[sdiy] 1/8" shaft pot comparison: Honeywell/Clarostat vs. Vishay & Bourns

[GRAHAM ATKINS]

Hi Robin,

Vishay have recently bought up many component manufacturers into their
"Group". They are generally known in the trade for precision and  
quality so
I would expect them to be OK. Also, the fact that they have bought  
Spectrol
for example does not necessarily imply that the products are made at a
different location rather than the Spectrol factory, it is merely a  
name change.

Graham

On Sep 8, 2008, at 7:21, Robin Whittle wrote:

> Thomas White's recent message about Vishay (who took over Spectrol)
> pots prompted me to write this comparison.
>
> What used to be "Spectrol" pots are now made by Vishay, and I think
> the white Vishay 148 (conductive plastic) (and I guess the 149
> cermet) pots are horrible.
>
> They in no way resemble a Spectrol 148 (black plastic, made in
> Mexico) pot which I recently bought from Farnell.  That would be old
> stock - and my impression of it is very positive.  The old Spectrol
> 148 has a nice feel and is not to stiff.
>
> The Vishay 148s I got are bad in these respects:
>
>  1 - Very stiff, with a rough kind of stiffness and considerable
>      stiction.
>
>  2 - Have (I guess) a few degrees of slop between the shaft and the
>      wiper actually moving.
>
>  3 - A bump in the friction at each end of the travel, due to the
>      wiper riding up on the raised surface of the conductive
>      material where it overlays the metal contact layer.
>
> Also, internally, there is just a metal-to-metal pressure contact
> between the pins and the resistance element - not a rivet, solder or
> conductive epoxy.
>
>
> Vishay 248 pots are not available in log AFAIK.
>
>
> Vishay P9 pots are smaller and I recall they are too stiff - mine is
> pulled apart now.
>
>
> I bought some Bourns 51/53.  I thought they were OK, but too stiff.
>
>
> I am very happy with the Honeywell 308 series, such as the 308N10K
> from Digikey.  These are fresh production (0826 date code on the box
> and 0710 on the pots) from Mexico and arrive in a Clarostat box.
>
> They are light and very smooth, apart from a barely perceptible bump
> at each end.  These pots are begging to be tweaked!
>
> Internally I think they are very well constructed, with proper
> joints, no slop, grease throughout the wiper area as well as the
> rest of the pot.
>
>
> BI Technologies have recently gone into production with 1/8" shaft
> conductive plastic pots: P260/261.
>
> This is most promising, since I was concerned these would be hard to
> get in the future.
>
>  http://www.bitechnologies.com/pdfs/p260.pdf
>
> I asked for some samples via their web form, but nothing happened.
>
> BI Technologies claim a lifetime of a million cycles, while the pots
> mentioned above generally have a spec of 50,000 cycles.  This
> doesn't mean the pot would stop working after 50k cycles - just that
> its resistance behavior might not meet the original specifications.
>
> - Robin
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