This simple tester was found in a Popular Electronics from the 90s. The circuit is powered by two 9 V batteries since it requires a symmetrical source.
This circuit was obtained from a Poptronics in June 2001. The magazine no longer exists, but the...
We find this circuit in a 1980s documentation. The circuit uses uncommon components today which can...
This circuit has a very high input impedance and a very low output impedance. We found it on a...