Mark Burnley
Well-known member
Jaakko,
Before you get bogged down in wiring multiple JK flip-flops, have a look at this schem:
...it's from one of the Elektor books. It uses the CMOS 4028 BCD-to-decimal decoder IC. So each input is effectively 1, 2, 4 and 8 decimally-speaking. You then take the outputs from the 1, 2, 4 and 8 pins respectively. The diode-feedback path forms a latch, which causes the output to hold until the next input select. The ULN2803 IC is a good relay driver, as it has the bac-EMF protection diodes built in.
I know this is only 4 inputs, but with a bit of diode-matrix fun, you could add extra outputs. Gotta go out now, but I'll discuss this later...
Mark
Before you get bogged down in wiring multiple JK flip-flops, have a look at this schem:
...it's from one of the Elektor books. It uses the CMOS 4028 BCD-to-decimal decoder IC. So each input is effectively 1, 2, 4 and 8 decimally-speaking. You then take the outputs from the 1, 2, 4 and 8 pins respectively. The diode-feedback path forms a latch, which causes the output to hold until the next input select. The ULN2803 IC is a good relay driver, as it has the bac-EMF protection diodes built in.
I know this is only 4 inputs, but with a bit of diode-matrix fun, you could add extra outputs. Gotta go out now, but I'll discuss this later...
Mark