Reading a photo transistor with a voltmeter

A project log for Ink and paper MCU programmer

Solving the egg and chicken problem with paper, leds and phototransistors

ftreganftregan 11/19/2016 at 11:460 Comments

I ordered some phototransistors, lots them, ordered again, and made this simple circuit :

If you read voltage between the phototransistor and resistor when the led cast light to the phototransistor, it read a low voltage (about 0.5V), when there is no light, it read almost 5V. Easy.