[volt-nuts] Precision resistors

[Laurence Motteram]

"Wattage" and precision resistors could make for a very long thread.  For best stability, you do not want to heat up the resistor very much.  A power rating would normally be related to a permitted temperature rise, but you might not want your resistor to rise to that temperature.  This way leads to several interrelated compromises.

Laurence Motteram

________________________________________
From: volt-nuts-bounces at febo.com [volt-nuts-bounces at febo.com] on behalf of Joseph Gray [jgray at zianet.com]
Sent: Sunday, 18 August 2013 2:47 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Precision resistors

Raj and John,

Thanks for the advice. I'll go with some mild dish detergent and water. The
black, rectangular resistors are definitely marked "Daven", just like all
the others.

The bobbins are marked .02%, 1/2 W. The black rectangles are .1% (no
wattage) and the micas are simply marked 85, which I assume is the
resistance. Any idea what the wattage of the black ones are? Also, what
percentage and wattage would the micas be? The micas are thumb-sized
squares (just so I don't confuse the metric or imperial users :-) ).

Joe Gray
W5JG



On Sat, Aug 17, 2013 at 7:18 AM, J. Forster <jfor at quikus.com> wrote:

> The red 'sealant' is Glyptal laquer. Probably safe to water wash.
>
> I would not use any solvent on the bobbins.
>
> The black encapsulates are likely Vishay, if they look like CK-05/6
> ceramic caps. Alcohol should be safe for a quick rinse.
>
> -John
>
> =============
>
>
>
> > Nothing abrasive should be used. Soap and water and old toothbrush is
> what
> > I would try. Very high values avoid water!
> > I use a cheap ultrasonic clear for some things in the shack!
> >
> > Raj
> > VU2ZAP
> > (former resistor manufacturer)
> >
> > At 17-08-2013, you wrote:
> >>What is the recommended method for cleaning dirt, oil, etc from precision
> >>resistors? I'm talking about a combination of wirewound on plastic
> >> bobbins,
> >>wirewound on mica (and sealed with something) and an unknown type that is
> >>encapsulated in black plastic rectangles. These are all 1950-1960 vintage
> >>and are marked "Daven".
> >>
> >>Joe Gray
> >>W5JG
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