Inside a wirewound pot
in [Design]
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From: m II on 16 Jul 2010 01:44 Nummy, Yummy, NewBunnyDroppings wrote: > First off, you dope... nobody suggested a damned thing about YOUR > pot. This one's for YOU, Archi....in celebration of your MOUTH. A twisted old Pervo named BART! Liked to inhale his own Fart "It goes down like a dream, The gas makes me scream, And the beans are good for the heart!" mike
From: Lostgallifreyan on 16 Jul 2010 03:23 m II <c(a)in.the.hat> wrote in news:4c3ff1b2$1(a)news.x-privat.org: > Nummy, Yummy, NewBunnyDroppings wrote: > >> First off, you dope... nobody suggested a damned thing about YOUR >> pot. > > This one's for YOU, Archi....in celebration of your MOUTH. > Yeah, nunya usual numpties here, that one's special. >:) Oh I am so punny today.
From: oparr on 16 Jul 2010 07:45 > First off, you dope... nobody suggested a damned thing about YOUR > pot. More comic relief. Not as amusing as "screwface Allison" but along the same lines. What are these guys using to fry their brains. On Jul 16, 12:12 am, Nunya <jack_sheph...(a)cox.net> wrote: >
From: oparr on 16 Jul 2010 10:47 > IIRC those pots are constructed with fine wire wrapped around an > insulating rod that forms the major helix. Take a closer look with > a magnifying glass at your wire to see if this is what you have. You're probably right. I'll take a macro shot later. Interesting design.....The pot resistance with wipers installed is 10K. It's 33K without the wipers. All indications are that this is a 10-turn 33K pot with only one wiper/ carrier installed. With two wipers it can be made to be < 10-turn with resistance < 33K depending where the wipers are placed (always equidistant from the ends). I can see clearly now. The sharp lower values in the scope shots are due to the high wiper losing contact with the element leaving only the low wiper. Occassionaly, I saw positive going spikes/steps but couldn't figure out how that could happen if a single wiper lost contact with the element. Apparently, positive spikes/steps result when the low side wiper loses contact with the element leaving only the high. > Turning the knob slowly should allow the > wiper to drop between 2 turns, bridging them, and give you a step > response. If the winding cannot be seen by the naked eye then the wiper is probably shorting several turns, by design, at any given time based on the relative size of the wiper. > Rapid turning can cause wiper bounce. Actually, rapid turning back and forth cured the problem. That has always been my experience with WW pots. Probably oxide or crud buildup on the wire IMO. Trying to find a more proactive solution. On Jul 15, 10:41 pm, "Artemus" <bo...(a)invalid.org> wrote: >
From: oparr on 16 Jul 2010 13:47
> IIRC those pots are constructed with fine wire wrapped around an > insulating rod that forms the major helix. Yes, you're right; http://www.pbase.com/eldata/image/126570664 > Turning the knob slowly should allow the > wiper to drop between 2 turns, bridging them, and give you a step > response. Maybe; http://www.pbase.com/eldata/image/126570665 Provided the step you are referring to is not what is shown in the scope shots. Again, the real issue occurs when the wiper makes no contact at all which seems to be either due to oxidation or crud on/ between turns. Lots of crud in those two close ups. On Jul 15, 10:41 pm, "Artemus" <bo...(a)invalid.org> wrote: > |