R1_____________470K 1/4W Resistor R2______________47R 1/4W Resistor D1______________LED (Any dimension, shape and color) Q1____________Infra-red Photo Transistor (Any cheap type) Q2____________BC327 45V 800mA PNP Transistor SW1____________SPST Toggle or Slide Switch (Optional, see Note) B1_______________3V Battery (2 x 1.5V AA, AAA or smaller type Cells in series)
A very simple device allowing a quick check of common Infra-red Remote-Controls can be useful to the electronics amateur, frequently asked to repair or test these ubiquitous devices.
A reliable circuit was designed with a handful of components: the LED will flash when any of the Remote-Control pushbuttons will be pressed. The side of the Remote-Control bearing the IR emitting diode(s) must be directed towards the Photo Transistor (Q1) of the checker circuit: maximum distance should not exceed about 20 - 25cm.
- Current drawing of the circuit is less than 1mA when the LED illuminates and 0mA when no signal is picked-up by the Photo Transistor: therefore, SW1 can be omitted.