Transistor Voltmeters (TVMs)

Transistor Voltmeters (TVMs) Points : Transistor Voltmeters (TVMs) Before the transistor Voltmeter (TVMs) the Vacuum tube Voltmeters (VTMs) were in use. Due to the following advantages over VTVMs) the transistor voltmeters (VTMs) are preferred.

1. A TVM does not require any warm up time while for a VTVM a warm up time is necessary in order to obtain drift free indications.
2. A TVM is comparatively compact and is light is weight and thus well suited for field work.
3. A TVM may be designed as a battery operate instrument. For field work, an instrument, whose power supply is an internal batter, is necessary. Thus a battery powered TVM is a very popular choice for use in locations where a source of external power is not available. Also for measurements in an area that contains trouble some ground loops, a battery powered instrument is to be preferred over a mains powered voltmeter to remove the ground paths.
4. A conventional transistor offers a low input resistance as compared to Vacuum tube.