At the present the possible sources of current for conductivity measurements are limited to the induction coil, the high frequency generator and the Vreeland oscillator. In the first two the oscillating current is produced mechanically and the noise from the mechanism is apt to interfere with the accurate balancing of the bridge when measuring the resistance of the conductivity cell. This may not be the greatest objection in the case of the induction coil as it has been shown that the current has an undirectional value. The Vreeland oscillator is the only apparatus in use which produces a tunable oscillating current by means of a rectifier and controlled by the capacity of the condenser and the inductance of the coils in the circuit. This circuit gives an oscillating current whose intergal value is zero, and there are no overtones or mechanical noise to interfere with accurate work.
Proceedings of the Iowa Academy of Science
©1920 Iowa Academy of Science, Inc.
Geaque, H. A. and Ralston, F. Paul
"Vacuum Tube Circuits as a Source of Power for Conductivity Measurements,"
Proceedings of the Iowa Academy of Science, 27(1), 199-201.
Available at: https://scholarworks.uni.edu/pias/vol27/iss1/28