Search found 7 matches
- Thu Feb 19, 2009 2:55 am
- Forum: Do-It-Yourself
- Topic: Phototransistor sensitivity question
- Replies: 12
- Views: 21115
Re: Phototransistor sensitivity question
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...
- Tue Feb 17, 2009 11:28 pm
- Forum: Do-It-Yourself
- Topic: Phototransistor sensitivity question
- Replies: 12
- Views: 21115
Re: Phototransistor sensitivity question
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
- Tue Feb 17, 2009 9:56 pm
- Forum: Do-It-Yourself
- Topic: Phototransistor sensitivity question
- Replies: 12
- Views: 21115
Re: Phototransistor sensitivity question
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.
- Tue Feb 17, 2009 12:13 pm
- Forum: Do-It-Yourself
- Topic: Phototransistor sensitivity question
- Replies: 12
- Views: 21115
Phototransistor sensitivity question
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...
- Tue Feb 17, 2009 10:02 am
- Forum: Do-It-Yourself
- Topic: How *should* timers respond to ties?
- Replies: 5
- Views: 10005
Re: How *should* timers respond to ties?
@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...
- Sat Feb 14, 2009 1:39 pm
- Forum: Do-It-Yourself
- Topic: How *should* timers respond to ties?
- Replies: 5
- Views: 10005
Re: How *should* timers respond to ties?
@gpraceman, that's perfect! Thanks.
- Sat Feb 14, 2009 12:36 pm
- Forum: Do-It-Yourself
- Topic: How *should* timers respond to ties?
- Replies: 5
- Views: 10005
How *should* timers respond to ties?
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...