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Registered Member #60240
Joined: Mon May 16 2016, 07:01PM
Location:
Posts: 304
Hi Patrick
Here are first results of measurements of the frequency dependence of a 25 kV high voltage amplifier. Equipment: TEK 6015A and TEK 7854 with 7A26, y: 5kV/division.
A linear response of the amplifier can be seen only in the first picture at 0,1 Hz. At 1 Hz and at 10 Hz strong distortions are visible. Unfortunately this amplifier is very slow. I would like to get one which is faster by a factor of 10000.
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
I was curious about this myself, so I looked it up. It's a DC supply.
He's just controlling the 0-5V external control voltage with a sine wave. Neat little supply though.
If you need a 25KV source at 10KHz or wideband, they can get very expensive. Amp-Line has a standard mosfet amp that is wideband which outputs 28V at high current, and then they have you add an external transformer to change the voltage ratio. I like their mos amp because it's spec'd from 10Hz to 800KHz. I'm still working on getting rid of the distortion on one of these, off and on, it's a pain.
Everyone else will just suggest making a flyback supply smps.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Hazmatt_(The Underdog) wrote ...
Everyone else will just suggest making a flyback supply smps.
Well i think its a square wave that will be most useful, thats what we all use to calibrate our probes off that little frequency generator on oscilloscopes. but dividing 5 volts by 1000 is just to sketchy. Its really got to be 3 kV or so, so youd have to make your own device.
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
Patrick,
Ideally you want a pure sine wave because it's a single tone. Square waves have infinite harmonics, so that is not useful for finding the frequency response of the probe.
BUT, since we rarely, if ever care about NIST traceability, that is not really important is it.
The loaded secondary side output of a flyback SMPS, into say 100K ohm 100 watt resistor should give you a reasonably pure sine wave at the operating frequency, even if the input drive is a square wave.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Hazmatt_(The Underdog) wrote ...
The loaded secondary side output of a flyback SMPS, into say 100K ohm 100 watt resistor should give you a reasonably pure sine wave at the operating frequency, even if the input drive is a square wave.
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25 kV amplifier frequency dependence
