This converter for the 150 MHz band was found in an American documentation. Transistors are uncommon today and equivalents can be used.
This circuit is from a 1957 Raytheon transistor manual. The diode can be of general-purpose...
Found in a Popular Electronics from the 80's, this bridge allows the measurement of resistances in 5...
Direct current motors from 5 to 12 volts and currents up to 2A can be controlled with this...