Built a power supply but output isn't smooth enough?
You most likely aren't measuring the ripple correctly. That's not to say that there isn't some noise on the output, but common-mode pollution of the scope measurement due to ground-lead pickup is very common when you're dealing with switching converters.

You need to use a probe with a very short ground lead and need to have bandwidth limiting enabled on your scope channel.

Please update your question with the results of this experiment (as well as a photo of your breadboard) and we can proceed further.