Re: Laser Power Supply Components

From: 	chuck seguin[SMTP:seguinc-at-algonquinc.on.ca]
Reply To: 	seguinc-at-algonquinc.on.ca
Sent: 	Friday, August 08, 1997 7:43 AM
To: 	Tesla List
Subject: 	Re: Laser Power Supply Components

Tesla List wrote:
> From:   Rscopper-at-aol-dot-com[SMTP:Rscopper-at-aol-dot-com]
> Sent:   Wednesday, August 06, 1997 3:44 PM
> To:     tesla-at-pupman-dot-com
> Subject:        Laser Power Supply Components
> To the higher power nuts:
> I just disassembled (Jonny5) a CO2 cutting laser power supply that was being
> scrapped due to the laser being trashed.  Here's what I scrounged:
> 1)  Transformer - logo TECO 208,215,240VAC input, no output on the xformer,
> but the power supply controller was variable from 1.5 to 3KVDC.  It was wired
> with...
> 2)   4 diodes labled KHP6, EDI 8438 can anyone cross these??  They were in a
> full bridge configuration so I assume the xformer is about 3KVAC.  These
> diodes are big - 1x1x5inches 12 AWG connecting them.
> 3)  2 GE C152P 125A 1200V SCRs were used along with some 1foot long 225W
> 1,25,and 1K resistors for a pulsed mode operation.
> 4)  2 chokes(?) were in line made from about 25lbs of 8AWG wire each - the
> only core was a 1/2inch bolt holding them down. One had nice 1/4inch circles
> of phenolic(sp) - could be used for rotary gaps??
> 5) A cool high current switch that looked like an old starter motor relay
> only 115VAC operation and poles made of 1/2inch rods of tungsten(?) and a
> plate washer for center pole.
> The xformer was protected by a dual 30A breaker, so I'm guessing it ran at
> about 20A.  The secondary wire looks to be as thick as 23AWG wire, so it
> should be able to put out some good power.  It weighs in at about 125lbs!
> dimensions are 7X10X12. The xformer was open to air with only a layer of
> enamel on it.
> Has anyone used this type of transformer before for a TC???  Can anyone get
> specs on these diodes (they don't cross ref in my books)??
> Scott C
Good Morning Scott, and everyone else;

I have a supply such as yours.  Mine was taken from what is known as a
Transversally Excited Atmospheric (TEA) CO2 laser.  The XFMR I have can
put out, however, 30kV at an unknown power level.  I have put in roughly
3kVA when running my design.

The entire supply is similar to yours.  The output of the XFRM is
coupled into a full wave bridge and the output of the bridge WAS
connected to a group of paralleled resistors (wire wound) to form a 333k
limiting resistor.  From there this voltage was sent to a divider
network to provide a 10000:1 voltage ratio to permit output voltage
measurements.  This whole structure was submerged in oil and capped
off.   The HV output was passed through an opening in the top and
carried on a length of RG-8U (.5" diam) coax cable.

I have removed the limiting resistance and connected the output
directly, this provides me with incredible DC and phenominal current for
my design.  It operates (the TC) very well with only a static gap with a
spacing of aprox. 5/8".  The coil has pulled off arcs 6 feet long in
open air.  FYI; the secondary is 8" diam X 24" long, #20 wire, close

It appears that your supply is a good one.  Please verify the output of
the XFRM, I strongly doubt you are spect at only 3kV.  CO2 lasers need
to operate at considerably higher voltages, especially if it is a
cutting laser.  Please inform me of the lasing cavity and its possible
recovery; might be interested in refurbishing it.

Have fun with your new supply and look out for a seperate post I will
generate regarding the use of DC.  I have seen another design to be
built by one of the experts on the list which involves a huge coil
operated on 3 phase and rectified to DC.  I have some serious questions.