High Voltage OP AMP needed

Hi,

Im looking for an OPAMP which can deliver +/- 60 V (120 V nom) or more in the 1 kHz range. No significant current throughput is needed. Does anyone know of a manufacturer? The best I can find at TI.com is +/- 45V.

If they are not to be had, how does one go about creating a 1 kHz +/-

60V sawtooth signal?

Casper

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Reply to
John Fields

Or perhaps simpler, a high voltage ramp generator. The SuperTex AD-D12 goes up to 500V, but the example oscilloscope trace in the app note demonstrates a a +/- 50V (100v nom) 1 kHz circuit very close to your requirements.

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Reply to
orphic.mysteries

An opamp can not create a sawtooth and it would need a much larger bandwidth than the repetition frequency. Make a current source charge a capacitor, (optionally buffer it with a complimentary emitter follower for higher current capability), and trigger a thyristor to the negative rail when the desired voltage is reached. cheap and simple.

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ciao Ban
Apricale, Italy
Reply to
Ban

"Casper Budtz-Jørgensen"

** Err - a small AC supply transformer will step up the voltage from an op-amp or signal genertaor to that level.

Something with a 230 volt primary and say 12 volt secondary used in reverse.

...... Phil

Reply to
Phil Allison

On Fri, 23 Mar 2007 14:49:39 +0100, Casper Budtz-J?rgensen Gave us:

Dude, the op amp is a driver. Use a transistor or FET after it for the real work.

Reply to
MassiveProng

I'll second the Apex recommendation. I've used their PA84 to deliver a +/-100V signal biased at 200 V (eg +100 to +300 swing) at well over 20 kHz. It was humbling to use one of their slick little TO-3 amps to replace my entire prior HV amp design, which had series- stacked transistors and fancy bias to be able to handle the voltage range that the Apex handled without fuss.

Best regards.

Bob Masta D A Q A R T A Data AcQuisition And Real-Time Analysis

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Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!

Reply to
Bob Masta

Yup. I've used Apex products, and it *is* humbling. Also, a little pricey and typically long lead times. The PA84 shows almost $150USD and lead time of 5 or 6 weeks.

There are a couple of options available to the OP if Apex product is looking a little uncomfortable. First off, he can bootstrap a regular voltage op amp to handle the higher volotages (a trick developed by the National Semi gurus in the early days of IC op amps, AFAIK). Here's a good link which goes into a little detail on how to do this on the cheap:

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Another, much easier way to skin the cat might be to just do an application-specific circuit. Since the OP basically wants a 60V sawtooth, he could use a transistor constant current source to charge up a cap, and then use a 555 to drive an NPN transistor with short

1KHz pulses to discharge. Relatively easy. The OP might want to post again if he wants more details.

Cheers Chris

Reply to
Chris

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Nice parts.

I used one of their PA141\'s a few years ago as a piezo driver for an
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Reply to
John Fields

On Sat, 24 Mar 2007 11:07:45 -0500, John Fields Gave us:

A piezo stack amplifier we designed had two 2kVA transformers and did

20 to 20kHz, the stack was like a 1000 wafer linear motor that was driven at 800 Volts.

It was used on a lathe in a very controlled micro-machining tool head that had micron level accuracy. It was used to cut plastic contact lenses with optical quality surface Q.. One application was 1 inch diameter lenses used one race horses.

The tool could cut a square shaft out of a spinning rod on a lathe.

One could squeeze the stack and it would exhibit voltage as well (of course).

Our client was:

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Reply to
MassiveProng

In message , Casper Budtz-Jørgensen writes

Well back in the '80s I used a signal generator and a HH amplifier( like the ones Slade used back then, the ones with the green electro-luminescent panel)

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Neil J. Harris
Reply to
Neil J. Harris

Is Figure 6 another "EDN IQ test" ? (dodgy EDN schematic)

Figure 6:

it looks to me that RB and RF should connect to Vout where they cross. or am I misunderstanding the purpose of RB?

Bye. Jasen

Reply to
jasen

Well thanks to everyone - dude included - for their replies. I certainly got the info I need. I will check out the Apex amps. In case you are interested, I am making a Langmuir probe system for plasma diagnostics. I have a working system using an Exar2206 wave generator to drive a handful (its a multiple probe system) of OPA452 Op Amps that deliver the

+/- 40 V voltage to the electrical probe tips. It turns out that +/- 40 V doesnt cut it diagnostically - I need the +/- 60 at least. Hence the query. I imagine the Apex should be able to do the job with a minimum of config change.

Thanks again,

Casper

Casper Budtz-Jørgensen wrote:

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=?ISO-8859-1?Q?Casper_Budtz-J=

(snip)

I agree. They lost a dot.

Reply to
John Popelish

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