Precision wirewound pot wiper bounce?
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From: AM on 13 Jul 2010 17:42 On Wed, 14 Jul 2010 07:09:41 +1000, David Eather <eather(a)tpg.com.au> wrote: >On 14/07/2010 12:34 AM, oparr(a)hotmail.com wrote: >> Recently bought the 3-turn wirewound pot below to replace a worn 1- >> turn conductive plastic pot; >> >> http://media.digikey.com/photos/Vishay%20Spectrol%20Photos/533,534,535%20SERIES.jpg >> >> Out of the box, the thing exhibits wiper bounce or something similar. >> Every now and then the wiper appears to momentarily lose contact with >> the element while turning the knob. I would expect that with a worn >> pot but not a new one. Is this a bad pot or is this a caveat with >> wirewoud pots? >> >> Other new conductive plastic and cermet pots work just fine, however, >> can't get them in anything other than 1-turn. > >These are 3 turn conductive plastic - 10k and 5k > >http://australia.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6023740 > > >http://australia.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6023756 What is it, a small helix that the wiper climbs?
From: Grant on 13 Jul 2010 19:34 On Tue, 13 Jul 2010 14:42:08 -0700, AM <thisthatandtheother(a)beherenow.org> wrote: >On Wed, 14 Jul 2010 07:09:41 +1000, David Eather <eather(a)tpg.com.au> >wrote: > >>On 14/07/2010 12:34 AM, oparr(a)hotmail.com wrote: >>> Recently bought the 3-turn wirewound pot below to replace a worn 1- >>> turn conductive plastic pot; >>> >>> http://media.digikey.com/photos/Vishay%20Spectrol%20Photos/533,534,535%20SERIES.jpg >>> >>> Out of the box, the thing exhibits wiper bounce or something similar. >>> Every now and then the wiper appears to momentarily lose contact with >>> the element while turning the knob. I would expect that with a worn >>> pot but not a new one. Is this a bad pot or is this a caveat with >>> wirewoud pots? >>> >>> Other new conductive plastic and cermet pots work just fine, however, >>> can't get them in anything other than 1-turn. >> >>These are 3 turn conductive plastic - 10k and 5k >> >>http://australia.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6023740 >> >> >>http://australia.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6023756 > > > What is it, a small helix that the wiper climbs? Looks that way. Grant.
From: oparr on 13 Jul 2010 20:02 > These are 3 turn conductive plastic - 10k and 5k Thanks! That's good to know. Copal makes good stuff, I use their surface mount trimmers. Strange that Digikey, being a Copal distributor, doesn't carry those pots. On Jul 13, 5:09 pm, David Eather <eat...(a)tpg.com.au> wrote: >
From: ehsjr on 14 Jul 2010 00:39 oparr(a)hotmail.com wrote: >>We use a lot of the Bourns 3590 sereis ten turn pots. > > > I'm using the pot to vary the voltage to the VCO input of a function > generator. A 1-turn pot is a bit coarse and I estimate that a 10-turn > pot is going to be too fine. The 3-turn pot is just right except for > the mentioned issue. I'll try replacing that first. Thanks! > Can you add a cap to debounce it? Ed > > On Jul 13, 11:43 am, George Herold <gher...(a)teachspin.com> wrote: >
From: oparr on 14 Jul 2010 08:19
> Can you add a cap to debounce it? Actually, that's the first thing I tried. Unfortunately, any cap value that showed signs of improvement would cause an unwanted lag between pot setting and frequency. On Jul 14, 12:39 am, ehsjr <eh...(a)nospamverizon.net> wrote: > |