It serves as a reference, since today we can have simpler and more compact solutions. This circuit is from an Electronics Experimenter Handbook from 1992. The integrated circuits are from that time.
Suggested by Motorola documentation from the 1980s, this circuit makes use of MOSFETs of the time....
In the figure we have a small general-purpose amplifier with the LM386 integrated circuit and...
This circuit allows you to use a digital multimeter as a thermometer. The sensor is mounted in a...