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 small general purpose and RF transistor tester appeared in a February 1958 Radio Electronics...
The MC4741 integrated circuit consists of four operational amplifiers similar to the 741 in a...
We found this touch control on a Popular Electronics from 1970. The circuit makes use of an...