Re: switched mode power supply

To: tesla-at-poodle.pupman-dot-com
Subject: Re: switched mode power supply
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 23 Mar 1997 23:09:38 -0600
Approved: tesla-at-stic-dot-net
Subject: 
        Re: switched mode power supply
  Date: 
        Sun, 23 Mar 1997 06:32:24 +0200
  From: 
        Kenneth Aaron <kennetha-at-geocities-dot-com>
    To: 
        Tesla List <tesla-at-pupman-dot-com>
    CC: 
        tesla-at-pupman-dot-com


At 03:19 PM 3/22/97 -0600, you wrote:
>
>
>
>Subject: 
>        Re: switched mode power supply
>  Date: 
>        22 Mar 97 13:56:19 EST
>  From: 
>        Alan Sharp <100624.504-at-CompuServe.COM>
>    To: 
>        "INTERNET:tesla-at-pupman-dot-com" <tesla-at-pupman-dot-com>
>
>
>Kenneth wrote:
>
>>> I have had great difficulty in obtaining a cheap 2kw transformer,
>>> so my plan is to create a SMPS and step up the voltage. the idea i
>>> have in mind is a design that operates the switcher at the self
>>> resonant frequency of the module so i get max efficiency. has
>>> anyone tried this before ? How do the spark gaps and caps handle
>>> the 30..80khz input to them ? is anyone interested in the schematics
>>> of the SMPS ?
>
>Malcolm replied:
>>What module? You can run a switcher and feed the secondary like a 
>>magnifier. A number of people have done it. You don't need a gap.
>>Harri and Alan are experienced operators and Mark Barton has done it 
>>to about 8kW CW and around 40kW pulsed carrier. A low frequency 
>>resonator <<100kHz is the key to efficiency in the switcher.
>
>I'm with Malcolm on this. It would be possible to build a SMPS to supply
>say 6Kv at 60ma and then to full wave rectify this, smooth it and use
>the
>DC supply to run a traditional spark gap.
>To do what you propose there would be no need for a sparkgap or a
>capacitor
>- you adjust the frequency of the SMPS to the resonance frequency and
>then
>You could put this into a primary coil but there are a lot of problems.
>
>1) Energy is transfered from the primary into the secondary but it also
>comes
>back down again - at a much higher voltage and high currents.
>I tried a very simple rig:
>
>PWM chip ----- FET ---OOOprimaryOOO---- +ive
>I found that while say 1A was being fed into the circuit, 4A say
>(average) was
>being switched by the FET and 3A was fed back onto the +ve rail via the
>protection diodes. (with out these diodes overvoltage killed the FET)
>
>2) Mark Barton ran this at 8 - 10kW using a full bridge. The secondary
>was
>an pvc oil drum, the primary was (from memory) 18" high 3' diameter.
>But he had massive problems with strikes to the primary. He blew a lot
>of FET's.
>
>I now use Duane Bylands magnifier arrangement:
>
>ground----OOOSMPS secondaryOOOOO------OOmagnifier coilOOO-----toriodal
>
>the SMPS supplies 3kV. The magnifier coil is a large polythene bucket -
>sold
>for homebrew beer. about 1000 turns of 0.4mm copper wire. (80kHz)
>
>I would be very interested in seeing your schematic for a SMPS.
>
>Have fun,
>
>Alan Sharp (UK)
>
>


it's still an idea. if it works it should be sreat, no tonnes of iron
and
copper like traditional xfrms.
----------------------------
Kenneth Aaron 
E-mail : kennetha-at-geocities-dot-com
http://www.geocities-dot-com/SunsetStrip/8736/
----------------------------