The word "some" is not in what I said, only in your brain.
I don't need to read them; I wrote them.
You're the one who is always criticizing others for not paying attention to the context.
I was first descirbing moving iron ammeters, which read true RMS, then I told the OP that "You can also get moving iron voltmeters which will (also) read true RMS (just as moving iron ammeters do). The entire context is about moving iron meters and the parentheticals are implied by the context. If you didn't understand it, you're not paying attention to the context.
I said "You can also get moving iron voltmeters which will read true RMS."
I could have said "You can also get moving iron voltmeters (some of) which will read true RMS."
Or, I could have said "You can also get moving iron voltmeters (a few of) which will read true RMS."
Or, I could have said "You can also get moving iron voltmeters (most of) which will read true RMS."
Or, I could have said "You can also get moving iron voltmeters (all of) which will read true RMS."
I didn't bother to use the last locution because the convention in English is to take a missing quantifier to be the universal quantifier "all". If you want to take it to be something else, you certainly may, but don't attribute an error to me because of your choice.
Please read my reply to Phil for more information. This CT circuit with silicon diodes is not very linear and it may not even show any current below about 1 ampere. It should be much better if you use germanium diodes or Schottkys. You may also consider using something like an old small audio output transformer with a 4 ohm secondary used for current, and the primary may have enough turns to drive a bridge rectifier.
That is the standard connection for rectifier type AC current meters, and I did not think it needed to be stated. But this is a basics newsgroup and I should have been more specific. When I worked as a meter technician I assembled and calibrated many meters which contained a small CT and copper oxide rectifier directly to the meter movement, or with a small resistor to provide adjustment and damping.
A CT with a bridge rectifier on its output very quickly generates enough voltage to overcome the forward drop of two diodes. For a 500:1 ratio CT, the primary voltage only needs to be about 3 mV. It also depends on the VA rating of the CT (in this case about 2 VA), and the coupling of the primary winding to the core and the core to the secondary, and the magnetic characteristics of the core. These are complex and not well defined, as you stated.
Yes, but the OP wanted to read AC current from a variable transformer and most likely without any DC component. A search for an iron vane AC amps panel meter turned up this one, from Simpson, distributed by Grainger, for about $90:
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Iron vane meters tend to be fairly rare and expensive, as well as being bulky and possibly not as rugged as most DC meters with a D'Arsonval movement. Here are some cheap AC panel meters. They might be iron vane or rectifier type:
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The following information about Yogogawa meters states that iron-vane
*voltmeters* may exhibit inaccuracy of as much as 75% at the extremes of rated frequency from 20 to 400 Hz, so the frequency effect is quite significant. But for iron vane *ammeters*, the frequency effect is very small:
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The specs for Triplett iron vane meters indicate an effect of 1% over the range of 25-133 Hz.
** Fraid that is something not seen everyday in electronics.
** Shows just what a total f****it you are.
** It is a basic *electronics* NG !!
You should never allude to things outside the realm of electronics as if they are inside it.
** Not an electronics job.
It is related to electrical engineering.
** Bully for you.
** Massive false assumption !!!!!!!!!
The load presented to a variac can be almost anything, including half wave rectified which may be deliberate of the result of faulty equipment. A faulty bridge in a SMPS, a faulty triac in a lamp dimmer etc.
** You can pick nice ones up on Ebay for low prices.
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