Autocutoff and restore

[Pitamber Kaushik]

I need (edit) an analog circuit that upon switching on, after a few seconds, deactivates for a constant time (of the order of few hours), during which subsequent presses don't turn on my load (an LED). After the passage of that duration of a few hours, the circuit again becomes active for a single press and so on. Please help.

 

[Nigel Goodwin]

Use a micro-controller, and program it to do the job - it will require very few components, and fairly simple software.

 

[Pitamber Kaushik]

Thanks. I was eyeing an Analog Circuit. The time duration is too high for Capacitors to be practical. Is there some other way?

 

[Nigel Goodwin]

Thanks. I was eyeing an Analog Circuit. The time duration is too high for Capacitors to be practical. Is there some other way?

There's always 'another way', but it will be much more complicated, much more expensive, and probably much less accurate.

One 8 pin PIC, an odd resistor and capacitor, and that's the lot for a micro-controller.

 

[crutschow]

The easiest approach for such a long period, other than a uc, is to use a CD4060 counter/oscillator, such as shown here.

 

[Nigel Goodwin]

The easiest approach for such a long period, other than a uc, is to use a CD4060 counter/oscillator, such as shown here.

Which is still pretty inaccurate as it uses a crude free running oscillator, and considerably more parts than a PIC version would - where the internal oscillator would be many times more accurate, even though it's not a crystal.