will ask for my password over the phone.

<comment><USER3> If it were possible to verify a single character in a hash, then you could attack a hash by verifying the first character, then the second character, etc, until it results in the hash.

So nope. Not possible.

<comment><USER2> Well for example, the suggestion from colinhowe.

</comment></comment></comment><comment><USER4> I always get double freaked out when I see requirements like that, because I assume that the "special characters" restriction is required for some homebrewed crap rot13-style idea they have for obfuscating the passwords instead of hashing them. I literally can't imagine how such a restriction would arise unless they have a bigger problem.

<comment><USER5> I always assume there's old mainframe code involved whenever I see a requirement that says "less than 8"

Especially in the financial sector.

Mainframes are weird. They are still used in a lot of places and don't play by sensible rules. People still run these systems with 24x7 operations staff, as in, there is someone sitting in front of the mainframe console at all times.

It is a crazy world out there and a lot of people still use these systems to do terrifyingly important things.

<comment><USER6> Mainframes are still in use partly because (until perhaps very recently), they are bar-none when it comes to high-availability and disaster recovery.

I did some work in COBOL on a Unisys mainframe back in the late 90s, and I'm still impressed by that thing. You could walk over, pull the plug on it while it was in the middle of running a payroll job, a finance job, and half a dozen other things. Plug it back in, wait a few minutes, and it would pick up right where it left off. No data corruption, no other hassles.

Migrating away from that thing was often discussed, but it would have been a tremendous hassle. For one, there was no simple way to migrate the huge volumes of data off of it; for another, even if you could, decoding it would have been a neat challenge. Then there was the matter of all the years of business logic that, while not pretty, worked with very few problems.

...and this was just for a school district in the East Bay. I can't imagine what it would look like for a big financial company.

<comment><USER5> Mainframes are very much impressive, I've worked with one before. They just operate very very differently from an "open computing" environment that we're all used to.

Once you rely on a mainframe the cost of continuing to operate it, while fairly large, is hilariously less expensive than moving all that code and data elsewhere. Especially given you will have to test all the code again and most people don't even know what it all does anymore, much less how to make sure it's doing it correctly.

</comment></comment></comment></comment><comment><USER7> Well, the idea is that your account is irrevocably locked out if you guess the password wrong 3 times. So the size of the keyspace does not really matter. The attack on this system is calling Visa and pretending to be you, not guessing passwords.

Remember: when you are using a credit card, you are spending the bank's money, not your own. So if the bank doesn't want you to use a long password, it's their loss when someone compromises their database. You say "that charge was not authorized" and the bank eats the loss.

This is different than an email or Twitter password, because when someone compromises your email or Twitter account, the damage to your reputation is _your_ problem. But credit cards are different: it's not your stuff at stake, so you shouldn't really care about how they do security. Their goal is to reduce fraud without stopping you from using your card.

<comment><AUTHOR> Online bruteforcing attacks basically don't matter.

I am guessing you did not read the end of my post giving 3 other reasons why the keyspace size does matter (no. 1 being for PCI DSS compliance).

<comment><USER8> Does PCI apply to the credit card associations?

<comment><USER9> That's a really good question... I wonder?

</comment></comment></comment></comment><comment><USER10> My banks password system is terrible. It must be between 6-8 characters long, and no special characters allowed. When I originally created my password, I didn't read the rules and typed one of my "usual" ones in. It consisted of a dictionary word, followed by a series of numbers and special characters.

Because of their inferior UI, I never noticed my password was getting truncated at 8 characters long, which just so happens to be the length of the dictionary word. For almost 4 years my banks password was an eight character dictionary word instead of the 'slightly more secure' 14 character version I thought I was using all along.

</comment><comment><USER11> I'm surprised by the number of financial services I use that have forced me to use a weak password. It's appalling.

</comment><comment><USER12> I very much dislike verified by visa.

I would much rather visa allowed generation of single use CC numbers backed by a user-specified monetary amount, for online shopping. I think discover card used to do this (not sure if they still do). That always seemed like a better idea to me.

</comment><comment> X-Istence Verified by MasterCard or whatever their program is called has the same restriction, and it doesn't make any sense. First time I saw the form I called my bank to verify that I was supposed to be seeing that form and that it was safe to enter my data.

</comment><comment><USER13> American Express does the same thing!! My user name is actually twice as long as my password by virtue of their restriction.... It seems like they're actually hoping for a PR disaster.

</comment><comment><USER14> I have to sign my purchases with a OTP generated by a small card reader and my card (+ PIN for the card)...

</comment><comment><USER15> That's quite odd. My Verified by Visa password is significantly longer than 8 letters.</comment>


The Wake-Up Call - <AUTHOR> http://www.businessinsider.com/the-wake-up-call-2010-12 <comment><USER2> I know far too many families that have broken up because of "Daddy who is boring". When your kid says that you know that your wife has been thinking that for even longer. This isn't just those in the start-up space. Microsoft, in their WP7 "Really" ad/social commentary already summed this up perfectly.

</comment><comment><USER3> It's interesting how kids are so honest about their feelings. He didn't learn this from his wife, and if you think about it it's highly likely it's affecting their relationship as well. People should be more open with their feelings.</comment>


Ask HN: Pricing Models for Subscription Services... Your Experience? - <AUTHOR>

A question for the HN community as it pertains to subscription packages and pricing...
1. As a consumer, are you more included to purchase monthly subscriptions at a slight premium (ie $3.99/mo) or purchase an annual subscription at a slight discount (ie $29.99)?
2. As a company charging subscription rates, do you find that users tend to opt for shorter term billing for cheaper monthly bills or prefer longer term packages for convenience?
3. One of my companies sells a one-time charge of $39.99... very successfully! Do you think it is wiser to charge slimmer annual rates (ie $24.99) and a lifetime charge at say $59.99? Or, for instance, some type of similar package? <comment><USER2> 1\. Monthly - I like the thought I can cancel whenever I want without a big hassle w/ refunds, pro-rating, etc.

2\. Monthly subscriptions are really hitting their popularity peak right now. It seems to be the way to do business now - I've never attempted to offer an annual, not sure how it would perform. I would assume not as well though, knowing my target market.

3\. I would never offer a lifetime package. The state of my application may change drastically where the standard featureset is worth much more than the lifetime user paid. If your application is "stagnant" and kind of operating itself, I don't see the harm though. Might get messy if you change the lower- level subscription prices.

<comment><USER3> In reply to 3.

If your application changes enough, then isn't it a different app, thereby allowing you to charge for a new feature set?

Seems like ideal price discrimination to me (good for producer/provider).

<comment><USER2> Well, think about Backpack. It made the transition from being a personal data manager to being an "Intranet" platform.

If you had charged a lifetime fee to start, and then done all of the work to make it the new Backpack, how do you convince your users that even though it has the same name, and same look, it's worth purchasing another license.

Seems like a premium way to lose users and have the blogosphere come at you Frankenstein style (burning torches and all).

<comment><USER3> Your point is well-taken.

What if I were to instead develop version X of my original product under a new name? I could bucket test the features I want to add, a few at a time. When I am "done" with the new version, I could then release as a new product and invite users to pay an upgrade fee -- with the caveat that the old version will stop receiving support/etc after a given date in the future (or perhaps even charge for support after that date in such a way it makes more economic sense to switch).

I may make an addendum to this post when I am slightly more lucid in the morning.

P.S. Come to think of it, isn't this what MSFT does with the Windows line -- and last I heard, they have been quite successful.

<comment><USER2> Yeah, I guess it really depends on what your product is. I am merely thinking SaaS in my posts, but I could see a lot of other applications (and have purchased some myself) that take a different route.

For instance, ExpressionEngine or the Torque Gaming Engine. When you purchase a license you are only purchasing a license for free updates to that version (let's say the 1.0 branch). When EE 2.0 comes out, you will have to pay an upgrade fee to use the new version (albeit, heavily discounted, compared to purchasing a completely new license).

It all comes down to what your product is, who your target market is, and what the trends within that niche are. Obviously you would take vastly differing approaches between building the next Backpack or selling an Enterprise grade Help Desk system to the Department of Defense. :D

</comment></comment></comment></comment></comment><comment><USER4> It depends on what I'm buying. I like that when I buy Flickr I don't have to think about it every month I can just buy it and know I've made a choice for a whole year and it's done.

But on apps like Basecamp or Freshbooks I like the monthly since it isn't a huge chunk of money up front.

<comment><USER5> Is this just a price thing, then? Or, perhaps, something more?

If Basecamp/Freskbooks were $25/year, would you rather pay for the entire year up front, or would you continue to pay monthly?

If you'd pay for the entire year up front, at what price do you consider it to be too much? Where's the crossover point for you?

</comment></comment><comment><USER6> I tend to buy software and services in that price range by the year for both myself and clients. Expensing or invoicing a small monthly charge is too much hassle. Note, however, I am more hassle sensitive than price sensitive. I am also somewhat resistant to automatic charges, but that is probably just me. OTOH Neflix goes quite well with a small monthly charge. Maybe the yearly charge for them is a barrier.

Your charge is so small that I suspect the recurring charge will generate a lot more money than a one-time charge or the lifetime charge.

<comment><AUTHOR> Terrific line:

Note, however, I am more hassle sensitive than price sensitive.

</comment></comment><comment><USER7> Do you have enough volume to consider A/B testing?

Given a large enough sample size, you should be able to determine an optimum pricing scheme.

I'm no expert on A/B testing, just my $0.02.

</comment><comment><USER8> You should read both of these items that make a case for going with a monthly charge instead of annual.

[http://www.braintreepaymentsolutions.com/blog/annual- credit-...](http://www.braintreepaymentsolutions.com/blog/annual-credit-card- billing-subscriptions/)

[http://www.37signals.com/svn/posts/753-ask-37signals-how- do-...](http://www.37signals.com/svn/posts/753-ask-37signals-how-do-you- process-credit-cards)

</comment><comment><USER9> First of all, you need to figure out whether or not you're building a consumer or business product.

"Would I give this to somebody as a gift?"

If Yes, you have a consumer product. If No, you probably have a business product.

For business products you want to think in terms of expense accounts. You can bet that ~$20-$30 is super easy on up to ~$300-$500. The problem with subscriptions is that it can scare some people off who only need to use the product once.

For consumer products, I have no idea. I just know that consumers are generally more discretionary with how they throw their money around.

Education customers will just give you a lot of buzz but not much money (from my experience).

</comment><comment><USER10> I have found that pricing should be determined according to your audience but should various payment-options should be discussed and developed. Having a broad audience, it would be wise to open with a shorter bill term having a slightly higher rate than that of a longer-term (i.e. monthly vs. annual or annual vs. life-time). With the unsteady economy, each client will have their own perspective as to what may benefit their financial needs/flexibility. As it pertains to a customer preference, remain receptive of your audience.

</comment><comment><USER11> When I was landscaping, I offered a yearly rate which was a 10% discount. 15% of my customers took me up on it which gave me the money I needed my first year to buy equipment plus a little extra capital.

Just be sure to have a cancellation policy in place and cash on hand to not piss off already unhappy users.

</comment><comment><USER12> As for 1, it depends solely on price.

If it's say, like that? I'll probably buy a year. If it's more like $9.99 or more a month, then, I'll probably do it monthly to avoid that single large expenditure.</comment>


Technologically Clueless Grandstanding Senator Calls For US To Ban Bitcoin - <AUTHOR> http://www.reddit.com/r/Bitcoin/comments/1z1aix/technologically_clueless_grandstanding_senator/

<comment><USER2> Don't submit the reddit thread. Link to the original article.</comment>


Do Cellphones Cause Brain Cancer? - <AUTHOR> http://www.nytimes.com/2011/04/17/magazine/mag-17cellphones-t.html?pagewanted=all

<comment><USER2> no

</comment><comment><USER3> There was an amazing discussion about this some time recently on Reddit, and there was a lot of input from someone who had read all the studies with well backed, researched info, fully cited.

The short answer was - Probably Yes.

At least there was enough information to cause one to second guess holding a cellular radio against ones head multiple hours per day.</comment>