The circuit diagram shown in Fig.1 uses a PNA4602M IR detector to receive an IR signal from the remote control. It’s a neat device, which contains an IR receiver, amplifier and demodulator together in a single 3-pin package, and it’s normally used in circuits where you want to decode an IR remote control signal.
The way the circuit (Fig.1) works is as follows. When there is no IR coded signal present, the output pin of IC1 remains high. This high signal is fed to the trigger input of the 555 timer (IC2), which being configured as a monostable timer, prevents the timer operating.
Whenever you briefly press any key on the old remote control its IR signal is received by IC1 and output pin 1 produces a train of fast moving high and low pulses, which mimic the IR signal code sent by the remote control. We are not interested in this code, but as soon as the signal switches low it triggers the monostable timer IC2 and its output pin 3 goes high for a short period of time, set by resistor R2 and capacitor C2.
The 555 timer (IC2) basically acts as a debounce circuit, and its output is fed into the clock pin (CLK) of the 4013B dual Dtype flip-flop IC3. Only one half of the chip is used in this application, and it is configured as a bi-stable flip-flop.
An initial clock signal into IC3 causes its output pin 2 to go high, and it remains high until another IR signal is received. To switch the output off you simply press any button on the old remote control again and the above operation is repeated, but this time IC3’s output is switched off and remains off until another signal is received. The output basically acts as a toggle switch.
The output pin in this circuit drives an LED to show the output status. However, the output could be easily interfaced to drive a transistor and relay to switch a higher load. The circuit could then be used to remotely switch equipment in your garage, shed or office.
Don’t forget that you need to use the circuit in an area where IR remote controls are not normally present, because the circuit will operate with virtually any IR remote control. Capacitor C1, positioned across the output of the IR receiver (IC1), stops spurious triggering from artificial lighting, which can occur if this isn’t in place.
Schematic:
Components Required:
| Components | values | quantity |
| R1-R2 | 100k ohm | 2 |
| R3 | 270 ohm | 1 |
| R4 | 390 ohm | 1 |
| C1-C2 | 4.7uF/16v | 2 |
| LED1-LED2 | Red LEDs | 2 |
| IC1 | PNA4602M | 1 |
| IC2 | 555 | 1 |
| IC3 | 4013 | 1 |
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