This watch uses a liquid crystal display. The circuit is from the 80s and the module used is uncommon nowadays. Power is provided by a single cell.
We found this high gain circuit with the LM381 preamplifier in a Radio Electronics from February 1990....
We can produce pulses controlled through this circuit that can function as a shield if powered by a...
If mounted with SMD components, this transmitter will be so small that it can be installed inside a...