digital multimeter

[Maine Sail]

Originally Posted by GordMay

Of Acoustic’s 5 DVMs, I see a (left - right) a Wea, Sperry Mastech, & Extech - but no Fluke.

For those wishing a quick tutorial on understanding specifications for DVMs, see the Fluke download:

Understanding specifications for precision multimeters:

http://support.fluke.com/calibration...00_ENG_A_W.PDF

My dad has my Fluke he needed it for some repair work to a gauge on his antique 356 speedster. When I took this photo I remembered he's had it for about a year.

I guess it's pay back for all the tools I "borrowed" when I was a kid.. What come around goes around! Now he's borrowing and not returning tools to me... BTW the Sperry and Mastech are usually in the closest agreement with the Fluke but I don't really trust any of them out past the hundredths.

From L to R UEI, Sperry, Mastech, Etek

[Maine Sail]

Originally Posted by amytom

(clamps only work on AC as with DC there is no collapsing magnetic feild to measure)

Clamps do work on DC amps but you need a DC capable meter. I have used my Mastech MS 2108 literally hundreds of times to measure DC amps.

Mastech MS 2108 (LINK)

[amytom]

Originally Posted by Acoustic

Clamps do work on DC amps but you need a DC capable meter. I have used my Mastech MS 2108 literally hundreds of times to measure DC amps.

How does it work? Only two ways I can think of, neither could be very accurate. Measure inrush current as the load is applied, or apply pulses to the clamp coil and measure the changes effected by the static feild around the DC conductor. The second would vary greatly based on angle of the coil to the conductor.

What method am I not thinking of?

[GordMay]

DC Clamp Ammeters utilize the Hall Effect & Lorentz Force to accurately measure Direct Current .

[amytom]

God I'm getting old!!! I'm loosing my touch. Thank goodness you can specialize at the systems level! Last time I studied Hall effect I was only using it for timing or proximity sensors; never thought about calibrating for current readings. Then again my first radar was an analog tube model, and my first quality meter was a Simpson 260.

Thanks again Gord for educating me.

[Cowboy Sailer]

Good grief Gord! I was going to tell about the Hall Effect but you beat me to it. You replied about an hour after Amytom posted. Do you have some sort of alarm? Like this, "NOW HEAR THIS, NEW POST ON FORUM!" When do you sleep?

[GordMay]

I generally sleep 9:00PM (0200 Zulu) through 3:00 AM EST (0800 Z)