I played with some Chinese scales. Didn't trust the 1.2v flea squeak signal to carry so I put pcb's on the back and buffered then to 5v.

I built hardware interface that did 3 scales and interrupted the processor whenever a full report was in and read it as 3 bytes from the shift registers.

They had 3 counts of jitter which was inconvenient if you didn't want to dump the bottom 2 bits altogether. The battery positive connected to the rule which was not exactly convenient, dragging a ground wire across the metal they were connected to sent them haywire so I had to try and insulate them from the machine with Tufnol. Was getting on pretty good then one of them switched to 5 counts of jitter and I rather gave up.