Digital Multimeters

It took me about 5 years to get used to autoranging. Every time I used such a meter on line level voltages I'd be thinking, "what if the meter is only 'expecting' a mV level input from last time I used it??" Even now I still get this uncomfortable feeling from time to time.

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Not bad, but a bit of 'punctuation' for the frequencies wouldn't go amiss. And a proper scale in dBm for "amplitude" would be nice!

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There is a linear / log select button:

noise at about -22 dB

If you want a cheaper frequency meter:

but that does not go to GHz...

With xpsa I use an temperature controlled rtl_sdr stick:

1 ppm is not bad for a spectrum analyzer. my rtl_sdr stick is about .5 ppm

Good enough for me,

Even some star gazing radio telescope guys were playing with it and had some suggestions. Cannot be that bad. If I need an other feature I just write it.

It is just a game, 'tronix :-) Most measurements are relative anyways, I do have a 10MHz rubidium reference from ebay:

This is NOT me featured in this story from Germany:

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I *really* wish I could be satisfied with software solutions to measurement requirements, but I just can't. I'm one of those who has to have a bespoke piece of hardware for every contingency; rooms full of the stuff. All high-end pro gear from the era when stuff was big, heavy and very expensive. Nightmare!

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Ok, so then I challenge whether the isolation of non-safety-rated ethernet transformers is really that much of a special advantage in a DMM when compared to something like USB without those transformers. In both cases, there would have to be additional safety rated reinforced mains voltage isolation between the measurement circuits and the data interface.

Now, a safety-rated-mains-insulated ethernet transformer might be a much more interesting thing.

Ooh! Just googled it and they do exist!

PS

Not sure what you mean by punctuation, but you can just move the red line over the point you want info of, and the exact frequency in Hz will be displayed middle field one down. The offset to the last position as well as to the center will also be displayed, that way you can get carrier and sidebands in one second and read modulation frequency etc.

Written From MY perspective with things I always look for. Same for deebees vertical etc.

You can also switch with one button click to the next harmonic and some more functions for alien civilizations.

Your frequency readout shows something like 106304567Hz which is hard to read. 106,304,567.0 Hz would suit me and most other folks better, though YMMV.

I'd rather have 'span' than starting and finishing frequencies, but that's just a personal preference and again, YMMV. Just a couple of observations, not trying to diminish your achievements here. :-)

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I think I understand the problem:

For a heavy accumulation of dust, I use a small air compressor and blow the dust so that it lands on the floor. I then vacuum the floor to remove the dust. I use the same method to clean my book shelves, equipment shelves, and workbench. It's MUCH easier to blow the dust to where it can be more easily removed, than to vacuum the dust in place. Hint: wear a dust mask and safety glasses.

I live in a forest full of squirrels. The chew on literally anything to sample how it tastes. I've grown a few fruit trees. The squirrels take exactly one bite out of every fruit eventually destroying the entire crop. They don't like eating the fruit, but that doesn't stop them from sampling every fruit on the tree. They also chew garden hoses, CAT5 cable, coaxial cable, telephone cable, Christmas tree light strings, and cardboard boxes stored outdoors. If this is what you call "intelligent", I suggest you revise your testing criteria.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Ah, I see,

There is something I think should be changed worldwide, that is Europeans use a dot where US uses a comma. so it Europe it would be 430.005.184 Hz but 999,124 here would be 999 + 124/1000

Here from the context if more than one dot it is clear where it is for input, but not for output.

Lemme see, been coding all day anyways, enters 430,005,184 in the frequency input field. Oops, the xforms GUI library removes the commas! Does not even allow me to type commas in these fields, because I use the integer type input field.

So, using the text input field it is simple to write a conversion routine, but it is locale dependent, the software has to know here it is used! So google to the rescue:

LOL now there you go.

Will have to use text input fields and setlocale().

But you are right, would be nice. On the to-do list.

Thank you.

It took me about 5 minutes to appreciate the benefits of autoranging. At the time, I was working on a very cluttered test bench. It was my first autoranging DMM, a Fluke 75 or something similar. My previous meter was a Fluke 8020A, which required considerable button pushing and a button decoder chart to operate.

The first think I noticed was that I could actually see the display because the entire front panel was not monopolized by a huge rotary switch and there was plenty of room for larger LCD digits.

My next observation was that I could easily switch ranges with one hand because I only needed to move the rotary switch one or two positions, not spin the switch through a large number of detents.

Unfortunately, it was downhill from there. There was no clear indication of what range the meter has auto selected. The decimal point was too small to see, and the AC/DC V/A and other indicators were tiny. This remained a problem until I discovered how to use the range lock button.

Permit me to suggest that you might be suffering from a latent addiction to analog meters. The problem is that the DMM display is digital and often does not resemble the pointer arc of analog instruments to which I suspect you are addicted. There are meters that do provide a pointer arc, which you might find more familiar and less uncomfortable:

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Sorry to hear about your fruit trees, but they're *still* smarter than I am in many respects.

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Just taking a closer look at the UNI-T DMM I use most draws my attention to 3 or 4 buttons I'd never really paid any attention to. I've no idea wtf they're for. I really must RTFM.

Well, I admit I still keep several high quality analogue meters and they still get used a fair bit. I have an AVO model 8 permanently monitoring the mains voltage, for example. It's nice not to have to worry about battery drain!

These are really neat! Even the best analogue meters put loading on test points and whilst a lot of service manuals provide 'loaded readings' for analogue meters such as the AVO 8, increasingly they no longer do and in due course, no doubt, this will cease altogether. Thanks, Jeff! :)

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You're welcome, Jan. And get yourself a decent C compiler while you're at it. There's a program called gcc that comes free with Linux. No fancy BS or GUIs, just a great little no-nonsense compiler. ;-)

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those may look somewhat analogue, but they're not. They won't have the upsides of a real analogue meter.

interesting

I missed out on buying the last crop of analogue meters that had FET buffered inputs with was it 10M impedance. Oh well :/

NT

Are you sure?

"Twirl a Squirrel Champion" The bird feeder is rechargeable battery powered: The squirrel only looks like it might be battery powered.

Can I assume that you're smart enough to let go when it's obvious you're not going to get a free lunch and before you reach orbital velocity?

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

World Famous Chef Pantje is back in full effect

I like the Amprobe AM-5xx series for handheld battery-operated DMMs, rugged and lot of nice features for not too much dough. Around $40 for the 510 or you can get the 530 for about $25 more if you need true RMS.

Also I think it's one of the lowest-priced DMM series that's CAT III and appears to actually have the appropriately sized and rated components inside and not China-BS.