In this interesting circuit from Popular Electronics, the output voltage is the square root of the input voltage. Equivalent operational amplifiers can be tried out.
This 1987 signal injector included the power supply from the power grid. The transformer is 6 + 6...
This amplifier was found in a 70s documentation. The product gain x bandwidth is 350 MHz. The...
This simple receiver with junction FET uses a high impedance magnetic earphone (over 2 k). Power...