From: dhky@shaw.ca   
      
   On 06/09/2013 1:55 PM, Salmon Egg wrote:   
   > In article , Don Kelly    
   > wrote:   
   >   
   >> On 04/09/2013 2:30 PM, Salmon Egg wrote:   
   >>> In article ,   
   >>>    "Paul Hovnanian P.E."  wrote:   
   >>>   
   >   
   >>    
   >>> It is more than that. Free wheeling rectifier combinations such as   
   >>> bridges, allow more efficient charging of capacitors by efficiency while   
   >>> the capacitor has almost no charge. Diodes still dissipate some power.   
   >>> Remember, repetitive charging and discharge from a non-inductive dc   
   >>> source delivers V*I/2 while drawing power V*I. V is peak capacitor   
   >>> voltage while I is the average (dc) current.   
   >>>   
   >>> My sarcastic point is that sudden changes in current in a conductor   
   >>> gives large voltages should be learned very early by anyone working with   
   >>> electrical circuits. I found that out early in life using dry cells and   
   >>> my mother's motorized mixer.   
   >>>   
   >> I also learned  that by fooling around with a 6V  dry cell and an old   
   >> Ford ignition coil (the kind in a nice wooden box- ). It takes skill (or   
   >>    ignorance) to hold a wire in each hand and energize the primary but   
   >> still get said hands across the secondary.   
   >   
   > It does not take all that much skill to get a shock because you do not   
   > need to touch the secondary at all. I am not all that familiar with   
   > modern ignition systems, but when points were in vogue, all you had to   
   > do was pry apart closed points with your fingers to find out just how   
   > high primary voltage could go. After all, preventing point contact spark   
   > prevention was why a capacitor was used.   
   >   
   > At one AIEE lecture I attended on the subject of electrical shock, I got   
   > an idea of how stupid a person can be. The lecturer said that someone   
   > wanted to see what kind of shock could be obtained from a 22.5V battery.   
   > He wet his hands with salt water before grasping wires to the battery.   
   > He managed to kill himself.   
   >   
   > Ordinarily, the lecturer said, that death from dc came because of   
   > inductive kick (ventricular fibrillation) or just getting cooked.   
   >   
   > At one time, I was using a photoflash battery (510V I think) to power a   
   > phototube. It was unpleasant to get across it but not truly terrible.   
   > Very occasional shocks like that didid not deter me from soldering to   
   > the battery's c contacts.   
   >   
   I think that you and Tom are right. My recollection of just where my   
   hands were (other than one was on each lead from the battery) are nearly   
   70 years old.  At that time it was just a box, obviously with electrical   
   parts and I had a 12V battery and no knowledge of di/dt   
   --   
   Don Kelly   
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