Re: Wintron transformers

On Thu, 12 Jul 2001 18:47:02 -0500, Joe Bachmann <joe.bachmann@newmail.net>
wrote:

>Thank you for the info... With that in mind, I found a site that looks like it may sell just the thing we're after:
>
>http://www.emcohighvoltage.com/emcoindex.htm
>
>Link to section I am referring to: http://www.emcohighvoltage.com/crt.PDF
>
>I am looking at the CRT-200 or 6000 series.. This may be easier than designing something, however I don't know the cost..
>
>JB

Those are cool! If they are cheap enough, forget Wintron.

Designing a supply using an off the shelf flyback is not easy.

This is my take at doing so. This is more Rodger Boot's field, but here goes...

Everyone seems to forget the flyback circuitry needs a yoke (or the equivalent
inductor -- this is a tuned circuit and must remain so to work properly) in
order to produce the HV needed. The second thing shrugged off seems to be HV
regulation -- needed to keep the picture from growing and shrinking as the
vector count on the screen goes up and down.

The schematics I've looked at all run the flyback's primary on rectified 120vac.
This requires that a isolation transformer be used (to avoid electrocution -- a
bad thing). HV regulation on the raster CRTs I've looked at is done in a
specialty chip that also controls the horizontal (and sometimes vertical) sync.
It supplies the free running oscillator that is locked onto the HV sync pulse
when detected. Way over kill for what we need. But if we design the oscillator
ourselves, we need to design the regulation circuitry also.

You will also need the current transformer that is used to drive the horizontal
deflection transistor.

All and all, to use a flyback, you need to design a large part of a horizontal
sweep circuit that needs to be run with a isolation transformer. It gets
cumbersome and expensive -- even with a $17 flyback.

Things get much simpler when you start with a properly wound HV transformer (not
a flyback). Just look at how simple the HV sections of X/Y monitor are compared
with raster monitors. Raster monitors use flyback simply because the Horizontal
section is already there, and is real easy to tap into to get the HV needed.
That and flybacks are a very efficient way off generating HV.

The opposite is not true, it's a pain to start with a flyback and build the
horizontal circuitry to support it.

These are the reasons that seemed to have stopped every attempt at building an
HV replacement since I been reading vectorlist. Not the threat of lawsuits.

On the other hand it looks like "low cost" 350 series would run all the B&W
vectors, and the CRT 200 would probably run the colors -- even the filament in
an amplifone! Very cool!

-Zonn
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Received on Thu Jul 12 21:13:26 2001