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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This balance control for the channels of a stereo system was found in a 1969 Mullard...
The article that teaches the assembly is from a Radio Electronics issue from July 1969. The...
Found in old English documentation, this circuit is still current. The circuit trips with a sound...