Simple PIR sensor circuit to drive a small motor

[Nevillet]

Hi All,

I'd like some help designing a simple circuit for driving a small DC motor.
The PIR module is a HC-SR501 which runs on 6V supply and outputs 2.4V when triggered. (Datasheet attached)

I'm not totally sure which motor I need yet but lets assume it'll be 12V and draw a maximum of 100mA.

Can somebody design me a simple circuit for me using something like a 2N3904?

I'm happy to include a relay if that makes sense.

Many thanks.


https://www.badcaps.net/forum/attach...1&d=1688920560

[harp]

Re: Simple PIR sensor circuit to drive a small motor

Something like that with TIP122:
https://electronics.stackexchange.co...-motor-circuit

[eccerr0r]

Re: Simple PIR sensor circuit to drive a small motor

Sometimes need to watch the difference between a PIR sensor and a PIR module, I suspect you have some sort of module here and you won't need an external op amp to deal with level detection (BTW, those circuits on stackexchange have one defect I can see right away, please don't use them!).

The output of the module you have appears to be TTL so you need to do something with a TTL signal. A TIP122 (NPN, Darlington pair) would work however (use it to pull down the negative lead of the motor to GND), just need to add a series resistor of 1KΩ or so to the base and use the TIP122 common emitter. No op amp needed. The sense (like if it's active high or active low) may need to be worked around but it appears that it's active high by default (high when something is detected.)

I have a different case, with my PIR "sensors" that I'm playing with are actually burglar alarm modules, so they have a small reed relay that opens a circuit when something is detected, so I need a totally different circuit to integrate it in an arbitrary system that's not a cut-to-open burglar detection system...

[Nevillet]

Re: Simple PIR sensor circuit to drive a small motor

I have some TIP120's to hand. Would the circuit below work or would it require modification?

https://www.badcaps.net/forum/attach...1&d=1688992175

[eccerr0r]

Re: Simple PIR sensor circuit to drive a small motor

probably will do something. You'll get a short delay but maybe that's what you want?

[Nevillet]

Re: Simple PIR sensor circuit to drive a small motor

I don't need the delay. Can I omit the cap?