This was an off the shelf “Billy Bass” singing fish, that I re-programmed to sing one of our original songs.
It was more of a challenge than I originally thought, because you have to sync up the mouth movements with the vocal track, so I couldn’t just simply replace the audio.
My solution was to gut the electronics in the fish, install a stereo mp3 player circuit, and an audio activated switch to control the mouth. I used one channel of audio for the actual music, and on the other channel I recorded audio pulses when I wanted the mouth to move. The audio activated switch would then trigger the mouth motor every time it heard that pulse.
To make the head swing out, I had to cheat because I only had one control channel. So I just made another audio controlled switch, but used a large capacitor to increase the pulse time to around one second. This circuit was connected to the same audio track, and as long as their were mouth trigger pulses, it would keep the head trigger active until one second after the last mouth trigger.