Breadboard of clock, timebase, and power supply

Time is now: 4:43

60Hz in to 1min out

So what's a person to do when he's got er 'time on his hands'?

No PIC or microprocessors, strictly CMOS counters and logic chips.

A 60hz tap is derived from the same transformer that provides the 9VDC power to this system. It was actually the most difficult thing to actually get working correctly. As it turns out, the CMOS inputs are Very Susceptible to Noise. I was buffering the 60Hz by a simple transistor, which was pulled high by a 10K resistor.

I found that I needed a 10K 'pull down' resistor for everything to clock nice and smooth. Once I fixed the timebase, the unit worked great.

The remainder of the circuit is composed of 4029 counters, 4514 and 4017 decoders and not much else.

The high-tech display is the just mounted on a coffe can. Someday I may actually build it 'for real'.