Wattmeter (T1351E)

This circuit is from a February 1949 Radio Electronics magazine. The circuit uses 3 tubes and includes the power supply.

Speed Alarm (CB3988E)
We found this circuit in an old Mullard (Philips) documentation. The sensor consists of a...
Injector and Signal Follower with Continuity Tester (CB18713E)
This simple circuit, powered by 4 batteries or 9 V battery, brings together several functions of...
Mechanical resonator filter (CB7517E)
This circuit was found in an American documentation from 1977. The mechanical resonator or ceramic...