[555 timer Relay driver with TTL input]

Hi HarryA ,

Yes I think using a transistor / cap to pull pin 2 low is the only way to do it. My relay resistance is 370ohms.

 

[555 timer Relay driver with TTL input]

Hello,

I want to drive a 12v relay off a 555 timer after being triggered by a 12v PIR sensor. The sensor has a 3.3V TTL output which goes HI when the sensor is triggered. Once the sensor turns off the TTL output returns to 0V.

-I  want the Relay to turn on for up to 1 minute (can be adjustable) after being triggered. 

I think I need a monostable circuit & I know the trigger needs a low input, but I'm unable to figure out how to put this together.
Is anyone able to fill in the gaps or provide a known working circuit?