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Old 11th July 2009, 02:56 AM   #11
ncc is offline ncc
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Quote:
Originally posted by rman


I built this regulator.

http://www.glass-ware.com/tubecircuits/High_Voltage_Regulator.html Broskie regulator

It didn't work... at least I couldn't make it work.

Cheers.
I know at least one man who could make it work, see:





Here is his main site:


a very infomative site that I like very much

Cheer
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Old 11th July 2009, 04:00 AM   #12
rman is offline rman  Canada
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Hi ncc.

From the page of your second link:

Quote:
There is a 1F capacitor connected across the load resistors, I found that with a purely resistive load the regulator will not 'power up'.
Maybe that was my problem when trying to test it!

I still have this thing laying around, should check it over and try again.

Cheers.
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Old 14th July 2009, 05:28 AM   #13
rman is offline rman  Canada
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After rechecking the board I found a missing connection after about a minute. Months ago when I built it, I couldn't find the flaw. It regulates voltage alright. will have a look with the scope tomorrow.
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Old 14th July 2009, 06:38 AM   #14
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Quote:
Originally posted by rman
After rechecking the board I found a missing connection after about a minute. Months ago when I built it, I couldn't find the flaw. It regulates voltage alright. will have a look with the scope tomorrow.
Hi rman,

Nice to hear that you've found the error
This regulator use a floating power supply for the reference voltage and error amplifier, I've experimented with this regulator by using a RC filter then a regulator (a LT3080) for the floating power supply, after that, high voltage output of the regulator is much cleaner than the original design.

Cheer
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Old 15th July 2009, 02:28 AM   #15
rman is offline rman  Canada
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hi ncc.

Great idea! Regulating the op amps supply makes a lot of sense to me as most op amp supplies are regulated.

Well, I had a look at the output and it is oscillating quite nicely at about 3 MHz, 0.3v pp. I put in a larger gate stopper (1k) as close to the gate as I could get. This only distorted the 3 MHz waveform.

The load for this test is a big wire wound pot set to 12.5k (20ma. @250v). It was intended for a phonostage, the regulator that is. Interestingly, when the load is adjusted to about 12.1k, the oscillation stops. The Mosfet is an IRF BC40 (found on shop floor at work). swapped in an IRF 540 and the amplitude of the oscillation rises. I really don't' know enough to account for all this. I can only conclude that layout is critical, and that mine is not great.

I guess we have hijacked this thread as the original topic seems to have disappeared.
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