[sdiy] 9mm plastic knob and metal spline shaft pots from Song Huei in Tiawan

[Robin Whittle]

Further to the thread "Re: [sdiy] ALPS RK09K 9mm "knob shaft" pots", I
received some samples from Song Huei in Tiawan:

  http://www.song-huei.com.tw

Here is what I wrote to them.  I have five of both types of pots and can
mail one or two to someone if they are interested.

I am using the metal shaft Tiawan Alpha pots such as:


http://www.jaycar.com.au/productView.asp?ID=RP8504&form=CAT2&SUBCATID=968#1

in my TR-808 modifications: http://www.firstpr.com.au/rwi/tr-808/

They are fine for this, though I would like them better if they turned
more freely.  None of these knob functions require great precision -
that would be required if they were tuning VCOs.

   - Robin



  R0903N-B10K, L-20KQ

    http://www.song-huei.com.tw/product.php?mode=list&cid=79

    I am comparing these with ALPS pots which I currently use, such as
    the RK09K1130-K20-C0-A103.  I much prefer the ALPS pots because they
    are relatively easy to turn.  Your pots are stiffer, and this may
    be preferred by some people.

    Also, there are three things I prefer about the ALPS pot.  (I sent
    them this photo:


http://www.firstpr.com.au/temp/sdiy/Song-Huei-and-ALPS-9mm-plastic-shaft-knob-type.jpg


      1 - The ALPS pots are more comfortable to touch since there is a
          full conical chamfer.  The Song Huei pots have the spline
          edges of the side of the knob sharply protruding instead of
          following the conical chamfer of the rest of the knob.

      2 - The ALPS pots have a substantial indicator marking on the
          top of the knob, whereas the Song Huei indicator line does
          not go much further to the centre than the edge of the
          conical chamfer.

      3 - The ALPS pot has an evenly molded top of the knob, while
          the Song Huei knob has a circular molding mark.


  RK0971-B10K,L-20KC/CI/N=7

    http://www.song-huei.com.tw/product.php?mode=list&cid=11


    These have a similar stiffness to the Tiawan Alpha pots I am
    using at present.  Ideally I would like pots which turn more
    freely, such as the BI Technologies P091N-QC25BR5K, which I
    bought from Mouser.com.

    I can obtain the Tiawan Alpha pots in the small quantities I
    currently need, in Australia from a retailer called Jaycar.
    The BI Technologies pots are not available anywhere like this
    except for a few values at Mouse.  If I had a project which
    required larger quantities, I could order some BI Technology pots.

    However, there is a more serious problem with the Song Huei pots:
    there is a lot of backlash between the shaft and the wiper.  This
    means the shaft has to be turned somewhat back and forth before
    it moves the wiper in the opposite direction to the one it has
    just been turned in.  The Tiawan Alpha pots have this problem too,
    but it is my impression that the Song Huei pots are worse.

    I have only tried one or two BI pots, but I think they have little
    backlash.  In any application which involved precision, as some of
    my future projects would, I would only choose the BI Technology
    pots.  As far as I know, ALPS do not make pots like these.

    My present application is relatively low volume and does not require
    great precision.  So the Tiawan Alpha pots are OK.

    One advantage of your pots is that the threaded shaft is longer
    than that of the Tiawan Alpha and BI pots.  In my current
    application I had to make a special countersunk drilling
    arrangements so I could use the Tiawan Alpha pots.  This would
    not have been necessary if I was using your pots.