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From: DrParnassus on
On Tue, 22 Jun 2010 18:50:38 -0700, John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>On Tue, 22 Jun 2010 17:59:40 -0700, John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Tue, 22 Jun 2010 16:54:15 -0700, DrParnassus
>><DrParnassus(a)hereforlongtime.org> wrote:
>>
>>>On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje
>>><pNaonStpealmtje(a)yahoo.com> wrote:
>>>
>>>>Got 10 resistors on tape marked 2M7.
>>>>Used one, circuit did not work right.
>>>>Took some testing ... before I measured the resistors.
>>>>Of the 10 several are 620 k and not 2M7.
>>>>Bought from www.voti.nl, so beware.
>>>>All are marked with the right color code for 2M7.
>>>>
>>>>New to me :-)
>>>
>>> A normal handheld DVM barely measures 1MOhm correctly so anything up
>>>there and over will not likely be easily measured with cheap handhelds.
>>
>>
>>AlwaysWrong!
>>AlwaysWrong!
>>AlwaysWrong!
>>
>>1.1 meg and 4.7 meg, 5% resistors read...
>>
>>Fluke 8845A benchtop 1.08220 M 4.6390 M
>>
>>Fluke 87 handheld 1.083 M 4.64 M
>>
>>Fluke 75 handheld 1.084 M 4.66 M
>>
>>
>>The last two haven't been calibrated in years.
>>
>>The biggest problem is the terrible TC of the carbon film resistors.
>>
>>I'll try a cheap Extech when I get home.
>>
>>AlwaysWrong!
>>AlwaysWrong!
>>AlwaysWrong!
>>
>>
>>John
>>
>
>Extech model 26: 1.088, 4.68. It's pretty cold, been soaking in the
>garage for a year or so. It's a pretty nice meter, for a cheapie: it
>does t/c temperature, capacitance, frequency, duty cycle.
>
>Oh, did I mention that you're AlwaysWrong?
>

7.5Mohm/V? Hahahahaha what a cheap meter! My old analog meter was
20MOhm per volt input impedance.

And you actually think that the CLAIMED 1.2% accuracy claim of
resistance readings applies at the fringes of the scale? Sure, bub. At
40M Ohm, 'coffee breath' changes the reading.

A 40M Ohm scale?

Hahahahahahaha... Sure, bub. You would not even be able to zero the
meter and the basic Ohms test circuitry is too low in voltage to test
values that high.

Even then accurate readings can only be counted on if the meter is
permanently mounted in a 'breeze free', humidity controlled box and the
reading be taken from within with all those values logged for each
reading.

Outside the box, one could acquire a reading that can be between 7 and
12 percent off the mark on the bottom of range values and even worse than
that as resistance goes up toward the top of the range..
From: John Larkin on
On Tue, 22 Jun 2010 20:23:11 -0700, DrParnassus
<DrParnassus(a)hereforlongtime.org> wrote:

>On Tue, 22 Jun 2010 18:50:38 -0700, John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Tue, 22 Jun 2010 17:59:40 -0700, John Larkin
>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>>
>>>On Tue, 22 Jun 2010 16:54:15 -0700, DrParnassus
>>><DrParnassus(a)hereforlongtime.org> wrote:
>>>
>>>>On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje
>>>><pNaonStpealmtje(a)yahoo.com> wrote:
>>>>
>>>>>Got 10 resistors on tape marked 2M7.
>>>>>Used one, circuit did not work right.
>>>>>Took some testing ... before I measured the resistors.
>>>>>Of the 10 several are 620 k and not 2M7.
>>>>>Bought from www.voti.nl, so beware.
>>>>>All are marked with the right color code for 2M7.
>>>>>
>>>>>New to me :-)
>>>>
>>>> A normal handheld DVM barely measures 1MOhm correctly so anything up
>>>>there and over will not likely be easily measured with cheap handhelds.
>>>
>>>
>>>AlwaysWrong!
>>>AlwaysWrong!
>>>AlwaysWrong!
>>>
>>>1.1 meg and 4.7 meg, 5% resistors read...
>>>
>>>Fluke 8845A benchtop 1.08220 M 4.6390 M
>>>
>>>Fluke 87 handheld 1.083 M 4.64 M
>>>
>>>Fluke 75 handheld 1.084 M 4.66 M
>>>
>>>
>>>The last two haven't been calibrated in years.
>>>
>>>The biggest problem is the terrible TC of the carbon film resistors.
>>>
>>>I'll try a cheap Extech when I get home.
>>>
>>>AlwaysWrong!
>>>AlwaysWrong!
>>>AlwaysWrong!
>>>
>>>
>>>John
>>>
>>
>>Extech model 26: 1.088, 4.68. It's pretty cold, been soaking in the
>>garage for a year or so. It's a pretty nice meter, for a cheapie: it
>>does t/c temperature, capacitance, frequency, duty cycle.
>>
>>Oh, did I mention that you're AlwaysWrong?
>>
>
> 7.5Mohm/V? Hahahahaha what a cheap meter! My old analog meter was
>20MOhm per volt input impedance.

It was probably 20K ohms per volt. "Ohms per volt" applied to
non-amplified VOMs, and that's - with a 50 uA meter movement - about
as good as they ever got.

Wrong, again.

>
> And you actually think that the CLAIMED 1.2% accuracy claim of
>resistance readings applies at the fringes of the scale? Sure, bub. At
>40M Ohm, 'coffee breath' changes the reading.
>
> A 40M Ohm scale?
>
>Hahahahahahaha... Sure, bub. You would not even be able to zero the
>meter and the basic Ohms test circuitry is too low in voltage to test
>values that high.

You still seem to be thinking in terms of old fashioned VOMs. How old
are you anyhow?

The Extech measured the 1M and 5M resistors just fine.

>
> Even then accurate readings can only be counted on if the meter is
>permanently mounted in a 'breeze free', humidity controlled box and the
>reading be taken from within with all those values logged for each
>reading.

Ludicrous. I don't start to need shielding until 1G ohms or so.

>
> Outside the box, one could acquire a reading that can be between 7 and
>12 percent off the mark on the bottom of range values and even worse than
>that as resistance goes up toward the top of the range..

It's hilarious that you claim to have worked with high voltage power
supplies.

John

From: Robert Baer on
Jan Panteltje wrote:
> Got 10 resistors on tape marked 2M7.
> Used one, circuit did not work right.
> Took some testing ... before I measured the resistors.
> Of the 10 several are 620 k and not 2M7.
> Bought from www.voti.nl, so beware.
> All are marked with the right color code for 2M7.
>
> New to me :-)
If the resistors are bad, then tame them using a whip!
From: Robert Baer on
John Larkin wrote:
> On Tue, 22 Jun 2010 16:54:15 -0700, DrParnassus
> <DrParnassus(a)hereforlongtime.org> wrote:
>
>> On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje
>> <pNaonStpealmtje(a)yahoo.com> wrote:
>>
>>> Got 10 resistors on tape marked 2M7.
>>> Used one, circuit did not work right.
>>> Took some testing ... before I measured the resistors.
>>> Of the 10 several are 620 k and not 2M7.
>>> Bought from www.voti.nl, so beware.
>>> All are marked with the right color code for 2M7.
>>>
>>> New to me :-)
>> A normal handheld DVM barely measures 1MOhm correctly so anything up
>> there and over will not likely be easily measured with cheap handhelds.
>
>
> AlwaysWrong!
> AlwaysWrong!
> AlwaysWrong!
>
> 1.1 meg and 4.7 meg, 5% resistors read...
>
> Fluke 8845A benchtop 1.08220 M 4.6390 M
>
> Fluke 87 handheld 1.083 M 4.64 M
>
> Fluke 75 handheld 1.084 M 4.66 M
>
>
> The last two haven't been calibrated in years.
>
> The biggest problem is the terrible TC of the carbon film resistors.
>
> I'll try a cheap Extech when I get home.
>
> AlwaysWrong!
> AlwaysWrong!
> AlwaysWrong!
>
>
> John
>
>
I bet the Extech will correlate rather well with the Flukes; i have
one and it reads within 0.2% worst case for all (valid) values except
when the value is less than a few hundred ohms where contact resistance
becomes part of the reading.
From: Phil Allison on

"Jan Panteltje"
> Got 10 resistors on tape marked 2M7.
> Used one, circuit did not work right.
> Took some testing ... before I measured the resistors.
> Of the 10 several are 620 k and not 2M7.
> Bought from www.voti.nl, so beware.
> All are marked with the right color code for 2M7.
>
> New to me :-)


** Though pretty rare, I have come across wrongly marked resistors in a
piece of commercial equipment !!

Dozens of resistors colour coded as 3.3kohms were in fact 4.7 kohms.

The correct value WAS 4.7 kohms - so the equipment maker knew about the
wrong coding !!


..... Phil


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