Infa-Red Remote Control

I have received a number of emails requesting schematics for infa-red remotes. So here is one. This remote transmits a tone using an infa-red LED. This tone is decoded by the receiver. Since the receiver only switches when it "hears" the tone, there are no accidental activations.

Schematic For Transmitter

Schematic For Receiver

Parts

Part Total Qty. Description Substitutions R1 1 22K 1/4W Resistor R2 1 1 Meg 1/4W Resistor R3 1 1K 1/4W Resistor R4, R5 2 100K 1/4W Resistor R6 1 50K Pot C1, C2 2 0.01uF 16V Ceramic Disk Capacitor C3 1 100pF 16V Ceramic Disk Capacitor C4 1 0.047uF 16V Ceramic Disk Capacitor C5 1 0.1uF 16V Ceramic Disk Capacitor C6 1 3.3uF 16V Electrolytic Capacitor C7 1 1.5uF 16V Electrolytic Capacitor Q1 1 2N2222 NPN Silicon Transistor 2N3904 Q2 1 2N2907 PNP Silicon Transistor Q3 1 NPN Phototransistor D1 1 1N914 Silicon Diode IC1 1 LM308 Op Amp IC IC2 1 LM567 Tone Decoder LED1 1 Infa-Red LED RELAY 1 6 Volt Relay S1 1 SPST Push Button Switch B1 1 3 Volt Battery Two 1.5V batteries in series MISC 1 Board, Sockets For ICs, Knob For R6, Battery Holder RELAY 1 6 Volt Relay

Notes

1. To adjust the circuit, hold down S1 while pointing LED1 at the receiver. Adjust R6 until you hear the relay click.
2. You can increase range by using a high output LED for LED1.
3. Bright light will stop the receiver from responding to the transmitter.
4. There is an error in the schematic. There shuold be a 1 megaohm resistor between pin 3 of IC1 and ground. This provides a 0 volt reference to bias the IC.