Found in a 303 Circuits from the 90's this circuit can use the lowest current range of a common multimeter. The circuit can measure currents as low as 100 pA.
This crystal or galena radio uses a germanium diode. C1 is an old radio variable and L1 has 100...
Other series amplifiers such as the MC3301, MC3401 and LM2900 can be used on this circuit. We...
Found in a 90’s American publication, this circuit has a voltage gain close to 1, as shown in the...