The true voltage is found as follows:
no warm-up is necessary. It is a portable, versatile
meter that is free of calibration errors caused by aging
82 - 22
tubes or line voltage variations.
22 × 10 - 1
The VOM does have two disadvantages:
1. The VOM can load the circuit under test.
2. The meter movement is easy to damage
E = 117.7 volts
because of improper testing procedures.
During troubleshooting, you will often measure
switches, jacks, and additional devices arranged in a
voltage, current, and resistance. Rather than using
compact, portable case. It uses one meter movement.
three or more separate meters for these
measurements, you can use the multimeter. The
mechanism responds only to direct current. To adapt
multimeter contains circuitry that allows it to be a
this mechanism for measuring alternating current
and voltages, a rectifier or thermal converter must be
multimeter is often called a volt-ohm-milliammeter
One advantage of a VOM is that no external
power source is necessary for its operation. Therefore,
Figure 2-4.--Schematic diagram of a typical multimeter.