i want to make a bulb on and off at intervals of say half an hour. readymade timers available in shops(india) costs much and does not support shorter intervals like half an hour. any cheaper electronic circuit which can do this control? from where can i get the circuit or its diagram?
Depending on your skills, a CMOS 555 timer chip could probably drive a solid state switch (triac) for this interval although a more reliable timing, especially if you want exactly a 50% duty cycle, by feeding the timer output into a counter, so that the 555 cycles say 32 times (once a minute about) for each change of state of the selected output. Smaller cycle times are more stable.
