High Power Alarm (CB20475E)

We found this circuit in a Popular Electronics from the 90's. The circuit uses three SCRs to trigger the loads.

Improved Baxandall (CB13692E)
We found this circuit in a 1974 technical documentation. The circuit can be made with BC549...
Precision Analog Gate (CB13220E)
The operational amplifier of this configuration from the 70s is the 741 in its Motorola version from...
Simple Transistor Test (CB17139E)
This circuit is used to test PNP or NPN transistors giving the status indication through LEDs. The...