Forums

Trimpot with decent rotational life?

Started by Phil Hobbs May 9, 2017
On Thursday, May 11, 2017 at 3:57:39 AM UTC-4, Spehro Pefhany wrote:
> On Wed, 10 May 2017 16:40:05 -0700 (PDT), the renowned George Herold > <gherold@teachspin.com> wrote: > > >We use a lot of those too. 1" diameter hole for pot=20 > >(trim off plastic tabs on pot) > >and ~1/4" hole centered (somewhere) on the 1" circumference=20 > >for the solder tabs. > > Next time get slots! Way stronger and easier to solder. > > https://i.imgur.com/4DWYbKz.png > > --sp > > -- > Best regards, > Spehro Pefhany
Hi Spehro, not sure what that is. (Maybe I'm misunderstanding.) I meant this, https://www.dropbox.com/s/hir1owa5sjpeb4q/DSCN9663.JPG?dl=0 Which looks like a used a 3/8" hole on the perimeter. George H.
On Thu, 11 May 2017 08:24:11 -0700 (PDT), the renowned George Herold
<gherold@teachspin.com> wrote:

>On Thursday, May 11, 2017 at 3:57:39 AM UTC-4, Spehro Pefhany wrote: >> On Wed, 10 May 2017 16:40:05 -0700 (PDT), the renowned George Herold >> <gherold@teachspin.com> wrote: >> >> >We use a lot of those too. 1" diameter hole for pot=20 >> >(trim off plastic tabs on pot) >> >and ~1/4" hole centered (somewhere) on the 1" circumference=20 >> >for the solder tabs. >> >> Next time get slots! Way stronger and easier to solder. >> >> https://i.imgur.com/4DWYbKz.png >> >> --sp >> >> -- >> Best regards, >> Spehro Pefhany > >Hi Spehro, not sure what that is. (Maybe I'm misunderstanding.) >I meant this, > >https://www.dropbox.com/s/hir1owa5sjpeb4q/DSCN9663.JPG?dl=0 > >Which looks like a used a 3/8" hole on the perimeter. > >George H.
Ah, I thought you were putting a board onto the pot to make connections to it. Pretty common technique in some quarters- a little transition board with a connector. --sp -- Best regards, Spehro Pefhany
On Thu, 11 May 2017 18:52:08 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Thu, 11 May 2017 08:24:11 -0700 (PDT), the renowned George Herold ><gherold@teachspin.com> wrote: > >>On Thursday, May 11, 2017 at 3:57:39 AM UTC-4, Spehro Pefhany wrote: >>> On Wed, 10 May 2017 16:40:05 -0700 (PDT), the renowned George Herold >>> <gherold@teachspin.com> wrote: >>> >>> >We use a lot of those too. 1" diameter hole for pot=20 >>> >(trim off plastic tabs on pot) >>> >and ~1/4" hole centered (somewhere) on the 1" circumference=20 >>> >for the solder tabs. >>> >>> Next time get slots! Way stronger and easier to solder. >>> >>> https://i.imgur.com/4DWYbKz.png >>> >>> --sp >>> >>> -- >>> Best regards, >>> Spehro Pefhany >> >>Hi Spehro, not sure what that is. (Maybe I'm misunderstanding.) >>I meant this, >> >>https://www.dropbox.com/s/hir1owa5sjpeb4q/DSCN9663.JPG?dl=0 >> >>Which looks like a used a 3/8" hole on the perimeter. >> >>George H. > >Ah, I thought you were putting a board onto the pot to make >connections to it. Pretty common technique in some quarters- a little >transition board with a connector. > >--sp
Here's an encoder mounted on a baby board. https://dl.dropboxusercontent.com/u/53724080/PCBs/Encoder_Board.jpg The four spacers are also the electrical connections. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Thursday, May 11, 2017 at 6:52:03 PM UTC-4, Spehro Pefhany wrote:
> On Thu, 11 May 2017 08:24:11 -0700 (PDT), the renowned George Herold > <gherold@teachspin.com> wrote: > > >On Thursday, May 11, 2017 at 3:57:39 AM UTC-4, Spehro Pefhany wrote: > >> On Wed, 10 May 2017 16:40:05 -0700 (PDT), the renowned George Herold > >> <gherold@teachspin.com> wrote: > >> > >> >We use a lot of those too. 1" diameter hole for pot=20 > >> >(trim off plastic tabs on pot) > >> >and ~1/4" hole centered (somewhere) on the 1" circumference=20 > >> >for the solder tabs. > >> > >> Next time get slots! Way stronger and easier to solder. > >> > >> https://i.imgur.com/4DWYbKz.png > >> > >> --sp > >> > >> -- > >> Best regards, > >> Spehro Pefhany > > > >Hi Spehro, not sure what that is. (Maybe I'm misunderstanding.) > >I meant this, > > > >https://www.dropbox.com/s/hir1owa5sjpeb4q/DSCN9663.JPG?dl=0 > > > >Which looks like a used a 3/8" hole on the perimeter. > > > >George H. > > Ah, I thought you were putting a board onto the pot to make > connections to it. Pretty common technique in some quarters- a little > transition board with a connector.
Oh well maybe, I thought Phil was sticking a big ass pot through a pcb. Doesn't matter. I'm mostly an idiot when it comes to mechanical layout. On my first instrument, (for money rather than one-of's in labs.) I used those pots at right angles from front panel to pcb, but didn't mechanically secure the alignment enough... (Forget shake machines, just mail packages to yourself via UPS.) When ~50% (or so.) were broken on arrival we had to change things. George H.
> > --sp > > -- > Best regards, > Spehro Pefhany
On 09/05/2017 22:20, Phil Hobbs wrote:
> Trouble is, all the trim pots I can find are ~200 cycles rated > rotational life, or not rated at all. >
If you think their skills are adequate you could use through hole trimpots in TO-5 sockets or whatever suitable socket you find and a bag of spare trimpots with instructions on how to swap trimpots when worn! piglet
<snip>

> > DPOTS are slow, too. Trimpots are usable at a GHz or so.
Hmmm, for pots I recall a thumb rule of f x R < 1E6... I would have thought that perhaps a small, low R trimpot might be usable at 100MHz. Did you really got them working as expected at 1 GHz? Pere
On Fri, 12 May 2017 11:23:10 +0200, o pere o <me@somewhere.net> wrote:

><snip> > >> >> DPOTS are slow, too. Trimpots are usable at a GHz or so. > >Hmmm, for pots I recall a thumb rule of f x R < 1E6... I would have >thought that perhaps a small, low R trimpot might be usable at 100MHz. >Did you really got them working as expected at 1 GHz? > >Pere
Yes, we've tested trimpots up there. Most pots have a convoluted geometry inside, that adds capacitance and inductance. Some tiny pots are more sensible. This Bourns pot has the convoluted geometry https://dl.dropboxusercontent.com/u/53724080/Parts/Resistors/Bourns_Pot_2.jpg and this 7-cent Murata part https://dl.dropboxusercontent.com/u/53724080/Parts/Resistors/Tiny_Pot.JPG doesn't. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com