1-Ttube reflex receiver (T1555E)

This one-tube circuit is equivalent to the previous one. We find it in a 1924 book by Gernsback, Power is made by batteries.

Wide Band Oscillator (CB4932E)
The frequency of this oscillator can be set in a range from 5000 to 1. We found it in an old...
Liquid Level Detector (CB19922E)
This circuit is used to detect the water level in a reservoir. It triggers the charge when the...
Binary Test (CB17400E)