Musical Christmas Lights - Rebuild 90' Circuit

Thread Starter


Joined Nov 14, 2021
Hi! I want to rebuild a 90's music box with the following specifications, like the original one I had:
- 220v supply voltage
- 8 songs, exactly the ones on UM3481A
- two light outputs (strings), 2x50 bulbs

The original assembly used a COB memory with two basic outputs:
1. The sound for the buzzer;
2. A square wave light signal was sent to the Clock input pin of a JK Flip-Flop, respectively GD4027B (/ CD4027B) to alternate the two light outputs during song playback.

Given that the IC UM3481A has exactly the same songs, I wondered if I could use the ENV (Envelope Circuit Terminal) output as the Clock input for the JK Flip-Flop.