This is an infra-red (IR) toggle switch which will work with any button on any modern remote control module. Push any button of your remote control unit and the relay in our Kit will turn on. Push any button a few seconds or hours later and the relay will toggle off. Following is the schematic diagram :

Infra Red Switch Circuit Diagram using CK1600 IR Toggle Switch (click to enlarge)

Infra Red Switch Circuit Diagram using CK1600 IR Toggle Switch (click to enlarge)

Circuit Description. The Kodenshi IR receiver module in our Kit detects and decodes the 37.9 kHz input as a train of negative pulses. These negative pulses are inverted by transistor Q1. Then these positive pulses are converted to a single pulse by the network R4, D1, R5 & C2. The positive pulses on the collector of Q1 charge capacitor C2 via resistor R4 and diode D1. The charging time is approximately 12.5msec (R4 x C2). During the low time between pulses the collector of Q1 is low and C2 begins to discharge. However, the discharge path is via R5 because D1 is now reverse biased and therefore non-conducting. The discharge time is about 0.5 sec (R5 x C2). Since the frequency of the received pulses is much faster than the discharge time of the capacitor C2, the capacitor cannot fully discharge before the next IR pulse train is received. The charging cycle of capacitor C2 provides the rising edge needed to clock the flip-flop.

The flip-flop (FF) is a D-type. The voltage level at the D input is transferred to the Q output on the rising edge of the clock pulse. Since we are using the inverted /Q output, a low level at D will cause /Q to go high and a high level at
D will cause /Q to go low. The output of the FF can only be changed with the next rising edge of the clock input.

The /Q output which drives the relay is also fed to the D input via resistor R6 & capacitor C3. This allows the output of the FF to toggle between high and low with every clock pulse received. With /Q high, C3 is charged via R6. After about 1.2 seconds (R6 x C3) the D input will rise to a digital high level. This high will be transferred to the output on the next clock pulse. This will cause /Q to go low, thus discharging C3. After 1.2 seconds the D input will go low ready for the next clock input.

A feedback delay between the output and input is necessary to keep the input stable while clocking the FF. The delay time chosen (1.2 seconds in this case) determines how quickly the relay can be toggled.

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