This circuit was found in a Popular Electronics from the 90s. It is intended to power the filament of old radio valves in recovery works. It is indicated for tubes that use 5 V of filament.
This small transmitter with 2 transistors can reach several hundred meters using a 30 to 70 cm...
This 1969 circuit generates a high voltage that reaches 100 V from 16 V. The power is of the order...
This shield circuit, from a documentation from the 70s, employs an optocoupler with two SCRs to...