Simple Infra-Red Detector

Circuit description:

This circuit is a simple IR detector for testing IR remote controllers. The circuit is based on one phototransistor which receives the IR beam. The NPN transistor works as an amplifier which feeds current to the led. When this circuit detects IR or light, the LED is on. So you need to shield the phototransistor from ambient light if you don't want to do your tests in the dark. The best way is to fit the phototransistor in a small black tube.

Component list:

Q1 BP109 (or similar phototransitor)

Q2 BC238C or BC547

D1 RED LED

R1 390 ohms 0.25W