Re: Newbie Circuit Design Help

Ed,
So if we nixed the display - can this be done off the shelf?

Justin


EdV wrote:
cjdublu wrote:
I need help designing a timing circuit.

The circuit should not use a PIC, and an IC is preferable.

The circuit needs to countdown from 180 minutes to zero.

Intended use:
A start button to begin counting
A red Led lit while counting
At the end of the 180 minutes the red Led should go off, green led on
Hit a reset to turn all leds off
Circuit sits idle until start pressed again.

I also need the "countdown" displayed on 3 seven segment leds.

Any help appreciated!

Thanks,
Justin

1. The count down 7 segment LEDs is the simplicity killer here. It is
not going to be a one or two IC solution. I know you don't want to use
a Pic but using the kit at Radio Shack for $79 and three hours of time
and you would be 25% of the way to making this circuit work.

2. If you don't want to use the Pic go to Radio Shack anyway and pick
up Volume I: Timer, Op Amp, and Optoelectronic Circuits & Projects by
Forrest Mims.

3. Or just keep googling. Buy one of these and reverse engineer it:

http://www.hobbytron.com/UK247.html

Good luck,
Ed V.

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