Advice on electrostatic deflection CRT ?

From: Dave Brown <>
Date: Wed Jan 21 14:39:01 2004

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.

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.

Christchurch, NZ

----- Original Message -----
From: <>
To: <>
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
> 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
> Date: Wed, 21 Jan 2004 09:50:46 -0600
> To:
> 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
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Received on Wed Jan 21 2004 - 14:39:01 GMT

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