This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
We found this circuit in an old Mullard (Philips) documentation. The sensor consists of a...
This simple circuit, powered by 4 batteries or 9 V battery, brings together several functions of...
This circuit was found in an American documentation from 1977. The mechanical resonator or ceramic...