you need
  • voltmeter, multimeter, an ammeter
Determine Whether you measure AC or DC voltage .Switch avometr or multimeter to DC or AC.Most often, there is a need to measure the voltage power source or electromotive force (EMF).If even approximate the parameters of the data voltages are not known, the initial stage of the measurement device should be included in the measurement mode of maximum stress.Connect the device according to the polarity.
After the first measurement, if the readings are too small, the measurement mode, you can change to decrease the voltage.The data are EMF voltage m developing on the power supply terminals, but are not voltage m working circuit, because it does not take into account the load.
In order to measure the voltage at the load, connect to the source of the current consumed by the device.Turn on the power and carry out the measurement, the results of which will not EMF, and operating voltage .
To measure voltage on elements of the working device, testers, voltmeters and multimeters are not suitable, because of the low self-input impedance of the circuit introduce strong distortions in the measurement and the failure mode of the test device.For such measurements, it is recommended the special equipment - tube voltmeter or similar devices FET having a high input impedance.These devices can measure voltage tube and transistor devices even while they work.