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 circuit for an anti-theft radar that operates at 400 MHz in a Radio Electronics from...
In the figure we have a diagram of a thermostat using an NTC and an operational amplifier 741. The...
This version of a call-fish is from 1981 using, for this reason, a 90 V battery that is no longer...