3-tube receiver (T1602E)

Found in a 1949 Radio Electronics, this circuit employs vacuum tubes of the time. Power supply not provided.

Hearing Aid Amplifier (CB6286E)
Suggested by Amperex in a 1968 documentation, this circuit is based on TAA370, an integrated circuit...
Adapter for Multimeter (CB1360E )
If you have a common analog multimeter, you can increase its input resistance in the measurement of...
VHF and UHF switch with diodes (CB9227E)
This simple circuit for switching RF signals was found in an RF Design from the 90s. The circuit...