This is basically a flasher circuit
modified to turn on and off a bulb instead of a LED.
It uses a 555 timer IC working as an astable multivibrator.
The flashing rate can be varied from very fast to a
maximum of once in 1.5 sec by varying the preset VR1.
The ON time of the circuit is given by: TON= 0.69xC1x(R1
+ VR1) second
and the OFF time is: TOFF=
0.69xC1xVR1 second
You can increase the value
of C1 to 100uF to get a slower flashing rate of upto
once in 10 sec.
