Easy

IR Remote-Control Tester

An infrared-sensitive phototransistor detects the invisible pulses from any remote control and makes them visible through an ordinary LED — useful for checking whether a remote "still works" before throwing it away.

Circuit Diagram

+9V IR remote → R Phototransistor 940nm base R Q BC547 C → LED E → GND 220R LED Any IR remote signal makes the LED flicker when a button is pressed

How to Build It

  1. Place the infrared-sensitive phototransistor (940nm) on the breadboard.
  2. Connect the phototransistor's collector to the positive rail through a resistor.
  3. Connect the phototransistor's emitter to a BC547 transistor's base, through a resistor.
  4. Connect the BC547's collector to an LED and then to the positive rail.
  5. Connect the BC547's emitter to GND.
  6. Power the circuit, point any remote control at the phototransistor and press a button — the LED should flicker.

Bill of Materials

ProductCodeQty
Phototransistor — 1
LED (3/5/10mm, SMD, power) l-934ID-12V 1
Resistor DR47K-8/9 2
Transistor (incl. IGBT) — 1
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