Periodic Timer


Posted on Jul 20, 2012

A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes. This timer circuit is similar to the 5 to 30 minute timer except that when switch S1 is closed, the on/off action of the circuit will continue indefinately until S1 is opened again. A 7555 time and low leakage type capacitor for C1 must be used. The 6 way rotary switch S3 adds extra resistance in series to the timing chain with each rotation, minimum resistance point `a` maximum point `f`.


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

The 7555 is wired as an equal mark/space ratio oscillator, the timing resistor chain R1 to R6, being connected back to the output of the timer at pin 3.The output pulse duration is defined as:- T = 1.4 R1 C1 This gives on and off times of about 37




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Audio Millivoltmeter
Rock Face effect for guitars
Low Loss Step Down Converter
lithium ion Battery management circuit for Nokia BL-4C / 5C Li-ION batteries
schematics Use of ground symbols in circuit diagrams
mic 702 mictronics schematic diagram
20w rf fm amplifier circuit
Television Camera Experiments
Tuned Radio Frequency (TRF) Receiver
Variable PSU
16 Step Sequencer
Arduino GH-2 integration for time lapse
ACC FC-1 Remote Base Interface circuit
UTP cabel tester



Top