Rheostats & Potentiometers

Discussion in 'General Electronics Chat' started by PackratKing, Jul 30, 2015.

  1. PackratKing

    Thread Starter Well-Known Member

    Jul 13, 2008
    Rheostat 1.jpg rheostat 2.jpg Some time ago, the Packrat snagged some older electronic gear from the local recycler... long story

    Among the " treasures " were a few larger {ruler} Clarostat pots, or wirewound rheostats may be more accurate. Being the eternal Novice, I was searching google for old Claro units, to little avail.

    I opened one up gingerly, and noted the wirewound resistance element, and wondered if anyone might know the wattage of something like this...

    This is much larger than some of the 2 watt units with a carbon element in my rat collection, ... so I was thinking at least 5 watts ?? the numbers on the can... top to bottom...11-36, 7.5K ohm, 140-6831

    What say Y'all ??
  2. #12


    Nov 30, 2010
    Here is a 2 watt Clairostat, so I think you're about right at 4 to 5 watts.
    Funny thing, they aren't rated as high as you might imagine from the size because the cooling capabilities were worse back then. Cast a jaundiced eye.
  3. strantor

    AAC Fanatic!

    Oct 3, 2010
    Here's a 50w ohmite, circa 1993. It's only half an inch wider than yours. But it's open in the rear, for cooling I suppose. 20150730_195548.jpg
    PackratKing likes this.
  4. PackratKing

    Thread Starter Well-Known Member

    Jul 13, 2008
    Hi Strantor...
    I have a few of these... although used, they appear in good shape... I have been toying with designs to build these using fire-clay, epoxy, and NiChrome windings... coil spacing remains a stumbling block, prior to final coating of epoxy insulation...

    Will likely use "Corona Dope " for insulation, tho I need to hi-pot materials to know which will stand the stress...
    Last edited: Jul 31, 2015