This circuit can make use of almost any operational amplifier and the diodes are for general use. It is intended to excite an analog instrument.
This circuit is from a technical publication on voltage regulators from 1977. The transistor can...
This analog frequency meter for low frequencies was found in Radio Electronics magazine from July...
This circuit is from the 1983 Intersil Databook. The circuit operates on a 9 V battery and has a...