Npn Phototransistor Circuit. You can build this circuit with two standard 5mm red leds and any general purpose low power npn transistor bc108 bc182 or bc548 for example. A transistor amplifies current and can be used as a switch as explained on this page.
It is a special designs transistor which has a light sensitive base region. The collector is taken to the supply voltage via a collector load resistor and the output is taken from the collector connection on the phototransistor. The common emitter phototransistor circuit configuration is possibly the most widely used like its more conventional straight transistor circuit.
The common emitter phototransistor circuit configuration is possibly the most widely used like its more conventional straight transistor circuit.
The common emitter phototransistor circuit configuration is possibly the most widely used like its more conventional straight transistor circuit. Typical simulation model for an npn phototransistor circuit. You can build this circuit with two standard 5mm red leds and any general purpose low power npn transistor bc108 bc182 or bc548 for example. It works by allowing light to reach the pn junction of the device through the transparent opening.
