countdown timer

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Bob Haller
Posts: 24
Joined: Tue Oct 01, 2002 1:01 am
Location: pittsburgh pa

countdown timer

Post by Bob Haller » Sat Nov 15, 2003 6:10 am

As part of my game building activities I am looking for a countdown clock. Some sort of circuit or device that could be set for a short period of time say 60 seconds and countdown to zero. perhaps using LEDs or small light bulbs.
Any ideas and thanks for the help.

Posts: 563
Joined: Thu Dec 06, 2001 1:01 am
Location: New Hampshire

Re: countdown timer

Post by russlk » Sat Nov 15, 2003 4:50 pm

How about a 555 timer driving a 74xx192 BCD decade counter which drives a 74xx45 1-of-10 decoder? The '192 counts up or down and can be preset. If you cascade two '192s and set the timer for 1 second pulses, it can count up to 100 seconds. The Radio Shack LED bargraph display can be the indicator (276-081). I can draw a schematic if you need it.

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