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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.
| 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 |
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.