Found in old American documentation, this receiver receives modulated infrared signals and converts them into sound. The audio amplifier circuit can be replaced by a modern equivalent.
This oscillator uses a general-purpose transistor that can have BC548, BF494 or 2N2222 equivalents and...
Offset Adjustment on an Amplifier with the LM139 (CB14245E) In the figure we have the way of...
The critical components of this 1978 circuit are transformers, which, hopefully, can be obtained from...