Here is a simple example how to build cool looking binary 24 hour clock. Red LEDs shows seconds, green LEDs minutes and yellow LEDs hours.
Case contains four buttons to adjust the time. Clock works with 9 volts.
This clock is easy to do and parts cost only few bucks, so it is also cheap to do.
Step 1: Schematic and Parts
I used the blue colored case, because it was cheap and looked good to my eyes.
- Clock crystal (Q1) 32.768 kHz.
I think the easiest way to get that crystal is take it from the old wall clock.
- 560pF, 22pF capacitors and one 10M resistor
- 1 x 4060 IC, which is the 14bit ripple counter.
With 32.768 KHz clock crystal this IC gives 2Hz out from the pin number 3
- 3 x 4024 IC
This is 7bit ripple counter
- 2 x 4082 IC
Dual 4-input AND gate
- 1 x 2,1mm plugin
- 17 x led
Red, yellow, green or what ever you like
- 17 x 470 Ohm resistors
I used the 9 Volt supply, so the output from the pins is something around 9V. Typical forward
voltage for these LEDs are about 2 Volts. Let's want that, the current to the LED is something about
0,015 A = 15 mA, then (9-2)V / 0,015A = 466 Ohm -> 470 Ohm is size of resistors.
Now it's time to download 4020 14-stage ripple counter data sheet and we will find that, the
max output current is 4mA =), but it is enough and works anyway.