Ilmhéadar digiteach le haghaidh tomhas voltais
Ceann de na feidhmeanna is bunúsaí atá ag DMM ná voltas a thomhas. De ghnáth is é tástáil an voltais an chéad chéim chun fadhb ciorcaid a réiteach. Mura bhfuil aon voltas ann nó má tá an voltas ró-íseal nó ró-ard, is é an chéad rud atá le déanamh ná an fhadhb cumhachta a shocrú sula ndéantar seiceáil breise.
The waveform of the AC voltage may be sinusoidal (sine wave) or non-sinusoidal (sawtooth, square, etc.). Many DMMs can display the "rms" (effective value) of AC voltage. The rms value is the value at which the AC voltage is equivalent to the DC voltage.
Many tables have an "average responding" function, which gives valid values when a pure sine wave is input. Such meters cannot accurately measure the rms value of non-sinusoidal waves. DMMs with true-rms function (true-rms) can accurately measure the true-rms value of non-sinusoidal waves.
Tá cumas DMM voltas AC a thomhas teoranta ag minicíocht an chomhartha atá á thomhas. Is féidir leis an gcuid is mó de DMManna voltais AC a thomhas go cruinn ó 50 Hz go 500 Hz. Mar sin féin, is féidir le bandaleithead tomhais AC an DMM na céadta kilohertz a bhaint amach. Maidir le voltas AC agus reatha, ba cheart go mbeadh an raon minicíochta comhsheasmhach le sonraíocht DMM.
