To design&build an analogue study timer

Please how do i go about designing and building an analogue study timer. How do i go about it and what do i need to do this.The timer should be able to time any activity for at least 3 hours.Also,is there a possibility for an alarm?

Analogue timer

3 hours is a bit long for an analogue timer. Does it have to be analogue?

I assume you want to be able to press a button to start ther timer and have an alarm sound when it expires. Is this so?

An analogue design is possible, but a digital solution would be better.

I could design either for you if you wish. Just tell me your requirements.

Len

analogue timer

As ljcox pointed out digital would be probably easier. The 555 timer IC is a good choice, but for long periods the leakage of the timing capacitor prevents the time from being accurate and consistant repeatable times.
It is possible to set the timer as a astable oscillator at a higher frequency, followed by one or two cmos binary counters like the 4040 or 4060 and use gating to stop the count and turn on an alarm.
I too would be glad to help with a design

Re: Analogue timer

ljcox said:

3 hours is a bit long for an analogue timer. Does it have to be analogue?

I assume you want to be able to press a button to start ther timer and have an alarm sound when it expires. Is this so?

An analogue design is possible, but a digital solution would be better.

I could design either for you if you wish. Just tell me your requirements.

Len

Click to expand...

Yes.It should be analogue.It should have a button to start the timer and it should have an alarm.Thank you so much Len.I am expecting your reply.
-Charity.

Analogue timer

Circuit attached