RE: [TCML] Meters (was Variac)

["Lau, Gary" <Gary.Lau@xxxxxx>]

I changed the Subject to "Meters", as that's what this is really about.

Voltmeters are not at all aware of or rated for the load current, or power.  It doesn't matter to them, they're not even capable of sensing that.  I'm not sure in what context the eBay unit you mentioned was for use "in the ma level".  It's possible that this was the load current that the _meter_ draws, unrelated to how much your Variac load (coil) draws, but this is usually insignificant and a don't-care.

Similarly, a current meter is unaware of and doesn't care what voltage the power supply is providing.

Only in a Wattmeter, a 4-terminal device, is power (the product of both voltage and current) relevant.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of jhowson4@xxxxxxxxxxx
> Sent: Friday, October 24, 2008 11:31 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Variac
>
> Sweet thanks for the help.  I guess my question is really how do I determin how
> much power such a meter would be able to handle.  all the web sites i found just list
> what voltage its good for and not what current or power.
>
> Like if if got a regular old volt meter 0-150 AC what current could I use it with.  the
> one i was going to get on ebay i found out from the seller to be rated for 150v but
> only in the ma level.  well thats no good for my TC variac.
>
> I do like what you said about the  ""circular" transformer" thing .  Is that like a toroid
> core type set up.
> anyone try to make one of these before.
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