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an idea for a cheapie solid state coil



Subject:  an idea for a cheapie solid state coil
  Date:   Thu, 8 May 97 14:17:07 UT
  From:   "William Noble" <William_B_Noble-at-msn-dot-com>
    To:   "Tesla List" <tesla-at-pupman-dot-com>


thought experiment - consider the following:

PC power supplies are 65 to 250 watt.  Dead ones cost a dollar or two at
swap 
meets (what we here on the west call ham fests).  They are a switching 
regulator.  Newer ones switch in the 70 to 300 Khz range which is in the
ball 
park for tesla work.  A 200 watt supply will output lots of 5V current
(20 
amps or more) with smaller amounts of 12V.

Remove diodes for -5, -12 vdc outputs - they won't be needed.  remove
diodes 
for +12 and +5 and see if the circuit oscillates.  (fix until it does).  
Sometimes there is feedback from 5V, often a crowbar on 5V.

Once the thing oscillates, take the 5V winding from the Xformer and
bring it 
out of the supply and use it to excite a primary coil directly.  Adjust 
inductance of primary so the supply doesn't go into current limit - you
might 
be able to wind a primary (helical) near a 3 or 4 inch dia secondary,
and then 
slide some ferrite rods in the bottom to adjust inductance.

Most newer supplies use PWM chip - if you look up the specs on the chip
it 
might let you have lots of fun control over what the supply does.