Advice on electrostatic deflection CRT ?

From: Tom Uban <uban_at_ubanproductions.com>
Date: Wed Jan 21 15:04:07 2004

At 09:39 AM 1/22/2004 +1300, you wrote:

>Steve is quite correct. Deflection data from any 12 inch CRT would do for a
>ball park startup and you could go from there-main problem is establishing
>the tube connections and finding the correct filament voltage. Check the cct
>of an old Tek scope (for example) to see how the various tube electron gun
>elements are connected and powered. Often the connections can be see through
>the glass if you know what you are looking for. The filament pins are of
>course a low resistance to each other.

I don't know of any scopes with a 12" diameter CRT, but it is certainly a
good starting point for experimentation. I should be able to dope out the
pins as the neck of the tube is about 3-4" in diameter and is clear.

>However-- from the type no you quoted you have a P31 phosphor CRT-is this
>really what you want? P31 is, I think, long persistence, and would be no use
>for any application needing a fast screen refresh rate due to the long
>phosphor decay time. It was often used in PPI radar displays etc.although
>such CRTs of course had a magnetic deflection system.

Yes, it is a long persist phosphor, used in an old vector display console. I
am assuming that the deflection is electrostatic as there are no external
deflection coils.

There is a chance that I may be able to get the tube specifications from
the manufacturer. I've been in contact with them and they are searching
for the information.

--tom

>DaveB
>Christchurch, NZ
>
>----- Original Message -----
>From: <melamy_at_earthlink.net>
>To: <cctalk_at_classiccmp.org>
>Sent: Thursday, January 22, 2004 8:27 AM
>Subject: RE: Advice on electrostatic deflection CRT ?
>
>
> > forgive any inaccuracies to those who may know better (or can remember
> > better...)...
> >
> > what you will be interested in finding out is the deflection per inch
> > voltage required for the beam deflection. I seem to remember ranges of
> > 10-50 volts per inch. You will need to know the filament voltage of course
> > and its amperage. What I don't recall is what the necessary acceleration
> > element voltages were. The grid was used to control the beam brightness
> > with a greater negative voltage with regards to the other elements dimming
> > the beam (I think). The electrostatic plates should have the beam in
>center
> > with zero volts and then deflection is accomplished by positive and
> > negative voltages. If you can not find precise data then you can find the
> > full deflection voltage by experiment once you have a center beam. I
> > suspect that the long tube should give you a more sensitive tube in that
> > the deflection voltage may be on the low end of the range.
> >
> > best regards, Steve Thatcher
> >
> >
> > Original Message:
> > -----------------
> > From: Tom Uban uban_at_ubanproductions.com
> > Date: Wed, 21 Jan 2004 09:50:46 -0600
> > To: cctalk_at_classiccmp.org
> > Subject: Advice on electrostatic deflection CRT ?
> >
> >
> > Hello,
> >
> > I have what I believe is a custom CRT. It has a 12" round face, is
> > approximately 20" long, and uses electrostatic deflection. It was
> > manufactured by Thomas Electronics Inc. in Wayne NJ and is hand
> > marked as model number 12E35P31, 12-2-78.
> >
> > I am hoping to put this CRT into service and need to come up with a
> > set of specifications which will likely work with it. What other
> > physical information do I need to take from the CRT in order to
> > help determine the specifications?
> >
> > Any suggestions for creating the power supply and deflection drive
> > electronics are welcome.
> >
> > Thanks!
> >
> > --tom
> >
> >
> > --------------------------------------------------------------------
> > mail2web - Check your email from the web at
> > http://mail2web.com/ .
> >
> >
> >
> >
Received on Wed Jan 21 2004 - 15:04:07 GMT

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