From: phil_a@tpg.com.au   
      
   "John Lunatic Stewart"   
   >   
   >> ** All you need is a 3.5 digit DMM and a 2.2 ohm WW 5 watt resistor PLUS   
   >> a   
   >> regulated, adjustable voltage PSU capable of 1 amp DC. Connect the 2.2   
   >> ohm   
   >> resistor and winding in series and energise the pair with the bench PSU   
   >> -   
   >> set the voltage to about 2 volts.   
   >>   
   >> The ratio of voltages across the winding and the resistor will be the   
   >> same   
   >> as the ratio of their resistances.   
   >>   
   >> 5th grade math will suffice -  and a pocket calculator.   
   >   
   >>  ** Snip smartarse shite.   
   >   
   >   
   >> But thankyou Phil for your carefully considered response. You may go to   
   >> the head of the class now.   
      
     ** Been that for nearly all my school career.   
      
      
   >> Happy to note you are still on top of your game, whatever that might be.   
   >> And you have hit the nail squarely on the head as usual. Perhaps the   
   >> solution I offered was somewhat off track for RAT.   
      
   ** It's the method I regularly use for measuring the primary ohms of large   
   power transformers.   
      
   Not just at room temp, but also when they are at full operating temp too  -   
   cos the ratio of the two resistances allows the internal temp of the tranny   
   to be calculated with good accuracy.   
      
   The fractional increase in resistance is simply multiplied by 245 to get the   
   actual temp rise of the copper - which is the thing that matters most.   
      
   Eg:   
      
   The resistance increases by 25%  = 0.25   
      
   So the rise in temp is 245 x 0.25   = 61 degrees C   
      
      
   ...  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)