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Nightvision 1st September 2005 12:09 PM

1200V amplifier
 
People,

I want to build a sor of amplifier which can make 0 to 1200V output out of 0 to 5V input (may also be inverted).

It has to be a lineair control. It also has to be in SMD. Many transistors or FETs can't go further than Vce and Vbe of 200/300V, so I have to make something which can handle the 1200V.

Anyone has an idea?! Thanks!

Martijn;)

jackinnj 1st September 2005 12:33 PM

good luck finding SMD resistors for KV operations. KV transformers are also special beasts -- once you go over 600V the wire and between-layer insulation becomes quite specialized and expensive. I don't know what the situation is on that side of the Atlantic, over here HV transformers are relatively easy to obtain from military surplus outlets and ham radio flea-markets.

in fact, one of the easiest ways of implementing this design is to regulate the primary side of a transformer, picking up the error signal from the secondary side -- think of it as a linear supply using switching power control loop principles. instead of controlling the duty cycle of a switch, control the amplitude of a primary side amplifier -- you can opto-couple the feedback control just as in a SMPS.

phase_accurate 1st September 2005 12:38 PM

What power and bandwidth are you looking at ? Is it for driving a large ESL, a small piezo actuator, ..... ?

Regards

Charles

jan.didden 1st September 2005 12:54 PM

Quote:

Originally posted by jackinnj
good luck finding SMD resistors for KV operations. KV transformers are also special beasts -- once you go over 600V the wire and between-layer insulation becomes quite specialized and expensive. I don't know what the situation is on that side of the Atlantic, over here HV transformers are relatively easy to obtain from military surplus outlets and ham radio flea-markets.

in fact, one of the easiest ways of implementing this design is to regulate the primary side of a transformer, picking up the error signal from the secondary side -- think of it as a linear supply using switching power control loop principles. instead of controlling the duty cycle of a switch, control the amplitude of a primary side amplifier -- you can opto-couple the feedback control just as in a SMPS.



An easy way would be using a standard audio power amp and have it drive a step-up transformer that can handle the voltage levels. That gives you galvanic isolation, low price (an LM3886 would be great for this) and level control.

Jan Didden

Hanzwillem 1st September 2005 02:17 PM

Also, check out Apex microtech
http://eportal.apexmicrotech.com/mainsite/index.asp

They have some piezo drivers and stuff. Also some usefull articles on precautions using high voltage opamps.

succes.

jan.didden 1st September 2005 02:23 PM

Just thought of something: this 1200V is that peak-to-peak or RMS or what? if it is p-p and balanced you can use a tube power amp and take the output from the primary of the output xformer.

Jan Didden

jackinnj 1st September 2005 02:29 PM

Quote:

Originally posted by janneman
Just thought of something: this 1200V is that peak-to-peak or RMS or what? if it is p-p and balanced you can use a tube power amp and take the output from the primary of the output xformer.

Jan Didden

that's what we used "in my youth" when doing Electron Spin Resonance experiments -- seems like a shame to have used a McIntosh amplifier, but what the heck, the U.S. Navy was paying for it.

EC8010 1st September 2005 03:21 PM

Quote:

Originally posted by jackinnj
that's what we used "in my youth" when doing Electron Spin Resonance experiments -- seems like a shame to have used a McIntosh amplifier, but what the heck, the U.S. Navy was paying for it.
Surely the amplifier found other uses when it was "off-duty"?

SY 1st September 2005 05:33 PM

Quote:

Originally posted by jackinnj


that's what we used "in my youth" when doing Electron Spin Resonance experiments -- seems like a shame to have used a McIntosh amplifier, but what the heck, the U.S. Navy was paying for it.

My dissertation work involved the use of B&K 4003s to measure infrared spectra. For some reason or other, those mikes never seemd to be around unless I was physically in the lab.

Why was the Navy doing ESR?

pinkmouse 1st September 2005 06:28 PM

Quote:

Originally posted by SY
Why was the Navy doing ESR?
Re-run of the Philadelphia Experiment? ;)


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