Author Topic: Open Source Multimeter  (Read 235676 times)

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Offline EEVblog

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Re: Open Source Multimeter
« Reply #75 on: July 04, 2011, 11:51:49 am »
That assumes the project creators have a realistic idea of costs.
I always wondered what happens with a kickstarter when the money raised ends up not covering costs due to unforseen issues...

Interesting question.
AFAIK, once the project reaches it's goal, the project automatically gets the money in the bank, with potentially no recourse for the donators if you don't deliver?
Surely it's happened, anyone know?

Dave.
 

Offline ruku

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Re: Open Source Multimeter
« Reply #76 on: July 04, 2011, 03:21:38 pm »
Wow, this thread has totally taken off. I had my reserves the other week when I looked at it, and thought... meh! Idealistic, not going to fly too far.

While I think that the "how will people buy this" thing might be an issue, I'd TOTALLY get involved in this project, if only to learn as much as I can!

Dave, I really think there'd be some merit to bringing in the forum members here to design a project together. As long as you can assign people to help moderate and finalize decisions (so we're not stuck in analysis paralysis forever), I think it'd totally be awesome to run the gamut of the engineering V and design something!
 

Offline KuchateK

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Re: Open Source Multimeter
« Reply #77 on: July 04, 2011, 06:00:44 pm »
Someone mentioned to make it bench multimeter. I think it would be much better idea.

You can use big components with loose PCB spacing and have it servicable at home. Proper input protection with nice blast shields can be made at home. You don't have to worry about AA or 9V batteries. Bench case is so big you can put there 12v ups battery and still would be portable.

For the display... please don't listen to Dave (no offence) ;)

Just put the biggest mono (no color!) graphical LCD screen with backlight. Then you can display single, dual, triple, quadruple or even more channels in different layouts. You can have graphs and bargraphs. Display ton of text for help and schematics how to connect probes. This will give ton of flexibility including different fonts, symbols and anything you can imagine.

Look how nice Agilent meters with OLED displays are. Or better. Check out Fluke 287 & 289!
http://www.fluke.com/fluke/usen/digital-multimeters/fluke-289.htm?PID=56061&trck=289specifications

By having dual 5 digit displays you will lock yourself to have stupid loops of "press to display channel #x". Then second display for menus... Its complicated even before it started... Lets drop that gazzilion year fixed display technology.

Edit: Dave did review of Fluke:
« Last Edit: July 04, 2011, 07:18:16 pm by KuchateK »
 

Offline ndictu

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Re: Open Source Multimeter
« Reply #78 on: July 04, 2011, 06:36:16 pm »
Someone mentioned to make it bench multimeter. I think it would be much better idea.

You can use big components with loose PCB spacing and have it servicable at home. Proper input protection with nice blast shields can be made at home. You don't have to worry about AA or 9V batteries. Bench case is so big you can put there 12v ups battery and still would be portable.

For the display... please don't listen to Dave (no offence) ;)

Just put the biggest mono (no color!) graphical LCD screen with backlight. Then you can display single, dual, triple, quadruple or even more channels in different layouts. You can have graphs and bargraphs. Display ton of text for help and schematics how to connect probes. This will give ton of flexibility including different fonts, symbols and anything you can imagine. Look how nice Agilent meters with OLED displays are.

I agree. Once you go for bench design there is no need to conserve power so just put whatever display there you can find and then you can do all sorts of stuff with it.

Also, since it's opensource it should be really easy to build at home. There can be a professional design with SMD parts and multilayer PCBs but also a bigger double-sided through hole one (since the schematic would be open I'm sure someone would redesign it). Everyone could either purchase a kit or make their own PCB, buy the parts, make changes to hardware and firmware and build their own custom version.
 

Offline KuchateK

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Re: Open Source Multimeter
« Reply #79 on: July 04, 2011, 08:45:18 pm »
I forgot to mention. Bench instrument cases are available off the shelf, so only front/back panels must be custom.

Today it may be easier to get color LCD, so we might be forced to swallow that extra power usage.
 

Offline Bored@Work

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Re: Open Source Multimeter
« Reply #80 on: July 04, 2011, 10:00:20 pm »
I forgot to mention. Bench instrument cases are available off the shelf

Many are. But interestingly I never found a source offering my favorite bench instrument form factor, complete with a handle and rubber bumpers 254 x 104 x (303 ... 375) mm^3 stackable. Companies like Agilent use them for ages for smaller instruments. E.g. http://www.home.agilent.com/agilent/product.jspx?nid=-536902257.536881980.00

If someone has a source for these specific enclosures I would be glad to hear of it.
« Last Edit: July 04, 2011, 10:04:06 pm by BoredAtWork »
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Offline Frant

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Re: Open Source Multimeter
« Reply #81 on: July 04, 2011, 10:39:26 pm »
Someone mentioned to make it bench multimeter. I think it would be much better idea.

Just put the biggest mono (no color!) graphical LCD screen with backlight. Then you can display single, dual, triple, quadruple or even more channels in different layouts. You can have graphs and bargraphs. Display ton of text for help and schematics how to connect probes. This will give ton of flexibility including different fonts, symbols and anything you can imagine.

I mentioned a bench meter, but I also said it could be a modular system. It's an open source project and people would like to make different modules to suit their needs, to add channels, to upgrade existing modules and to learn something in the process. It should be an open hardware and software platform rather than a fixed hardware design. Professional modular instrument platforms exist, and I mentioned two: PXI and Agilent USB Modular Instruments. However, this open source project should be much cheaper to build and also simple enough to be accepted by hobbyists.

As for the display, it can be a part of an user interface module, so that one can choose from several options or not to have it at all. It's a bench instrument and there would probably be a PC on the same bench, with much more user interface resources.

USB is a good choice because it is fast and it provides up to 500 mA for the instrument, so the mains power supply may not be needed. I'm not so enthusiastic about wireless things in situations where they are not absolutely necessary. They are inherently less reliable, they add complexity to the system and always involve batteries which must be taken care of. However, I had a surprisingly good experience with a SENA Parani-ESD200 Bluetooth-serial module, used with a Bluetooth/USB adapter connected to a PC. Once set properly, it worked flawlessly for months. It was actually used to isolate a sensitive signal acquisition system from a PC.
 

Offline ndictu

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Re: Open Source Multimeter
« Reply #82 on: July 04, 2011, 11:00:55 pm »
I mentioned a bench meter, but I also said it could be a modular system. It's an open source project and people would like to make different modules to suit their needs, to add channels, to upgrade existing modules and to learn something in the process. It should be an open hardware and software platform rather than a fixed hardware design. Professional modular instrument platforms exist, and I mentioned two: PXI and Agilent USB Modular Instruments. However, this open source project should be much cheaper to build and also simple enough to be accepted by hobbyists.

As for the display, it can be a part of an user interface module, so that one can choose from several options or not to have it at all. It's a bench instrument and there would probably be a PC on the same bench, with much more user interface resources.

Exactly. For example, I would like to start with a simple two channel input interface, with V/ohm and current, and an USB interface with the display/data logging on the PC. Then later get some display, add some button interface and have a more stand-alone unit. Someone might want to add a big flash for data logging, someone will just leave the PC running for that. Someone wants a lot of current inputs, someone will put on 10 thermocouple inputs.

Something like a modular reference design and everyone can make little changes, pick what they like, ignore the rest or add it later.
 

Offline EEVblog

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Re: Open Source Multimeter
« Reply #83 on: July 05, 2011, 02:50:07 am »
You can use big components with loose PCB spacing and have it servicable at home. Proper input protection with nice blast shields can be made at home. You don't have to worry about AA or 9V batteries. Bench case is so big you can put there 12v ups battery and still would be portable.

For the display... please don't listen to Dave (no offence) ;)

Just put the biggest mono (no color!) graphical LCD screen with backlight. Then you can display single, dual, triple, quadruple or even more channels in different layouts. You can have graphs and bargraphs. Display ton of text for help and schematics how to connect probes. This will give ton of flexibility including different fonts, symbols and anything you can imagine. Look how nice Agilent meters with OLED displays are.

I agree. Once you go for bench design there is no need to conserve power so just put whatever display there you can find and then you can do all sorts of stuff with it.
[/quote]

I disagree on not conserving battery power. I'd still want a bench meter say D cell powered. (please, forget this rechargable rubbish!)
With D cells you could possibly create a killer battery life logging meter, opening up new niche markets.

7 segment LCD's still kill dot matrix for viewability, sorry, no contest. Having both is not such a stupid idea, and can help when you go into long term data log battery mode to conserve power yet still display status.

Dave.
 

Offline thmjpr

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Re: Open Source Multimeter
« Reply #84 on: July 05, 2011, 04:03:52 am »
Interesting question.
AFAIK, once the project reaches it's goal, the project automatically gets the money in the bank, with potentially no recourse for the donators if you don't deliver?
Surely it's happened, anyone know?

Dave.

Quote
There is no guarantee that people that post projects on Kickstarter will deliver on their projects or use the money to do their projects. Kickstarter advises sponsors to use their own judgment on supporting a project. They also warn project leaders that they could be liable for legal damages from sponsors for failure to deliver on promises. In May 2011 a New York University film student raised $1,726 to make a film, but plagiarized the French film Replay instead.
from http://en.wikipedia.org/wiki/Kickstarter
 

Offline fchk

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Re: Open Source Multimeter
« Reply #85 on: July 05, 2011, 09:49:30 am »
I've just seen the video and really like the idea of multiple inputs.

However, I'm a very big fan of the UNIX philosophy: have small, single-purpose tools that do their things right. The video suggests some kind of feature-itis, which definitely will make the whole thing more expensive, but not neccessarily better. If I need temperatures, I'll get a thermometer. If I need to measure impedances, I take a decent RCL meter, which only does this single task, but is way superior in terms of accuracy compared to most general purpose meters. Having a single-purpose Volts-Amps-Watts-Wh meter would make the input circuits much easier and propably more precise.

One or two CV/CC outputs might make sense for some tasks, but this could easily be added as an second step.

For the display nothing beats VFD's in terms of readability. I really like my Agilent 34401A
 

Offline ndictu

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Re: Open Source Multimeter
« Reply #86 on: July 05, 2011, 11:55:47 am »
7 segment LCD's still kill dot matrix for viewability, sorry, no contest. Having both is not such a stupid idea, and can help when you go into long term data log battery mode to conserve power yet still display status.

Well, once again, with the bench design

- you have much more space, so why not. You could have one, two or three standard 7segments and one dotmatrix for menus, or extra measurements if you don't have enough 7segments.

- everyone can build their own version. Someone prefers 7segments, someone wants a big dotmatrix.

About the batteries, do you mean a battery powered or as a backup? Maybe while running on mains you could be using everything but when you disconnect it (or power goes out) it'll try to conserve power by switching displays off?
 

Offline Bloch

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Re: Open Source Multimeter
« Reply #87 on: July 05, 2011, 07:27:46 pm »
Many are. But interestingly I never found a source offering my favorite bench instrument form factor, complete with a handle and rubber bumpers 254 x 104 x (303 ... 375) mm^3 stackable.

That about Bopla BOTEGO

240,98 mm * ( 49,96 mm, 65,20 mm, 80,44 mm) * 196,9 mm
307,35 mm * ( 49,96 mm, 65,20 mm, 80,44 mm) * 196,9 mm

stackable , handle  as option
and a  angled operating front is an option

http://www.bopla.de/en/product-catalog/enclosure-technology/product-category/botego-6.html


 

Offline Bloch

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Re: Open Source Multimeter
« Reply #88 on: July 05, 2011, 07:50:02 pm »
With D cells you could possibly create a killer battery life logging meter, opening up new niche markets.

Now that is some thing I like  ;D

I did a quick look in a catalog Varta batteries

AAA HIGH ENERGY  1,1Ah LR03 1200mAh
AA  HIGH ENERGY  2,6Ah LR06 2930mAh
C   HIGH ENERGY  7,8Ah LR14 7800mAh
D   HIGH ENERGY 16,5Ah LR20 16500mAh


No. Now I think about it. It is just to much power  :)




 

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Re: Open Source Multimeter
« Reply #89 on: July 05, 2011, 10:12:34 pm »
For the display nothing beats VFD's in terms of readability. I really like my Agilent 34401A
7-segment LED comes close, often superior since the digits tend to be larger. Of course they don't do text well. LCD sucks for bench use in my opinion, VFD and LED are just superior for displaying numbers if you don't care about power use. Viewing angle is important if you don't want to move equipment all the time.
 

Offline Kiriakos-GR

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Re: Open Source Multimeter
« Reply #90 on: July 06, 2011, 12:07:03 am »
so please stop posting nonsense like all this...

Forum rule No1 ,  never say to others what to say or not.
If you can not handle the conversation, ignore it.   

Just a friendly advice.
« Last Edit: July 06, 2011, 12:10:50 am by Kiriakos-GR »
 

Offline EEVblog

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Re: Open Source Multimeter
« Reply #91 on: July 06, 2011, 12:14:43 am »
Quickest sketch took me 20 min...

Wow, Awesome!

Dave.
 

Offline Zad

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Re: Open Source Multimeter
« Reply #92 on: July 06, 2011, 01:10:52 am »
Blimey!!!!! I don't agree with ANYTHING that you've posted, not a single point! What a lot of rubbish! I am not going to spend any more time on this, but just to say that a decent prototype case for this type of enclosure (about 5 units) will take for about $300, so please stop posting nonsense like all this...

Robust peer review is the basis of all sound science, but denial without explanation is simply Trolling, and is the curse of many forums around the Internet. Anyone can say "No, you are wrong", but it takes skill and intelligence to say why.

If you care to read my post instead of jumping to conclusions, you will notice I talk about tooling (i.e. for production) not 1-off prototype enclosures. Prototypes can be milled from solid or built up using desktop prototyping methods, this is clearly not viable for production quantities.



Anyway, so I don't create an entirely negative post, 256x64 monochrome OLED displays are getting quite cheap now. Crystalfontz retail them in 1000+ qty for $23:48 ($51:48 1-off). They have on-board controllers and 16 level grey-scale.
http://www.crystalfontz.com/product/CFAL25664AYB1

If the designer should choose to go with a bench instrument (or a big battery) Crystalfontz also do 320x240xRGB TFT with integrated controller for $18:82 in 1000+ qty. ($53.72 in 1-off) It also has a touch screen option.
http://www.crystalfontz.com/product/CFAF320240F-035T

That seems phenomenally cheap for a QVGA including controller, where is the gotcha? I designed some bench test equipment about 7-8 years ago, and the display+controller came in at around £250 (100-ish qty) for a similar QVGA.


Offline Tony R

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Re: Open Source Multimeter
« Reply #93 on: July 06, 2011, 02:31:34 am »

Linus Torvalds never made hardware. He did not have to care about how much something cost, or how expensive or difficult it was to manufacture, or if you could get the parts etc.

Very true; however, and perhaps I should have stated it more clearly, if someone wants to make their own DMM and publish everything as to how they did it, and maybe someone else will take that design and improve upon it, why not do it? Maybe it wont be very popular, but who says it has to be?

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Offline Bloch

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Re: Open Source Multimeter
« Reply #94 on: July 06, 2011, 05:30:44 am »
Display.

If it is a "long time" product. I mean a  product that will be interesting many years. Then I dont like LCD + oled .......

I think it will be a bad choice to use a part that will not be on sale in like 3 years.

But with Led´s I dont think they will go away for the next 10 years.


Iphone app.

This is also a bad choice.

It is a "lock in" Can the app run i the old Iphone or the next one. And that about the android users ?

No the only proper thing to do is a web server. As I dont thing they are going to change the internet for the next 10 years ! Not like the 6 month for phones.

 

Offline FreeThinker

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Re: Open Source Multimeter
« Reply #95 on: July 06, 2011, 09:02:54 am »
Talk about hijacking a thread! The OP asked for comments on HIS kickstarter handheld meter, now we are talking (bickering?) about a non existing bench meter project! Chill out Peebs :)
Machines were mice and Men were lions once upon a time, but now that it's the opposite it's twice upon a time.
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Offline joegtp

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Re: Open Source Multimeter
« Reply #96 on: July 06, 2011, 12:17:06 pm »
This seems like a repeat of another thread a while back -- https://www.eevblog.com/forum/index.php?topic=173.0

Open source projects just don't start like this. It's going to take one maybe two people to be the leads and just do it. And by "do it" I mean do 90% of the initial work. You are never going to get anywhere by committee. If the decision is made to use LEDs instead of a graphical display are you still going to be motivated enough to work on the project? What about handheld vs benchtop? USB vs Wireless? Battery powered vs plugged in? There are way too many decision points and anyone of those will probably lessen your motivation to work on the project.

I love the idea of having an open source electronics bench: power supply, DMM, logic analyzer, etc. But this is not how it's going to happen.
 

Offline Zad

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Re: Open Source Multimeter
« Reply #97 on: July 07, 2011, 02:09:14 am »
Yes, the larger a group gets, the less likely it is to go anywhere. Linux was 1 man (plus GNU of course) and the ARM was just 2 people with no money and no resources. Similarly, the Mars rovers team had nothing for development and a very difficult deadline to hit. 

The important thing is to set realistic goals and get on with it. If you get diverted with 4 isolated channels, LCR/ESR and so on, then it will never get anywhere. Publish your results when you get a good design, and then if other people want to make their own machine then that is up to them.

Offline EEVblog

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Re: Open Source Multimeter
« Reply #98 on: July 07, 2011, 02:46:39 am »
I've said it before. I'm convinced the optimum number of people to work on a project like this and make the decisions rounds down to 1, almost always.

Dave.
 

Offline Mechatrommer

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Re: Open Source Multimeter
« Reply #99 on: July 07, 2011, 04:24:07 am »
well 3x, near 3K view in a week (and 7 pages) hit on "Open Source" topic! what do we have got here?
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 


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