28 V to 5 V converter (CB7331E)

Found in National Semiconductor documentation from the 90's, this circuit has an output current of 5 V. The integrated circuit must have a heat sink.

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Telephone dialer (CB21268E)
This circuit was found in Electronics Now. With it the dialing signals of a telephone are...
Dual-intensity LED (CB22128E)
This circuit switches the brightness of the LED. We found it in an English documentation....
Simple metal detector (CB7960E)
This circuit already explored in several diagrams in this section was found in a 90’s Popular...