Ok, I'm building a photogate/timer circuit to trigger a flash and I think I may have a faulty phototransistor. If I understand correctly, when my IR beam is broken (object between IR emitter & phototransistor) the voltage across the phototransistor should rise... correct?
I built a simple circuit w/ power supply, resistor, & phototransistor and then checked voltage as I (un)covered the phototrans from my desklamp light and there was no voltage change (9.00V... unchanged to 2 decimal places). I'd assume that your average desk lamp emits IR as well as visible light.
P.S. My timer circuit works beautifully. Just turning a pot adjusts delay from nearly instantaneous all the way up to about 0.5s. I suppose I could calculate the delay by measuring resistance across the pot... but trial & error seems to be working fine so far.
If/when I get this working... expect some cool pictures.
