Re: Microwave Oven Caps

["Tom Stathes" <newphreak_16-at-yahoo-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Malcolm Watts"
> <M.J.Watts-at-massey.ac.nz> 
> 
> Hi Tom,
> 
> On 24 Jul 00, at 19:07, Tesla list wrote:
> 
> > Original poster: "Tom Stathes"
> <newphreak_16-at-yahoo-dot-com> 
> > 
> > Hello,
> >  In a series capacitor circuit the total voltage
> is
> > the sum of the voltages of all the caps.  The
> > capacitance can not be higher than the smallest
> cap. 
> 
> Right so far.
> 
> > In a paralell circuit the voltage can not be
> higher
> > than the highest voltage, but the capacitence is
> the
> > sum of all the caps.  Its just like connecting
> > batteries or transformers in series and paralell. 
> 
> Not quite. The working voltage of paralleled
> capacitors is 
> that of the *lowest* rated capacitor - if you
> parallel a 300V 
> cap with a 150V cap, the maximum working voltage is
> 150V.

I Know, that was a typo i did mean to say smallest.

>  
> > If i were to wire up all the caps in a box, and
> reopen
> > the oil fillhole case of each cap, then fill the
> box
> > with oil there should be no danger of explosion
> > because pressure couldnt build up right? 
> 
> No, but oil could leak out as it got warm and
> expanded. 
> Additionally, it would be contaminated as it cooled
> and sucked 
> air and airborne contaminants back in through the
> vent.
>  
> > Also, mabey you could help me out with this one.
> Or
> > mabey you know someone who can.
> > 
> > I just wound a new primary, its a flat spiral, 20
> > turns, 1/4" steel guy wire spaced about 1/4"
> apart. 
> > The inner diameter is 7.5" My secondary is 4.5"
> > diameter and 20" high (902 turns) of #24.  The
> tank
> > cap is ~10nf (wine bottles) and the tank input is
> 10kv
> > -at- ~133ma.  
> > I can't get corona discharge of no more than 7",
> my
> > top load is a spheroid of about 5" diameter. The
> first
> > turn of the secondary is 1 inch above the first
> turn
> > of the primary. Whats wrong, why do i get almost
> no
> > discharge? Should I adjust the coupling by
> lowering
> > the secondary a little? (I have to cut a hole in
> the
> > base of the primary to do this and i havent the
> time
> > to do it yet.)  
> 
> Steel is the wrong choice for your primary. It is a
> poor 
> conductor and its ferromagnetic properties together
> with non-
> lamination will influence secondary frequency and
> losses as 
> well. Assuming your peal primary voltage (i.e. gap
> setting) is 
> 10kV, the per-bang energy available to the secondary
> if there 
> were no losses would be only 0.5J which is not high.
> However, 
> you should be able to do better than 7" with that
> energy so it 
> looks as though there are losses you could do
> without in your 
> primary.
 
> > My less than spectacular other primary, (#12 wire
> > wrapped on a old 12"  laundry detergent bucket
> > (anything but even wire spacing)yielded sparks of
> up
> > to 18". 
> 
> What conductor did it use?

  Copper 
> 
> Regards,
> malcolm
> 
 


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