Arbitrary signal generator

[Skogsgurra]

I need an arb for a test. Must have output with at least +/- 20 V at 50 ohms load. Slew rate is important, too. Should be able to deliver 200 V/microsecond with "straight" edges i.e. no jaggies, at least not visible on a scope. Repetition rate not critical as long as I can have at least 100 Hz, but more is better.

Any ideas out there? Used or surplus is OK.

 

[nbucska]

If it is for "A" test, I am sure you can get around it...
What are you trying to do ?

<nbucska@pcperipherals.com>

 

[IRstuff]

It's not clear whether you simply need a programmable pulse generator or a true arbitrary waveform generator.

Nor have you given sufficient detail as to the voltage or frequency resolution required.

TTFN

 

[Skogsgurra]

nbucska and IRstuff

I need it to simulate the voltages that exist at the ends of an asynchronous induction motor. This signal is a mixture of capacitively and inductivly coupled voltages which mainly reflect the switching edges of the PWM drive. Hidden in these voltages are signals that are quite steep. These signals stem from discharges in the bearings and are telltales that electric discharge machining (EDM) is present in the bearing.

We are developing a &quot;Bearing Predictor&quot; that shall identify these EDM signals and we are now in the final testing phase and need to verify that we can identify and discriminate the different signals.

It is not very practical to move one of these motors into the lab - we are talking smoke stack fans or wet section drives in a paper machine with 300 to 2000 kW output - so my only possibility is to generate the signals using an arbitrary generator or a signal generator.



As for resolution and frequency range, I am afraid that I cannot give you any better specification than I already have (Assuming that 8 bit is the lowest amplitude resolution - plus range switching and that the same applies to frequency. Of course I do not expect that someone built a generator with such bad specifications, but it would be enough for me). The edges are important, it shall be possible to set the slew rate between 10 and 200 V/microsecond. The output impedance is important, too.

But I think that these things will work themselves out if I can find something that fulfills my original posting.

Thanks for your co-operation guys.

 

[Skogsgurra]

Problem solved!

I found a LeCroy 9109 arb on eBay. It is a dual channel unit with +/- 10 V into 50 ohms. By programming the two channels to go in opposite directions, I can (almost) have +/-20 V into 50 ohms. I have to increase the load impedance to 100 ohms, but that seems to work well enough.

BTW: eBay worked very well and I got my generator at a very, very good price. With manual! Now, let's find out how well UPS does its thing.