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Discussion Starter · #1 ·
I was thinking to use these to activate props that have a Demo lead and button. Trouble is, they aren't simple relays but actually output about 2.9 volts at very low current. Maybe one of you electronics gurus could tell me how I might use these?

 

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There are several parts to your problem.

The first is the PIR. You can convert the output from voltage to an "open collector" with one resistor and an NPN transistor. This gets you a signal that connects to 0V (power -ve) when the PIR is triggered. I did a write up a few years ago on modifying a different type of PIR: https://www.da-share.com/misc/hc-sr505-pir/

The second is how the demo button input is done electrically. Sometimes one wire is 0V (power -ve) and the other is the actual trigger. This is the best type as you can use it with an open collector output. If not, you'll need to use a small relay or optocoupler to isolate the signals.

The third is how the demo button works. If it's the typical try-me type, one press starts the demo but a second press during the demo stops it again. This means you really need to lock out the PIR signal for the duration of the prop action to avoid is stopping part way through. Now you're getting into prop controller territory so it can make sure the prop is only triggered once each time.

So as you can see, it might not be as straightforward as you hoped.
 

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Discussion Starter · #3 ·
There are several parts to your problem.

The first is the PIR. You can convert the output from voltage to an "open collector" with one resistor and an NPN transistor. This gets you a signal that connects to 0V (power -ve) when the PIR is triggered. I did a write up a few years ago on modifying a different type of PIR: https://www.da-share.com/misc/hc-sr505-pir/

The second is how the demo button input is done electrically. Sometimes one wire is 0V (power -ve) and the other is the actual trigger. This is the best type as you can use it with an open collector output. If not, you'll need to use a small relay or optocoupler to isolate the signals.

The third is how the demo button works. If it's the typical try-me type, one press starts the demo but a second press during the demo stops it again. This means you really need to lock out the PIR signal for the duration of the prop action to avoid is stopping part way through. Now you're getting into prop controller territory so it can make sure the prop is only triggered once each time.

So as you can see, it might not be as straightforward as you hoped.
A lot to think about. Thanks.
 
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