905Views4Replies

Author Options:

how do you get a photo sensor to turn on in the dark instead of in the light? Answered

is it possible, I am trying to do this so I can make a laser trip wire, but it turns off in the dark instead of in the light.

Comments

The forums are retiring in 2021 and are now closed for new topics and comments.
0
miiwii3
miiwii3

11 years ago

plug it into a transitor that should reverse it. but i can't remember if it is npn or pnp get back to u on that.

0
XOIIO
XOIIO

11 years ago

nice! I just finished a laser tripwire! Super easy way is to go to a dollar store and buy a garden led light that turns on an night. Then just take out the circuit and mid it for a buzzer/ more LEDs anything that you want to hook up. Works perfect for me. Hope I helped!

0
kelseymh
kelseymh

11 years ago

If the sensor has separate pins labelled "NC" (normally closed) and "NO" (normally open), just swap your lead from the one to the other. Otherwise, take the output leads and use a relay to do the inversion. You'll need to supply power to the relay. Or use a logical NOT gate.