Archive for the ‘Clocking & Timer Circuits’ Category

Long duration timer circuit.

Description. This timer circuit can be used to switch OFF a particular device after around 35 minutes. The circuit can be used to switch OFF devices like radio, TV, fan, pump etc after a preset time of 35 minutes. Such a circuit can surely save a lot of power. The circuit is based on quad 2 input CMOS IC 4011 (U1).The resistor R1 and capacitor C1 produces the required long time delay. When pushbutton switch S2 is pressed, capacitor C1 discharges and input of the four NAND gates are pulled to zero. The four shorted outputs of U1 go high…

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Digital Stop Watch

Make a Digital Stop Watch Description A digital stop watch built around timer IC LM555 and 4-digit counter IC MM74C926  with multiplexed 7-segment LED display. MM74C926 consists of a 4-digit counter, an internal output latch, npn output sourcing drivers for common cathode, 7-segment display and an internal multiplexing circuitry with four multiplexing outputs. The counter advances on negative edge of the clock. The clock is generated by timer IC LM555. The circuit works off a 5V power supply. It can be easily assembled on a general-purpose PCB. Enclose the circuit in a metal box with provisions for four 7-segment displays,…

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