This test circuit was found in the PE Hobbyst Handbook in a 1990s edition. The circuit tests the battery under load. The load, as the battery is selected by the switch.
This General Electric circuit is from the 80's. The PUTs used in this meter are not common...
This circuit provides a power of the order of 2 W, characterized by high performance. The output...
The sensor can be made using two bare wire or two screen with a piece of tisse between them. One...