On/Off Remote Control For Two Appliances

This microcontroller-less remote control circuit operates by translating infrared signals from a standard remote into discrete switching actions using purely analog and digital logic components. Power is supplied by a 12V-0-12V center-tapped transformer paired with 1N4007 diodes for rectification and a 7805 voltage regulator IC to deliver a steady 5V DC rail to the logic circuitry. When an infrared signal is emitted toward the TSOP1738 IR receiver, it demodulates the carrier frequency and outputs a corresponding digital pulse train. This signal is conditioned using components like BC557 and BC547 transistors alongside 1N4148 switching diodes to drive the clock input of a CD4017B decade counter IC. Each received pulse advances the counter's active output state sequentially. Through the arrangement of transistors and supporting resistors, these sequential steps toggle the states of two 12V electromechanical relays (RL1 and RL2). The relays act as electrically isolated switches capable of routing higher-voltage AC mains power to external appliances, while an LED provides visual feedback of the active operational state.