From: apogosso@tpg.com.au   
      
   "Phil Allison"  wrote in message   
   news:97pt5bFb2pU1@mid.individual.net...   
   >   
   > "Alex Pogossov"   
   >   
   >>   
   >> In any case, an abrupt interruption of the plate current will cause a   
   >> voltage spike on the OPT primary. The stored magnetisation energy of   
   >> Lp*(Ia^2)/2 will have to be dissipated. Lp can be quite high in a decent   
   >> amp. If a load is connected, then the energy will be dissipated in the   
   >> load giving you a loud crack in the speaker. A residual smaller energy   
   >> stored in the leakage inductance Ls*(Ia^2)/2 will most likely be safely   
   >> dissipated in a snubber of say 2200pF+5K usually connected in parallel to   
   >> the OPT primary.   
   >>   
   >> But what is the load is not connected? Then the huge magnetisation energy   
   >   
   >   
   > ** Why huge ???   
   >   
   > If Lp is say 100H and  Ia = 0.1A  then how many Joules is that ?   
      
   Apparently 0.5J.   
      
   It is the same as charging a 10uF to 315V or 47uF to 160V. If you are in   
   Europe or Australia, try charging 10uF from the grid through a diode and   
   then discharging it with a screwdriver... The closer you keep the cap to   
   your face when discharging -- the better... Then you will see if it is huge   
   or not... It is all subjective after all... If you are in the US, use 47uF   
   for a similar experiment.   
      
   Enjoy   
      
   Alex   
      
   --- SoupGate-Win32 v1.05   
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