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[canadianpoet2012]

My new project is to build an LED clock with 7-segment displays. I have a ring of 12 LEDs to signify the hour, and two 7-segments to show the minutes, with pulsing LEDs to indicate the seconds.

My problem is this: I need to make a counter that will count up to 59 for me (0 to 59) so that I can count a minute. If I can get a 555 to produce second pulses, then I can use this counter to control my minute decade counter. This in turn can control my second minute decade counter, and with the aid of a NAND gate, these two combined will control my two hour decade counters.

Can anyone advice me how to make a counter to count off 60 seconds? I don't really know where to begin, except with a 555 circuit giving off second pulses. Any advice would be much appreciated!

 

[jbeng]

If you want to use 4000 series CMOS, you could use a 4518 dual BCD counter. Use one of the counters in the package to count 0-9 seconds. Set up the other to count tens of seconds, having the counter reset itself to zero (by adding an AND gate) when it reaches "6". You can get the 4518BE from Digi-Key for less than $0.50US ea. You could use another 4518 to count your minutes.
Also, while a 555 can be used for great many things, if you use it for a 1-second timebase in this app, you'll probably find yourself spending a lot of time resetting your clock to keep the time correct. IMHO, a better way (although a bit more expensive) would be to use a crystal oscillator and divide the frequency down to get your 1-second timebase signal. For instance, use a 1MHz crystal oscillator and divide it with a string of 4518's ... you'll only need 3!
Hope this helps... JB