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Old 10th Oct 2021, 2:57 am   #10
Join Date: Aug 2008
Location: Melbourne, Australia
Posts: 213
Default Re: 5FP7 project starting with the focusing coil.

Originally Posted by AdrianH View Post
Thanks for the suggestion Dalek I will have a look at them, the magnetic control I seem to remember using in an old welding set many years ago, at least I think it used that principle.

I do have a Velleman kit PWM controller that has a blown output device. I was going to get that fixed and see if the frequency is fast enough to drive a LOPT and get HT that way.

But I would really like to build it all with a valve if I can using one as a RF osc placing it all in a screened box. Well that's the plan at present, it just takes time, patience and brains, I am starting to get in short supply of two.

Its Harry BTW ; ) i like to do the HV with mains transformer up to a point as it is cleaner than a high frequency inverter as you can get a dirty DC result in the display as i found out on the Beast monitor i swapped to a mains multiplier got 3kV which was fine for that one.

I had the same idea to do the DC side of it all with Valves too but i got talked out of it for now ..if any thing i can see its needs with the power supply i have made .

Any case perhaps because i used the high frequency inverter on a electrostatic tube this was the problem i have to admit never have had this problem with a magneticlly deflected tube so you should be right ...with your idea of a valve inverter and a magnetic amplifier varying the supply this would think work ..i was meaning to ask why do you need it variable ? if you know the tubes data you aim for its normal operating range voltage.
But does help running it up how it works on lower voltages used the idea on CRT i had no idea no data .

I am using a 3bp1 the supply for it is - 1200v at the moment which should be workable on that .

Do you have any links to any of your circuits as i am still a baby with doing all this with valves i found your page and interesting seeing your past CRT work ...i am glad you pointed out the CRT dot limit size is a problem on higher line rates on small CRTS reason for use of larger CRTS and most people have no idea of this problem .
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