Derby Talk

IR emitters? Ok, actually I have a set of those too. Am I reading the datasheet on that right? 100mA? That's a bit of a jump from the 20mA LEDs, but not a problem for this circuit. Maybe I should just get over my reluctance to use IR sensors. I actually have IR emitters and IR-only photodiodes (with...

Ok, I'll give that a try. I liked the idea of the individual lights mostly because I thought it looked better, but that's ultimately not nearly as important as the finish line sensors actually functioning

They're actually designed for visible light, although they peak in sensitivity around the red end of the spectrum. I have some IR emitters too, but was shying away from IR, though, because it's a lot harder to aim a light you can't see.

I seem to be running into a problem with my finish line sensors. I'm using a set of Osram SFH314 phototransistors (Digi-Key 475-1081-ND) set into 1.5" deep black tubes under the track, with ultra-bright LEDs overhead (about 6" over the track). I'm having a tough time getting the sensors to...

@SlartyBartFast: yes, that's a very good point. I think it's easy to get carried away with reporting "accuracy" and not taking into account the point where you're no longer measuring the cars as much as the sensor reaction times (etc.). In my project, the microcontroller (a PIC in this cas...

@gpraceman, that's perfect! Thanks.

I'm in the middle of scratch-building my own timer (yeah, I know I'm insane, but it's a hobby) and at this moment (with the big race on Tuesday... no pressure or anything...) I'm working on the part of the firmware which reports back the race results to the computer. Ordinarily I'd just round off th...