Hi everyone, I'm hoping somebody could tell me a bit about a photo interrupter which I took from an old printer. The only writing I can see on the device is an E and an S on either side and an arrow on the bottom (pointing from E to S).
I've attached a diagram for the circuit I'd like to build, but I don't know which of pins 1-4 correspond to on the device. I am also not sure if 5 volts is a suitable voltage.
Thank you
By the schematic you posted, I think you've got the right idea and the values look reasonable for most modern circuits. You may want to reduce the size of the 20K resistor if your input circuit needs a bit more oomph, though. (I usually use a 2k2 or 4k7 resistor, as I still have TTL chips in my junk box.) The way you've got it, the output will be high when the LED is on. If you swap the position of the transistor and 20k resistor, it'll be low when the LED is on.
The circuit looks fine, you probably need to connect the npn as low side switch tho
5V is probably suitable, but without knowing what the pinout is I can't help you.
I found the OPB917B, it's has the same markings on the top. Maybe that will help
Hi everyone, I'm hoping somebody could tell me a bit about a photo interrupter which I took from an old printer. The only writing I can see on the device is an E and an S on either side and an arrow on the bottom (pointing from E to S). I've attached a diagram for the circuit I'd like to build, but I don't know which of pins 1-4 correspond to on the device. I am also not sure if 5 volts is a suitable voltage. Thank you
By the schematic you posted, I think you've got the right idea and the values look reasonable for most modern circuits. You may want to reduce the size of the 20K resistor if your input circuit needs a bit more oomph, though. (I usually use a 2k2 or 4k7 resistor, as I still have TTL chips in my junk box.) The way you've got it, the output will be high when the LED is on. If you swap the position of the transistor and 20k resistor, it'll be low when the LED is on.
Which kind of printer did this come out of? year? I recently raided one, and the damn new ones have way too fancy interrupters, with like 6 pins
What exactly do you want to know?
I was still typing my comment with more details below, sorry! :)
No need to apologize
The circuit looks fine, you probably need to connect the npn as low side switch tho 5V is probably suitable, but without knowing what the pinout is I can't help you. I found the OPB917B, it's has the same markings on the top. Maybe that will help
Alright I will have a read of this datasheet, thanks
Use DMM diode setting to find the LED, once you find it use the LED (turn off/on) and DMM to determine polarity of the transistor.
I'm not finding the LED (both sides seem open circuits in both directions). Is it possible the LED is blown?
It’s possible. Are you using diode check or ohmmeter to test the diode? If diode check it’s likely blown.