PIR

[Electric-T]

Can the output on a PIR sensor be solid? I need it to power an npn transistor to switch a relay. But i cant have it pulsing and interupting the transistor therefore flipping the relay on and off. Once triggered i need it to stay on.

 

[Electric-T]

Ill post a schematic so you can see my dilemma

 

[Bluejets]

Most $10 pir's have a timer output for around 30 minutes max. If you need more, add another timer.

 

[Electric-T]

Heres my model. https://www.amazon.com/HC-SR501-Sensor-Module-Pyroelectric-Infrared/dp/B007XQRKD4
If its 30 minutes thats plenty for my design. Thanks

 

[Bluejets]

The units I was referring to are exterior mount 220v. What you have is a pir module which will need additional circuitry or equipment. Might be a good idea for you to check the specs. I did, in the link you provided. See how you go then....

 

[Harald Kapp]

Once triggered i need it to stay on.

Use an S-R flipflop. You can build it from discrete components or use an integrated logic circuit. Teh PIR sensor would be connected to e.g. the SET input such that after the first pulse from teh sensor the output of the flipflop is active and stays active regardless of the input.
You'll have to think about how the flipflop is to be Reset, otherwsie it will be on forever (at least as long as the power supply lasts).

If you want the output of the circuit to be active for some time only, use a monostable multivibrator. A very simple circuit is e.g. based on the venerable 555 timer ic.

 

[Electric-T]

The units I was referring to are exterior mount 220v. What you have is a pir module which will need additional circuitry or equipment. Might be a good idea for you to check the specs. I did, in the link you provided. See how you go then....

Use an S-R flipflop. You can build it from discrete components or use an integrated logic circuit. Teh PIR sensor would be connected to e.g. the SET input such that after the first pulse from teh sensor the output of the flipflop is active and stays active regardless of the input.
You'll have to think about how the flipflop is to be Reset, otherwsie it will be on forever (at least as long as the power supply lasts).

If you want the output of the circuit to be active for some time only, use a monostable multivibrator. A very simple circuit is e.g. based on the venerable 555 timer ic.

Thank you ill look into it