This circuit is from Motorola documentation, but can be implemented with virtually any phototransistor and any general-purpose transistor. The supply voltage can also be changed.
This is the receiver for the previous circuit. The audio amplifier supports equivalents. The...
This filter is from 1978 documentation. The source must be symmetrical and the gain in the center of...
Found in July 1975, Radio Electronics magazine this circuit can use any operating circuit,...