This circuit triggers a relay when a light beam that hits the phototransistor is cut off. The circuit is from Electronics Now and the supply voltage depends on the relay voltage.
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...