Infrared "slotted switch" sensor

Hi, been a while... do any of you remember me?

Anyway, I was looking at **broken link removed**... I know it's not complicated, but that's sorta what I want to do. I would need to modify it a bit. For one, I need it to be held high while the beam is undisturbed, and pull "Vout" to ground when interupted, instead. I also need to sextuple the circuit... I need six emitters, and 6 detectors, and I need to design it in such a way, to where if ONE on the six beams is interupted, it will pull ONE terminal to ground. Do I need to use OR gates for this? It's basically like a security system. If any one of the six beams is interupted, it pulls low, and triggers an alarm. 'Cept most security systems probably go high, but that's not the point.

Can anyone give me a circuit for this, or point me in the right direction to make one myself? Thanks.

Rain

P.S. Did you miss me? 8)

Just parallel all the transistors, and use a single 4.7K pullup - this is the whole point of using pullup resistors!.

Who are you? :wink:

It should do what you want, (hold high until the beam is blocked). OR gates would work as well. Then you could connect the output of the OR gates to an SR latch, that way once one of the sensors is triggered, you would have to reset the latch for the alarm to turn off.

I just used a similar circuit as an optical encoder for my robot (microcontrollers final project). I also discovered that those 5mm LEDs fit perfectly into the holes of LEGO blocks (so if you need a convienent way to mount them...).

I would need to modify it a bit. For one, I need it to be held high while the beam is undisturbed, and pull "Vout" to ground when interupted, instead.

Click to expand...

just invert the Vout use another npn / or use a phototrans pnp type