[sdiy] 2 multimeters showing different voltages

[Scott Gravenhorst]

"Scott" <Scott at scottwick.com> wrote:
>I've got two multimeters, and each is showing a different voltage.  One
>shows my synth to be at a solid 15 volts, and the other shows it at
>17.5.  
>
>I tested my computer PSU to try to figure out which one is correct, and
>I still don't know!  One shows the PSU 12v output at 11.05, and the
>other shows it at 12.62.
>
>Both meters are less than 3 years old, and have little use.  One is a
>radio shack, the other is a Velleman.  
>I'm starting to think that the one that shows 17.5v (and 12.6 on the
>computer PSU) is correct.  However, that would mean my synth PSU came
>calibrated incorrectly.  (which is possible.. its just a used power-one
>supply)
>Does anyone know how I can figure out which to trust?  
>
>Also, how much of a difference would those 2 volts make?  If my synth
>PSU is putting out +/- 17.5v, would that explain some tuning issues I've
>been having?


I've used new fresh batteries as a reference to test meters.  I don't say that you
should calibrate against batteries, but as a quick go-no-go test, hook two new fresh
9 volt batteries in series.  This should display 18 volts on a reasonably accurate
meter.  (note that 18 volts is very close to the 17.5 volt reading you are seeing on
one meter).



-- ScottG

-------------------------------------------------------------

-- Scott Gravenhorst
-- GateMan I - Xilinx Spartan-3E Based MIDI Synthesizer
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