Auto power off circuit.

[mariah1902]

I want to make a device which will help me to auto power off my ac supply so that I can turn on my motor and select a desired time and make that motor stop after that time is over. So basically either it can be controlled by a stop watch or a real clock. So what do I need and how much can it cost?. I want to make it with a small cost a I want it to deliver to each and every person in my area who are suffering from water wasting problem.

 

[d123]

Hi,

Maybe a microcontroller and a relay plus a few other components. A timer plug is a ready-made solution if the motor has a plug.

'Really simple' could be a CD4060 or similar, or even a 555 monostable if great timing accuracy isn't important, set to turn on when you turn the motor on, or start a timed on-period with a pushbutton plus a latch like a flip-flop one, to keep the counter high and use the lowest frequency pulse needed to unlatch a relay, and turn off the latch at the same time.

 

[stenzer]

Hi,

it highly depends on the desired accuracy and set time. What are your design goals?

BR

 

[dr pepper]

Presumably accuracy is not that important.
You could use a pnuematic timer, you can get them in the form of a light switch, push it and it slowly returns switching off after a period of time, and the timer element doesnt need any power.