1 Hertz Clock Timer

Binary counters are based on powers of 2. So an 8 bit/flipflop counter can divide by 256 (2 to the power of 8) So you'd need at least a 26 bit counter to divide 32Khz down to a 15min on/off rate. The 4521 only has 24bits and the UA2240 has 8bits.

Thank you, I will order the Ics. once I get the ics, how would I hook them up????I t would be nice if you can post a layout.

You won't be able to get exactly 15min on/off with just those ICs. I'm not really familiar with the UA2240, I just skimmed the datasheet, so you may need something else instead. Hold off with ordering parts until a diagram appears.

O.K sounds good thank you.

Ok, I haven't done a diagram for you yet, but have a design in my head that may work assuming you can source the parts from your location. Digikey should have them. You would need:

32768hz crystal
CD4060B
CD4060B
CD40103B
10pf
39pf trimmer cap
15MΩ
330KΩ
Some 0.1uF decoupling caps.
Some sort of power supply, transistor, relay etc

Yes, you need 2 CD4060Bs.
The reason for two CD4060Bs is because of the odd divide ratio required. When you divide by N, and N is not a power of 2, you'll get a unsymmetrical waveform. The first CD4060B has the oscillator and divides it by 4096; the 40103 divides by 225; the 2nd CD4060B divides by 64 giving a symmetrical output.

He is gone

KMoffett said:

Ormo...are you still around?

Click to expand...

He moved to his next project while enjoying the long thread he started. Most likely, he has bought a clock.