This circuit for photography uses was found in the Electronics Experimenter Handbook Special projects magazine from 1983. The bargraph circuit powers 8 LEDs.
This circuit from the 80's makes use of two transconductance operationals of the time. Modern...
This circuit was obtained in a documentation from the National Bureau of Standards of 1968. The...
In the figure we have a diagram of a thermostat using an NTC and an operational amplifier 741. The...