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Multimeter specs - Strelok - 05-14-2020

Hello all,

I am in the market for a new multimeter, or how you call it nowadays.

Is True RMS useful for AC or is it just more expensive?
I'm thinking about a Voltcraft meter.

Kind regards,


RE: Multimeter specs - K O'Connor - 05-14-2020

Hi Strelok

A meter with "true RMS" readout is often deemed to be more accurate on all scales, although this may not be the case. Most meters read AC mains voltages pretty accurately but may have a limited frequency range with that accuracy. A true-RMS meter might have better accuracy reading audio signal levels, but you don't know unless a bandwidth for AC is given. Every meter will generally give a reading for audio signals that is fairly close to reality.

How much resolution you need depends on what you intend to test or are trying to measure AND whether you have other test equipment like an oscilloscope to show waveforms by other means. A scope shows the peak values, but modern ones sometimes have built-in metering that is displayed on-screen.

Have fun

RE: Multimeter specs - Strelok - 05-18-2020

Thanks for the elaborate answer!

You iz the thankee!

A meter without RMS sets me back 100 euros, for RMS they charge 30 euros extra... not worth it.

I also wanted to use it for the humble task of measuring outlet voltage.
That's because I may want to build the Symmetric Source, and I want to be sure about heater voltage before I order a Tx.

So the measuring ocurred. One pole gave me 5.3, the other one 103.
A bit low.
That could be 216 V? Also a strange value for Holland.

Kind regards,


RE: Multimeter specs - K O'Connor - 05-20-2020

Hi Erik-Jan

The Symmetric Source should only be a 1:1 PT with a CT on the secondary. This is easily achieved using a transformer with dual primaries and dual secondaries, OR a single primary with dual secondaries that add up to the mains.

For example:, in Europe you might have a single 240V primary but dual 120V secondaries. This will achieve the symmetric output.

Mains voltage is only read accurately from one pin to the other as LINE to NEUTRAL. A measurement from earth may show grounding problems but may not show the actual mains voltage.

Have fun

RE: Multimeter specs - Strelok - 05-22-2020

Hi Kevin!

Thanks again!
Yes, there's no heater thing going on in the SymSource.
But I wanted to know if I should buy a 220, 230 or 240 Tx, because that will infuence the heater voltage in the end.

Wow, I did not know that about mains AC, thanks for clearing that up!