Bench multimeter?

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Is the VC8045 worth the price?
http://www.ldbmart.com/betydimuv...

Why is it so big?

It's 10 x 9 x 3 inches. Or if prefer, 260 x 220 x 82 mm.

What's in there that takes so much room? I would be more inclined to buy it if it was half the size.

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Quote:
What's in there that takes so much room?
Mostly open space :)
Bench-equipment is always larger than the handheld versions of it. So if you're looking for a mor compact solution, go for a handheld.

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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The VC8045 is cheap and claims a lot better specs than any handheld I've found for under $300. It has a 4 1/2 digit display and claims 0.05% accuracy.

All the handhelds are 3 3/4 digits and claim 0.5% accuracy, even the $95 ones. I can get that in a $35 Mastech. The Mastechs are not quite as accurate as the specs claim, but for all I know the BK precision meter isn't either. Furthermore the error changes with battery voltage with the handhelds I have.

If I want to measure in the 2 - 4 volt range with an accuracy of +- 1 mv, I have to calibrate my handheld with a precision reference voltage, and then correct all the readings. It would be damned nice if I had a meter that would tell me the voltage down to the millivolt, without having to correct the reading.

My two older DMMs are powered with a 9 volt battery. I need to open up the case and let all the guts hang out to change the battery. There is no auto poweroff, so I need to change this expensive battery often.

My newest DMM uses 3 AAA cells and has an easy to open battery compartment. I use low self discharge NiMH cells. NiMH cells don't change their voltage much during discharge, but the error still changes over time.

The more I look at the VC8045, the more I get suspicious. One place apparently sells it for $110, another place sells the VC8045-II, with the same spec. for $55. There doesn't seem to be a datasheet available anywhere, but the specs are shown on the web pages.

One trick I did with one of my DMMs was to power it from a wall wart and a regulated power supply. Because the supply voltage doesn't change, neither does the error. Now I'm thinking I should try experimenting with an adjustable power supply. If the error is a function of the supply voltage, maybe I could find a supply voltage where the error is zero. (+ - 1 mv).

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Smart thinking Steve ! Worth a try, that powersupply trick.

I wasn't aware that you were looking for a very high accuray multimeter. The pricing you mention is indeed very moderate for specs like that. If the specs are true, you've got a bargain. But frankly, I don't think that a MM with those specs can be produced for that price. For high quality I'd go for Fluke, but that's a different price-range indeed.

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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The VC8045 is from victor electronics. They should have a datasheet. Lets just say, victor electronics is not known for high-end multimeters.

Regarding 4 1/2 handhelds, there are several on the market, for example UNI-T UT70D or several Fluke.

A good alternative would be a used Fluke bench multimeter plus a recalibration.

Stealing Proteus doesn't make you an engineer.

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You might want to look at EBAY for a nice meter. Getting it calibrated will not cost much either.

Times be tight here in New York, me friend. Better to look for a good used unit and calibrate it to save a few pennies!

Jim

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The 0.05% accuracy is probably mixed up with with 0.05% resolution, which would be about right for a 4.5 digit reading.

p.s. you usually wand much more than 0.05% accuray, even 99% accurate is not very good.

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I think an older Agilent or Fluke benchtop meter from Ebay will be a better deal. You get what you pay for with this stuff. Or in the case of used equipment - what somebody else paid for 10 years ago :)

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Kleinstein wrote:
The 0.05% accuracy is probably mixed up with with 0.05% resolution, which would be about right for a 4.5 digit reading.

p.s. you usually wand much more than 0.05% accuray, even 99% accurate is not very good.

Well yes and no. I too am suspicious. I may not have stated it correctly, but they do claim high accuracy. Just to set the record straight, a B&K $95 handheld meter gives the DCV accuracy as:

+- (0.5% + 2 digits)

The VC8045 gives it's DCV accuracy as:

+- (0.05% + 3)

If it is half as good as claimed, it would be a bargain.

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Well that UT-70D looks good, but it doesn't seem to be available in the U.S. Maplin sells it for 89.99 pounds which translates to $137.15 according to one website. That's more than I want to pay, but I will consider it. It has the same high accuracy that the VC8045 claims to have. Shipping might be expensive, if Maplin even ships to here.

There ought to be something like this available in the U.S. but so far I haven't found it. I could spend a week trying to track down a new Fluke that suits my budget and needs. I checked out the Fluke 289 handheld. Great specs. Twice the accuracy of the VC8045, (+- 0.025%) but Digikey wants $545 for it. I'll check eBay later.

So come on guys. Won't somebody buy the VC8045 for $55, and give the rest of us a report? :)

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Probably nobody else is interested, but I'll finish this topic anyway.

I think I found the multimeter of my dreams. The Mastech benchtop MS8040 has high precision (22000 count), RS232, allegedly high accuracy, and relatively low cost. I've had good luck with Mastech and CircuitSpecialists.com so I wouldn't hesitate to buy it once I've convinced myself I'd be better off spending my money on this instead of mundane items like food, clothing and shelter.

http://circuitspecialists.com/pr...

I would have probably bought it already but apparently Mastech has an even better one. The handheld MS8218 has 50000 counts. This handheld would take up less space on my bench. I guess they call the big ones benchtops because they would cover the entire top of my bench. :) These handlelds are only available from an unknown someone in Hong Kong, and I'd have to make my own "plug in the wall" power supply for it. Neither Mastech has a manual available, although CircuitSpecialists has somehow come up with a calibration procedure for the benchtop.

http://www.gsmserver.com/shop/eq...

I've decided if I do buy another multimeter is will have a communications port to connect to a PC. Whether or not it has a procedure for calibrating and adjusting the reading (and the above benchtop apparently does), the PC can do it for me, and log the results too.

I tested my old MAS-345 and found the reading does not change with changes in power supply voltage. I guess that's good news. I also rediscover the long neglected RS232 port. I now have it hooked to my PC, and the PC makes the error correction for me.

I looked at a bunch of Flukes. Many of them are high accuracy. If a used one can be bought cheaply on eBay, that would be a good deal. They don't appeal to me though. None of the high accuracy ones have a communications port to hook to a PC. The handhelds use a complicated automated procedure to calibrate and adjust all the many ranges. It requires very expensive equipment, or must be sent to someone else for calibration.

The old Fluke 8050A bench supply can be bought cheap and could be a good deal. No communications port though. Strangely the calibration manual doesn't mention how to calibrate and adjust the 20 volt DC range, although it seems to explain all the other ranges. The 20 volt range is precisely the range I would be using.

Last Edited: Tue. Jun 2, 2009 - 10:30 PM
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Quote:
Probably nobody else is interested, but I'll finish this topic anyway.

Sure I am interested ! And most likely fellow-freaks I guess ...
Thanks for sharing the results of your quest.

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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I've had this for a while, three years maybe, still looking for a manual on this.

I have not found a way to let the background light stay on any longer than the 10 seconds or so. Why is there an auto-off feature on this on a benchtop meter anyways? It even auto-offs in some time, not predefined, even while I'm measuring, very strange. Found no way to turn either of these functions off.

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Model MASTECH MS8218 automatic power off do not work, it have to be switched off from button or it eats your batteries (takes about 4 months, and batteries are empty).

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Rereading the thread:

steve17 wrote:
If I want to measure in the 2 - 4 volt range with an accuracy of +- 1 mv,

This multimeter has to be set at least to 20V range to measure the voltage range you specified. Then the error is bound with +-0,05% reading +3digits). As you can see the last digit has a "1mV" weight, which clearly shows this is/was not a multimeter for you.

No RSTDISBL, no fun!

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steve17 wrote:
Is the VC8045 worth the price?
http://www.ldbmart.com/betydimuv...

Why is it so big?

It's 10 x 9 x 3 inches. Or if prefer, 260 x 220 x 82 mm.

What's in there that takes so much room? I would be more inclined to buy it if it was half the size.


In America they say: "bigger is better".
And: "There ain' t no substitute for cubic inches".

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I too have been looking at Mastech on gsmserver shopfront.

This si the unit I thought was pretty good value

http://gsmserver.com/shop/equipm...

Sadly it is not available presently.

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I see my thread has been resurrected from the dead.

I never did buy any of these mysterious bench multimeters. I figured if they were good, people would have bought them and there would be reviews and manuals too.

I eventually bought a used Fluke 87 III handheld on eBay for $120. It measures voltages accurately to the millivolt.

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Quote:
It measures voltages accurately to the millivolt.

I do not think so.
Fluke 87 UserManual wrote:
±(0.1% + 1)

It gives +-5mV spread at the range you specified, when calibrated properly.

No RSTDISBL, no fun!

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Et tu Brute?

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Brutte wrote:
I do not think so.
Fluke 87 UserManual wrote:
±(0.1% + 1)

It gives +-5mV spread at the range you specified, when calibrated properly.
So who you gonna believe, me or some lousy manual. ;) You do have a point there, but I don't bother with manuals. ;) I look for empirical evidence.

I have 4 voltage references that allegedly are accurate +/- 1 millivolt. They are nominally 1.024, 1.200, 1.800 and 2.500 volts.

When I measure them with the Fluke, here is what I see. What do you think?
.

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One more.
.

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Quote:
What do you think?

I think the manufacturer knows what components are placed inside. I can show you same pictures with a 4$ DVM and still that does not prove it is a 1mV accurate device. Battery voltage, humidity or temperature variations influence.

Did you calibrate it with your references before taking pictures? :)

No RSTDISBL, no fun!

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Just to be clear, I've never calibrated it. As far as I know, it costs as much to calibrate it as it does to buy another used one.

I agree that these readings are so good it's spooky. But it's real. No photoshop either. Maybe the Fluke is reading the markings on the chips. ;)

The first three reference voltages had been powered on for days. The readings were rock solid. I thought they would be because I have checked them before. The 2.500 reference is not normally powered on. When I first powered it on, the display flickered between 2.499 and 2.500. After a few minutes it stabilized at 2.500.

The Fluke doesn't seem to need a warmup. I've never noticed the display changing after power up.

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steve17 wrote:
As far as I know, it costs as much to calibrate it as it does to buy another used one.
Maybe.
http://www.tyrolab.com/

"Dare to be naïve." - Buckminster Fuller

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Maybe these pictures will help convince the sceptics. On the lower right of the PCB are two voltage reference chips. An ISL60002BIH310Z and an LM4132AMF-1.8. FOr the purposes of this picture I'm powering them with 2 AA cells. There is nobody behind the curtain. ;)
.

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Here is the specs from the owners manual for the 87 III. Copy/paste changed the format a bit.

Table 13. DC Voltage, Resistance, and Conductance Function Specifications
Accuracy1
Function Range Resolution Model 87

4.000 V
40.00 V
400.0 V
1000 V

0.001 V
0.01 V
0.1 V
1 V

±(0.05% + 1)
±(0.05% + 1)
±(0.05% + 1)
±(0.05% + 1)

http://www.fluke.com/Fluke/usen/Support/Manuals/default.htm?ProductId=56134

I spent the last 2 years in the Navy (72-74) working in a cal lab. The long term stability and accuracy of even the tube type Fluke differential voltmeters was amazing. As a result of that experience I decided that any meter I had to rely on would be a Fluke. I have 2 8842A's and 1 87.

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Look.. I know if it works it's a fluke... and I can accept that there is nobody behind the curtain... but do the hands ever leave the wrists?

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Ok, it is Fluke 87 rev. III and the specification detail I gave was for Fluke 87 rev I, I guess(no information about revision was mentioned).
Now, taking revision III into consideration that error is still not bounded within +-1mV on a 4V range you specified! Again, even Fluke 87 rev. III is/was not a multimeter for you.
I really appreciate your experience guys, but even when you calibrate or test 30 sets of Fluke's 87 rev.III that will not make them DVMs with a +-1mV error bounding at this range, and within conditions specified by the manufacturer. Firstly, because of the LCD construction which cannot present data with error lower than +-0,5mV (discretization error), and secondly, because of the components used.
Why don't you want to trust engineers from Fluke? If they say this is a +-(0,05%+1) multimeter and it meets the specification within 1 or 2 years from calibration, that is what they mean. That is, you can have a +-3mV error under these conditions and 4V range. Or a +-2mV error on a 2V range.

Still, that accuracy is impressive and well beyond my (or typical) requirements.

The cheapest (3,5digits) DVMs (3-4$) have error at +-(0,5% of reading +2digits) level within 1 year from calibration. On 2V range that gives +-12mV error.
As a rule of thumb one can assume that to halve the error you need to double the price (neglecting LCD size, auto-range, make or other RMS goodies). That is, the cheapest "Noname 830B" is about 2^(12mV/2mV)=64 times cheaper than Fluke 87 rev.III. So Fluke rev. III is about 250$+goodies. And still the DVM with a +-1mV error needs to cost about 128 times as much as "Noname 830B", or twice the price of Fluke, over 500$ :) If you pay less than that, then it is a good deal.

No RSTDISBL, no fun!

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Actually, Steves' first mention of the Fluke stated the rev III, and the posted pics show the rev III on the meter very clearly.
You are correct about them not having a stated accuracy of 1 mv on the 4 volt range. In my own personal experience, the typical accuracy and stability of Fluke meters IS better than spec, but with any individual meter you never really know for sure unless you have a known reference.

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RickB wrote:
Actually, Steves' first mention of the Fluke stated the rev III, and the posted pics show the rev III on the meter very clearly.

Yes, I know. As mentioned, I blindly assumed there is only one Fluke 87, while there are several types with different spec! Sorry again for the confusion :) .
steve17 wrote:
Maybe these pictures will help convince the sceptics.

Are you talking about me :?: But I do believe you and your experiment. But this does not prove it is a (0,0125%+1digit) multimeter, which would be a requirement for Fluke 87 to meet your expectations. Perhaps Fluke 87 rev. IX will do :wink:

No RSTDISBL, no fun!