Anyone have the Heathkit GC-1108 clock? It is a bit more rare than the earlier ones.
I'd like to find out the procedure for changing the displayed time from the 24 hour wiring to 12 hour wiring.
YES, I have the Heathkit GC-1108 clock. This clock kit sold for $27.95 in 1990.
I found my Heathkit assembly manual over the holidays.
You MUST remove the 24-HOUR wiring (jumpers) before proceeding to the 12-HOUR wiring steps.4 resistors and 2 diodes are required for 12-hour operation.===
Pages 14 and 15 of GC-1108 Assembly Manual
NOTE: You can wire the alarm clock to display in a 12-hour or 24-hour format.
If you prefer the 12-hour format refer to the
12-Hour Wiring. Refer to
24-Hour Wiring, if you prefer a 24-hour display format.
Refer to PICTORIAL 2-2 for the following steps.
12-HOUR WIRING (Part A)- R11: 1200 ohm resistor
- R14: 10 Kohm resistor
- D6: 1N4148 diode
- R4: 10 ohm resistor
- Install a 3/8" jumper wire at holes N and O.
- R10: 220 ohm resistor
- Install a 3/16" jumper wire at holes AA and AB.
NOTE: You will have to reform this wire to fit the hole spacing.- Install a 3/16" jumper wire at holes Y and Z.
NOTE: You will have to reform this wire to fit the hole spacing.- D7: 1N4148 diode
- Solder the leads to the foil and cut off the excess lead lengths.
This completes the "12-Hour Wiring"24-HOUR WIRING (Part B)- Connect a 3/8" jumper wire at holes V and WW.
- Connect a 3/8" jumper wire at holes T and U.
- Connect a 3/8" jumper wire at holes R and S.
- Connect a 3/8" jumper wire at holes X and Z.
NOTE: You will have to reform this wire to fit the hole spacing.- Solder the wires to the foil and cut off the excess wire lengths.
This completes the "24-Hour Wiring"