Most PIR sensors should run on 3.3V; most likely yours is one of those 'jelly bean' units available from dozens of sellers on Ebay/Amazon.
If there are 3.3V devices in your clock, there will be a 3.3V source somewhere; In my case I provide +5V to a RasPi, but it's onboard 3.3V regulator's output is exposed, so it's used to power the PIR sensor, which requires less than 1mA of current. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/f313bf55-526f-4b6a-b132-57107357262d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.