This power supply for model railroad was found in a February 1961 Radio Electronics Magazine. The transistor must be mounted on a heatsink and the transformer is a 1,5A secondary winding.
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...