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
- 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.