The indicator for this circuit is a 0 to 1 mA milliammeter. The operational is from the 70s, when the circuit was published. Modern equivalent can be used.
We found this circuit in a 1967 Japanese technical magazine. The transistors are made of germanium at...
This two-transistor radio was found in a Japanese publication from the 1960s, with no information on the...
The purpose of this circuit is used in communications and to respond to signals that are in the 2...