But i would need a pulse time of about 2 mins and a pause time of about 12 hours. can this be done by altering the resistors, if so, how do i find out what values they need to be replaced with?
Im not after 2 hours of cycle, just 2 mins. And i would need it to turn on every 12 hours.
One guys said this in a review:
I used this timer to cycle a small 12v water pump for six hours a day last summer. I built another similar device for this summer and so far this new timer is working flawlessly.
There are several ways, you could use a microcontroler or build an oscillator that generates a pulse every two miniutes and connect it up to a divide by 360 counter (use a >9-bit counter with a reset on 360) and connect the output to an array of gates so it goes high at 0001.
You can buy small digital timers that plug into the wall, this will allow you to program when a device is turned on an off to the nearest miniute during a 24 hour period.
Why do you want to do this?
I assume you want to turn something on for two miniutes every 12 hours.