Test circuit with bridge (CB22530E)

This bridge-biased transistor test circuit measures gain in the range 0 to 300. Circuit is from Radio Electronics June 1952.

Wireless battery charger (CB7267E)
The idea of this 1982 Experimenters Handbook circuit is to generate an RF signal in L2 that can be...
Digital Speedometer (CB16759E)
This circuit was found in a 1994 documentation, but it can be easily assembled today, as it uses...
Coded Lock with Alarm (CB17377E)
We found this circuit in a year 2000 documentation. It must be powered by a voltage of 5 V as it...