This circuit was taken from old American documentation. The transistors used make it possible to control a motor with up to 2 A of current. They must be equipped with heat sinks.
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The circuit in the figure is based on an LM101A; diodes can be replaced with equivalents. The...
This circuit, with magnetic sensor, uses an operational amplifier of the time. The circuit is from...
Found in a 90s Popular Electronics, this circuit checks if a remote-control transmitter is...