need recommendation for digital multimeter

I like the Thurlby-Thandar multimeters. The 1906 - which I've used in two different jobs - offers more than you ask for at a very reasonable price, including four terminal resistance measurements and the facility to log 100 successive measurements into local memory.

Their 1604 - at half the price - does pretty much exactly what you ask for.

Clive Sinclair was involved when Thurlby-Thandar started up, but they managed to stop him messing up their quality control fairly early on, and they do seem to have managed to take advantage of Clive's genius for finding really cheap ways of doing things, without getting stuck with his compulsion to make the product too cheap to be reliable.

-- Bill Sloman, Nijmegen

Handheld or benchtop? You need to measure high voltages/currents? Need or want frills such as capacitance, hFE, temperature, frequency? Want RMS measurement? Need absolute accuracy? Or just resolution/linearity? Budget range? < $10? < $100? < $1,000? < $10,000?

This is a nice one in the highest bracket: ;-)

Kind of nice to see my 10uA current sources reading 10.0024233 uA without adjustment. ;-)

either

no

not needed

not needed

preferable

< 400? is that reasonable?

Good questions, I didn't know I would get so much detail from y'all, thank you.

Yikes, what does a beast like that cost?

Any idea how it works?

That last digit is 0.1 pA, about 600,000 electrons per second.

John

I like the Thurlby-Thandar multimeters. The 1906 - which I've used in two different jobs - offers more than you ask for at a very reasonable price, including four terminal resistance measurements and the facility to log 100 successive measurements into local memory.

Their 1604 - at half the price - does pretty much exactly what you ask for.

** I owned a TTI 1604 briefly, before returning it to the supplier ( Farnell ) as it has serious bugs.

A second sample demonstrated exactly the same bugs, so they were designed in.

The bugs were in the auto-ranging and all the ohms ranges - which could and did give completely erroneous readings.

6800 ohms reading 3940 is not good !!!!

Many of the bugs derive form the makers trying to get 4.5 digit resolution from a DMM chip that is not speced for that job.

....... Phil

Seems to be a nice meter but Phil A. expressed some concerns in another post. Also, Saelig seems to be their only US distributor, and quoted 6 weeks, $519.

So I'm still looking. Thanks.

Consider carefully what you'll be measuring.

I was elated to pick up a 5.5 digit HP voltmeter for free at a garage sale.

Took it home, hooked it up to a battery. Was very cool to see 1.31V to 5.5 digits.

But when I tried to use it for real measurements, I got

3 digits of reading and 2.5 digits of noise. I put it in the attic. Only time I drag it down is when I need to measure the voltage drop across an inch of wire.

To get any use out of a high-res voltmeter, you need a VERY controlled environment. But I'm sure you already know that. mike

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"mike"

** There is a low pas filter in line with the input of a DMM when set to read DC volts, generally set to give 3 dB attenuation at about 20 Hz with a -6 dB /octave slope above that.

PLUS, nearly all DMMs have the sampling rate set so a whole number of cycles of the AC supply frequency are included in each reading - means any residual 50 or 60 Hz ( plus harmonics ) will not affect the DC reading.

Sometimes a meter with sampling time set for use in a 60 Hz country winds up in a 50 Hz one and vice versa.

...... Phil

If you need that level of accuracy, give some thought to how you plan to calibrate from time to time, and the cost of doing so. Precision is much less costly than absolute accuracy and sometimes is more useful.

Chuck

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Always good advice, and I have thought about that, thank you.

Let me be less tactful... Most people, including (maybe especially) very smart engineers who graduated at the top of their class, don't think things through. They take a quick look at (part of) the problem, count the digits, go buy one without considering the further implications of their choice and spend a LOT of time trying to make the rest of the system live up to that expectation.

My intention was to expose this issue without making any accusations. Many problems can be better addressed with less brute force. Anything that requires 5.5 digits of repeatable measurement is gonna be a nightmare. Sometimes, you gotta do it. But avoid at all costs.

That's really great IFF line (related) noise is what is corrupting your reading.

There surely are applications that require high resolution. My statement was that I found the extra two digits of noise less useful than the bench space taken up by the meter.

And we haven't even started talking about all the issues that affect accuracy.

mike

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** Go ahead - make my day ......

** Which is very often the case.

And since noise above 20 Hz is attenuated that only leaves very low frequency noise as a possible culprit.

** But there is no need for ANY such noise to be there.

YOU have failed to think the issue through.

** Betcha this one is you *whole* problem.

And if it ain't, then just add your own, external LP filter until the noise causing end digit jitter is gone.

........ Phil