How can I prevent HDMI 5V (55mA) from entering a circuit?
Thanks to all the suggestions. On the advice of some of the replies, I checked another brand of the same type of device, and it seems the newer ones are HDMI compliant, since there is no 5V &quot;backfeeding&quot; to the main power source. The original models were cheap $5 versions on eBay, the HDMI compliant versions are $70(!!!)
This has fixed my problem, thanks