AC voltmeter suggestions

On a sunny day (Tue, 5 Oct 2010 13:46:02 -0700 (PDT)) it happened George Herold wrote in :

A few moments in spice, a fast opamp, fast diode[s], make a peak detector, a 10$ multimeter. Or stuff the output from the peak detector into a PIC ADC, power it from the RS232, read out 10 bits accuracy on the PC. A LCD connected to the PIC s a possibility too.

Hey! No "Use a PIC" posts allowed without a full schematic and source code listing!

Cheers! Rich

On a sunny day (Tue, 05 Oct 2010 15:22:36 -0700) it happened Rich Grise wrote in :

Go away troll. You do not make the rules, you are a violation of those.

OK I could make something myself. But a nice bench DMM/ AC voltmeter would be useful. I'd like another digit or so past what my hand held DMM gives me.

There is/was a nice DMM by HP. I can't recall the model number. I was just trying to save myself web search time.

George H.

or,

Why not? And mostly Jan was suggesting a fast opamp and diode. I guess I wouldn't make a peak detector but a precission rectifier... I lose the "true rms" that way, but at the moment I'm looking at ratios of sine waves and the true rms doesn't matter.

George H.

Why not?

Oscilloscope?

-ek

On a sunny day (Wed, 6 Oct 2010 17:36:53 +0300) it happened "E" wrote in :

I agree, AC meters were in > 60 years ago. Usually you want to see the waveform too. There may be cases where very precise RF amplitude measurements are needed, just that I cannot think of one that would take 8 1/2 digits or even more then 3.

.com...

Yeah I've been using the 'scope to do this. But I really want a bit more resolution than the 'scope can give me. I also find that to get good numbers with the scope I need to keep switching the 'scope channels because the gain is not quite the same on each channel. My hand held DMM (Fluke 189) works great, but the AC volts craps out above 100kHz. I've done a bit of searching and this seems to be standard. (Some go to 300kHz but that's about it till you get into the real high end meters.)

George H.

s.com...

d,

then 3.

Well I don't need 8 1/2 digits. 4 or 5 is plenty, but I would like it to go to 1MHz.

I'm just trying to characterize some ~1% filters. (10 Hz to 100kHz.) I've got a one point calibration method that seems to give me the corner frequency and Q to good accuracy. I'd like to plot out the filter transfer function, fit it with a model and extract the corner and Q from the fit and see how well this agrees with the single point calibration.

George H.

On a sunny day (Wed, 6 Oct 2010 09:21:07 -0700 (PDT)) it happened George Herold wrote in :

An opamp peak detector with your Fluke connected to it should be fine. Almost any opamp cookbook gives examples of simple peak detectors.

What happened to your sense of humor, Jan?

On a sunny day (Wed, 06 Oct 2010 12:13:39 -0700) it happened Fred Abse wrote in :

Sometimes there is a need to be serious. he has been screaming that s*it over and over again. He could use the same time to try to program one, and make the source code available. He is justatroll. It is just a stupid remark as requiring us to design the circuits for any question any poster comes up with.

If people have nothing to contribute, then they think they make themselves useful by playing police man. some otehrs do that too. Would not surprise me a bit if it is thanks to one of those that aioe neweserver has banned s.e.d No I was not referring to AlwayWrong.

Hell you may be glad anything is on topic here, the SNR is sometimes signal

Can a horse's ass have a sense of humor ?:-) ...Jim Thompson

I guess the thing is probably that this is s.e.design, and not s.e.basics, so it's OK to tell newbies "Use a PIC!" without telling them the circuit, the code, or how much the development system will cost and what the learning curve is like.

And, anyway, I wouldn't use a PIC on a bet - bank switching is evil.

Thanks, Rich

On Wed, 06 Oct 2010 19:27:37 +0000, Jan Panteltje wrote: ...

No, not _ANY_ question, just the ones that blow off the OP with that "Use a PIC!" crap.

Cheers! Rich

useful by playing police man.

And you think that blowing off the OP with a "Use a PIC" is a contribution?

Sheesh!

Thanks, Rich

On a sunny day (Wed, 06 Oct 2010 12:44:36 -0700) it happened Jim Thompson wrote in :

I dunno about that, but a repugblican? No way.

The HP 3457A can be had for reasonable money. Accuracy does fall off a bit between 100KHz to 1MHz. If you don't need the accuracy that a 3458A has and you can forgo the digital readout, check out an old analog HP 3400A, it's good to 1MHz +-1% and 10MHz +-%5. Best of all you can get 'em pretty cheap.

Only 99 cents so far: