This circuit was found in a 1967 Electronics World. We can design it with a BF245 for the FET and a BC558 for the bipolar transistor. The circuit has 3 scales and a 10 M ohm input resistance.
This triac circuit was found in the July 1995 Electronics Now magazine. The triac is based on the...
We found this circuit in a 90s Electronic Design. The circuit is based on a quadruple operational...
The transistor may be any general purpose, but the integrated transistor is not common today....