PIR Sensor analog value oscillation?

[silverlock]

Thanks for the additional replies.

@bluejets

Non-isolated supplies can be all of the above.
Normally designed to be inside of a purpose design self contained system.
Bring anything from them into the real world and a fault results in mains supply on the low voltages.

Can you give me an example of a better component I could use to get from 110VAC to 12VDC in this application?

@Railroader

Powering the Arduino with 12 volt and tapping the Arduino 5 volt to power a relay board is wrong.

This is another thing that I have read conflicting opinions on. In my limited experience I haven't had problems with the Arduino powering the relay board, but my experience is definitely limited. I'll re-work this.

Paul_B: Are you saying that the only acceptable ways to power an Arduino Uno are by USB or by feeding already-regulated 5VDC into the 5V pin? I don't mean to be difficult or ungrateful for the advice, but that goes against a lot of what I've read. All of the 'how to power an Uno' articles list the barrel jack and Vin as acceptable alternatives.

@dave-in-nj

the PIR and Sound module draw very little power. they could be powered by the Arduino.
the speaker might be better with a separate power supply.

How would you connect the PIR and audio board to the Arduino to get power from it? I thought I had an idea of how this would be done but some of the other replies I got have made me doubt what I thought I understood.

@dave-in-nj

ps : if you had a second post on pirate Halloween, you should delete it. this is very well presented and has very little room for guess work.

I missed replying to this earlier - I haven't made any posts anywhere else about this project.

Based on the feedback I've gotten, I've updated my design to this:

So far the only part of the udpated design I've tested is the PIR - it is reliably triggering the Arduino only when there is motion.

@Wawa

Did someone already tell you that a PIR sensor outputs a digital signal, not an analogue value.
Leo..

Not explicitly, but I kind of knew that. My final sketch is based on a project I found online for an Arduino-based animatronic controller and that design treats its PIR as an analog input. It samples the analog value as a rudimentary test to see if a PIR is present on a certain PIN. I've tried this both ways and gotten the same results.

@anon35827816

HOWEVER, you should make sure that the GND on the output side of the DC-DC converter is connected to GND on the input side. So the 12V GND must be connected to the 5V GND.

I have not directly connected the LED driver Output- to the Output- of the DC-to-DC converter, but when I test for continuity between those two points they measure as connected. Does this mean that they already share a common ground or am I missing something?

Thanks,
Mike