You searched for: “vr tube
voltage-regulator tube, voltage regulator tube, VR tube
1. A glow-discharge tube that maintains an essentially constant tube voltage drop over the operating range of current.
2. A glow-discharge tube in which the tube voltage drop is approximately constant over the operating range of current.

It is used to maintain an essentially constant direct voltage in a circuit despite changes in line voltage or load.

This entry is located in the following unit: volt + (page 7)