I am currently measuring the movment of my stepper motor by counting the switching of the electrical pulses to give calculated coordinates. I would like to set up a simple optical encoder to physically count the number of revolutions using a Darlington photo-interrupter. I have built the circuit as per the datasheet (rapidonline.com/pdf/58-0310.pdf). The cicuit produces two states 0.12 and 0.6v. I had hoped to drive a reed relay to provide a digital input but do not have the 5v output to drive it. Are there any wizards out there who could provide a simple solution to interface this circuit. I would be grateful for a diagram as I am new to electronics.
The photodarlington allows a current up to 40mA.
You could look for a small 5V reed relay which draws less than 40mA.
If you connect one side of the relay coil to the collector of the photodarlington and the other side of the coil to the +5V, it could work.
Don’t forget to put a diode (e.g. 1N4148 over the relay coil, cathode to the +5V).
If the pulses are not too fast, the relay will probably do fine.
Make sure the led of the photo-interrupter is properly driven (suitable resistor in series).
Thanks for your advice, the circuit is now opering ok. I think that I will use the same circuit as left and right hand limits for the x and y axis of my plotter instead of micro switches.