The analog VOM most in use when I was an industrial electronics tech
was the Simpson 260. Its input impedance was 20K Ohms per volt on the
DC scales and 10K on the AC scales, as I recall. Later on, we went to
FET-input analog meters, for testing microcircuitry, which had an input
impedance nearing infinity (read waaay up there). These meters used
battery power for all scales, of cuss, as do the DMMs.
I agree about the test light. The way I found that the 1-2 lockout
switch on my new (to me) OD tranny was spotty was a combo of test light
and DMM. The DMM showed asome minimal resistance across the contacts,
but the 12v test light (a tail light lamp with some clip leads soldered
onto it) was noticably dimmer thru the switch. OTOH, one could have
discerned the same problem by reading the voltage drop across the
switch; IE: read the voltage to ground at the connection between the
switch and the solenoid and subtract the reading from the voltage at the
wire harness connection going to the switch. It's all in using the tool
correctly. (G)
CR
Paul Hunt wrote:
>
> Digital meters may present *less* of a load than analogue, but analogue
> voltmeters present a very low load when compared to car circuitry (as
> opposed to valve/tube radios and TVs, for example). A low load in car
> electrics is a *dis*advantage, not an advantage, since without a proper load
> a voltmeter will not show that you have bad connections in a circuit, which
> is why a test-lamp is usually better for testing go/no-go circuits like
> lamps, and the voltmeter for relative readings like the charging circuit.
>
> PaulH.
>
> ----- Original Message -----
> From: <Duinhoven_Hans@emc.com>
> To: <ccrobins@ktc.com>; <barrier@bconnex.net>
> Cc: <djw69@idt.net>; <mgs@autox.team.net>
> Sent: Sunday, June 11, 2000 9:27 PM
> Subject: RE: Multimeter
>
> > The standard AVOmeters are powered by the voltage or current which is
> > measured.
> > Only when measuring resistance power of battries is used.
> > Disadvantage of this is the meter makes a load for the measured voltage.
> >
> > Digital meters make a very small load = advantage.
> >
> > Cheers,
> >
> > Hans
> >
> > -----Original Message-----
> > From: Charley & Peggy Robinson [mailto:ccrobins@ktc.com]
> > Sent: zaterdag 10 juni 2000 18:21
> > To: Barrie Robinson
> > Cc: Dave Wood; MGB
> > Subject: Re: Multimeter
> >
> >
> >
> > Hay, ya gotta portable ohmmeter that doesn't rely on a battery? Neat
> > trick! (G) Where'dja get it.
> >
> > CR
> >
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