Timer Circuit Using Logic Gates. This nand timer is a delay on type where the led remains off until the capacitor c has sufficient charge. R1 60 1 1 x 1000 μf r1 55k.
60 sec 1 1 x r1 x 1000 μf. First part of design involves designing the astable multivibrator arrangement of 555 timer here the required time period is 1 second. Hence set the value of potentiometer to 55k and your timer will be set for 1 minute.
Digital stopwatch circuit design.
Upon closing the switch the capacitor c begins to charge through r1 and since this is a large capacitor of value 0 1 f it takes some time to charge. On receiving this trigger the input of the 5 not gates are initially held at logic zero because the capacitor grounds the initial trigger via the 2m2 pot. Looking at the figure initially because of the resistor r1 and r2 the whole system remains stationary maintaining a logic high output. I seek a simple transistor based timer circuit for use in a car.
