This game was found in an old Popular Electronics. The unijunction transistor can be 2N2646. The supply can be done with voltages from 6 to 12 V.
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...