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Clap Controlled Electronic Switch by 555 Timer and 4013 D Fl

2014-12-16 20:20  
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This is a 32 channel infrared remote controller circuit fundamentally includes key pad, decoder, transducer stage, an output and a battery. Circuit is like a pocket calculator in size. Commands are formed by using 8 × 4 matrix with 32 switches.

Be aware that only one switch functions at one time and during one command is been generating, input circuitry is irresponsive to the other commands.

Every key pad button generates 5 bit binary code and IC1 sends this code to the IR leds through D1 and D2 diodes. Code is shaped from 6 pulses with 5 gaps. Pulse position modulation –PPMtechnique is used for transferring data. Data information occurs at gaps. For logic 0, long gap, for logic 1 short gap is generated

Pulse and gap lengths are calibrated by using P1 potentiometer.

Length ratio between logic 0 and logic 1 is (1.5 / 1). Pulse length between two 54ms code word is about 3ms.

Transmitter transmits infrared light only when IC1’s 3 numbered pin is high.

SL490 includes an auto stand-by circuitry. When the buttons are not used for a while, IC will swich to stand-by mode and stand-by current will be 6uA.

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This electronic switch allows you to control an electronic device by only clapping your hands twice. It is based on three integrated circuits; 741 Op-Amp, 555 timer, and 4013 dual D flip-flop.

A 9V battery is ample to operate the circuit.

When you first clamp your hands, mic detects the sound and triggers the 555 timer via the operational amplifier. The timer stretches the signal and applies it to the clock input of the flip-flop. Because of the three state arrangement of the flip-flop , one more clamp is needed to change the output state. Second clamp sets the flip-flop output to high and this forward biases the 2N2222BJT. Relay closes so the device connected to the relay switches on. Same procedure applies for the opposite. When you clap your hands twice, relay closes and turns off the device connected to it.

R3 trimpot adjusts the sensitivity of the circuit. You should turn it till the room noise does not effect the switch operation.

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