This is not an Arduino question, hope that is OK. I have a automatic pet feeder that uses a Fairchild M0C70P1 integrated transmitter/ receiver to stop motor once dish has turned one feeding slot. The IR diode side has failed and I am trying to replace the device with an EK8443 IR Emitter/Receiver pair which I purchased on Amazon. I have not found a way to identify how to orient the two devices on the circuit board where the M0C70P1 was soldered. Any way to identify the polarity of the devices? The legs of each device are different length ... is that the magic? Any help would be appreciated.
(I suppose I could try the 4 possible orientations ... where is that breadboarding kit from college ...)
Plese upload pictures of the old part.
Google doesn't know what a MOC70P1 is.
I have seen many burned out LEDs in slot sensors, because of too high designed LED current. Maybe you only need to replace the IR LED.
A working IR LED has about 1.3volt across when powered.
Leo..
I don't think your replacement will work. The original's output is a phototransistor. I don't think you can replace it with a photodiode. Or you might find a replacement for the original part. Look on Digikey for:
photointerrupter - slot type - transistor output.
In any case, I think for all diodes the long lead is the anode.
The IR LED should measure about "1.2" one way on a DMM set to diode measurement.
The cathode has a flat part on the LED body and the leg is usually shorter.
The MOC70P1 has a bevelled top on the LED side.
Getting new slot sensor seems a lot easier.
Leo..
I might have found a replacement optical slot sensor on Amazon. Ordering. Will know tomorrow But what will I do with the 18 that I don't need!
I discovered that the diode side was blown by accident ... I noticed that when I had the tray in place it would turn forever. If I removed it, the motor would not advance at all. If I put a piece of plastic between the diode and receiver it would run until I removed the plastic. Turns out that was happening because of ambient light. Then I noticed that if I pointed a flashlight into the slot area it would advance properly, one feeding slot at a time. I rigged a LED light strip so it would light when the motor engaged and when the slot in the tray (that is what that slot was for!) passed the slot in the M0C70P1 part it would stop (and the light would go out). I have two of these feeders that have the same problem ... guessing the diode burned out. One is working with my kludge (happy cat) and the other I am trying to fix a different way. Also hooking up to a 5V power supply to see if I can take batteries out of the maintenance.
But what will I do with the 18 that I don't need!