This circuit was found in a 1967 RCA documentation. The components are of the time. The circuit limits the current to 50 mA when the battery is fully charged.
This low-power intercom can be powered by solar cells. The circuit is two-way, with an integrated of the...
Reversing the switching action, with the output going high when the input is low, can be done by...
This converter was found in the June 1991 issue of Radio Electronics magazine. The circuit uses...