Timer circuit

Posted on Dec 23, 2012

A wide rage auto turn OFF timer covering 1 minute to 20 hours in three ranges with S1. As soon as power is applied to the circuit the IC1 [555] starts to oscillate happily and feeds clock pulses to the IC2 [4017]. The IC2 [4017] and IC3 [4020] give a combined count rate of 81920 before the output of the IC3 [4020] goes high and turns Q1 on. With pot RV1 adjust the Time.

Timer circuit
Click here to download the full size of the above Circuit.

Part List R1=2.2Kohm C1=120nF 63V polyester IC2=4017B R2=39Kohm C2=1.2uF 63V polyester IC3=4020B R3=1Mohm C3=100nF 63V Q1=BC214 R4=27Kohm RV1=470Kohm pot. S1=2X3 SEL SWITCH R5=12Kohm D1-2=1N4001 S2=Push button no R6=6.8Kohm IC1=LM555 RL1=12V >120ohm Relay

Leave Comment

characters left:

New Circuits



Popular Circuits

McCAD PCB software
PIC16F84A Gas Detector
Touch Switch
807 and 1625 Valves as power amplifiers
Lead Acid Battery Charger III
Simple color organ
LM555 interlocked monostable timer circuit
LM139 Measure delay generator Schematic Diagram
rf digital
stepper motor driver circuit diagram
3W FM Transmitters
IC Multiplexers
SPI Interface Big 7-Seg LED
Stepper Motor Driver
Interfacing to Sony Cameras
Gas stove flame alarm circuit