d_a_parker Posted August 4, 2021 Report Share Posted August 4, 2021 Hey everyone, I recently acquired an original Big Trak (1979) but it has a few issues. I have traced the biggest problem to the fact that the wheel sensors are broken. There's a small circuit board with an emitter and receiver on it which look like LEDs, but one of the two is literally cracked in half. Looks like a fairly simple repair if I knew what the specs on these parts were, but I can't seem to find any information on them anywhere. Does anyone here know what type of emitter and receiver these are? If not, anyone know of another place I could look for help? Thanks! Quote Link to comment Share on other sites More sharing options...
RickR Posted August 4, 2021 Report Share Posted August 4, 2021 I'm not sure. There's no info on the parts themselves, or on the circuit board? I didn't even know the Big Trak has emitter/receiver. It thought it just had step motors that turn on/off for a certain length of time. I have a working Big Trak that will be for sale soon. Do you need any pictures or info from mine? Quote Link to comment Share on other sites More sharing options...
RickR Posted August 4, 2021 Report Share Posted August 4, 2021 Here's some good info that may help you. I learned something new today, so thanks for posting. It's a pretty ingenious design! https://www.robotroom.com/BigTrak.html Quote Link to comment Share on other sites More sharing options...
d_a_parker Posted August 4, 2021 Author Report Share Posted August 4, 2021 That's actually the same site I found when I was first looking into this, but they just refer to these as "emitter" and "detector". I know it's an infrared LED and it looks like maybe it's driven by 6V DC, but I have not been able to find the exact specs on these parts anywhere. The board itself is not labeled. Maybe I'll just need to buy an IR emitter and detector pair and see what happens. Thanks! Quote Link to comment Share on other sites More sharing options...
RickR Posted August 5, 2021 Report Share Posted August 5, 2021 I can't find it either. Good luck. My guess is that any set will do. In any case, I had a lot of fun reading that site. So thank you for posting. Quote Link to comment Share on other sites More sharing options...
Justin Posted August 5, 2021 Report Share Posted August 5, 2021 I think @Willie! has some good experience with the Big Trak Quote Link to comment Share on other sites More sharing options...
d_a_parker Posted August 5, 2021 Author Report Share Posted August 5, 2021 Thanks. I've been looking online but haven't found an IR LED and photodiode pair that both look like the ones in the Big Trak. I'm hesitant to remove the old ones and put in something totally different, without at least knowing if the specs on those parts are similar. It's crazy that nothing is labeled in that thing. An interesting project, though! Justin 1 Quote Link to comment Share on other sites More sharing options...
RickR Posted August 5, 2021 Report Share Posted August 5, 2021 Maybe this one? https://www.ebay.com/itm/220907079881?hash=item336f1688c9:g:AcAAAOSw1qhcDJzS Quote Link to comment Share on other sites More sharing options...
d_a_parker Posted August 5, 2021 Author Report Share Posted August 5, 2021 13 minutes ago, RickR said: Maybe this one? https://www.ebay.com/itm/220907079881?hash=item336f1688c9:g:AcAAAOSw1qhcDJzS Maybe! That's the best possibility I've seen so far. The problem is, I'm not 100% sure if the Big Trak sensor is a photodiode or photoresistor, and there's a difference. One needs a voltage applied and the other does not. I'll probably need to pull the board from the Big Trak and do some testing to see if I can figure out exactly what's on it. Quote Link to comment Share on other sites More sharing options...
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