Author Topic: µCurrent Probe - CMicrotek : Ultra-low current measurement tools  (Read 7870 times)

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Offline EEVblog

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No, it's not mine.
It seems they have trademarked the name "µCurrent Probe"
http://www.indiegogo.com/projects/cmicrotek-ultra-low-current-measurement-tools

Not sure how they could have researched this field and developed the product without knowing about my µCurrent? To use the same name is pretty silly and confusing.
 

Offline hli

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #1 on: February 27, 2014, 12:13:58 am »
Their spec sheet for the uCP100 claims a bandwidth of 3MHz, with a gain of 200 (5µV voltage drop to 1mV output for 1nA current).
I would guess they copied the µCurrent design with some enhancements (higher output voltage) and forgot to read about the limitations...
 

Offline SpectrHz

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #2 on: February 27, 2014, 01:03:59 am »
What in the world is with those perks? It looks like they are just clearing out their attic and using it as perks... Nat geo dvds?? Only 3 or so of the perks apply to the campaign, is it standard practice to do this for IGG? I've never done any crowdfunding except the uRuler so, I'm a bit confused.  :-//
My blog, Maker, Engineer, Physics girl

 http://spectrhz.wordpress.com/
 

Offline Sigmoid

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #3 on: February 27, 2014, 02:30:28 am »
What in the world is with those perks? It looks like they are just clearing out their attic and using it as perks... Nat geo dvds?? Only 3 or so of the perks apply to the campaign, is it standard practice to do this for IGG? I've never done any crowdfunding except the uRuler so, I'm a bit confused.  :-//
No it's not you. These perks are ridiculous, the entire campaign is incredibly unprofessional. I wouldn't pledge a penny to these people.
 

Offline Neganur

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #4 on: February 27, 2014, 04:56:39 am »
that video confused me, what is he trying to do again - save the world or promote a product?
 

Offline Sigmoid

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #5 on: February 27, 2014, 05:18:45 am »
that video confused me, what is he trying to do again - save the world or promote a product?
The whole thing sounds like the naive environmental activism crap we did with friends in elementary school. The whole thing is nonsequitur. The guy may have 30 years experience in bringing electronic devices to market, but he has the marketing savvy of a 6 year old.
 

Offline EEVblog

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #6 on: February 27, 2014, 09:15:00 am »
that video confused me, what is he trying to do again - save the world or promote a product?

I was pretty bamboozled too.
Looks like they took too many marketing pills at the Startup America course and have gotten all confused.
 

Offline pickle9000

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #7 on: February 27, 2014, 09:37:28 am »
Maybe he is trying to target an established customer base with a similar product.
 

Offline EEVblog

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #8 on: February 27, 2014, 09:40:26 am »
Maybe he is trying to target an established customer base with a similar product.

Well if he's knowingly doing that and deliberately using the same name, then that's a real dick move.
 

Online dr.diesel

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #9 on: February 27, 2014, 10:00:31 am »
Ha talks about the medical industry needing a low current measurement system to further their designs, specifically artificial hearts.  Like the medical industry is browsing Kickstarter in the search of T&M gear, ha ha ha,  :-DD   :-DD   :-DD.

Offline pickle9000

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #10 on: February 27, 2014, 10:09:26 am »
Here is his bio. Looks like a company just over a year old.

http://www.linkedin.com/in/mikelease

I can't think of any circumstance where he did not know of your product beforehand. At the very least he should say that he is not affiliated/connected to/with the Dave Jones ucurrent.

I like a good head to head product battle but not something that appears to be sneaky.
 

Offline EEVblog

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #11 on: February 27, 2014, 12:32:11 pm »
I can't think of any circumstance where he did not know of your product beforehand.

I just heard from the designer Mike, and he claims he had never heard of me (and presumably the µCurrent) before someone posted a comment of "nice rip-off of Dave Jones" on his campaign.
Well, ok, I'll take his word for it.
« Last Edit: February 27, 2014, 12:52:58 pm by EEVblog »
 

Offline Legit-Design

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #12 on: February 27, 2014, 12:48:23 pm »
Maybe he doesn't know EEVblog and Dave Jones are connected? It could happen.  ::)

Indiegogo + flexible funding = dodgy all the way
« Last Edit: February 27, 2014, 12:52:04 pm by Legit-Design »
 

Offline EEVblog

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #13 on: February 27, 2014, 12:57:46 pm »
Indiegogo + flexible funding = dodgy all the way

The comments are hidden too.
I'm not sure why anyone would contribute to these types of flexible campaigns, as you run the risk (even greater than normal) of the developers running out of money before they can deliver anything.

This is the µCurrent Probe PCB


I see 4.99ohm and 4.99K shunt resistors. But the chip numbers look to be rubbed off or photoshopped out.
« Last Edit: February 27, 2014, 01:00:16 pm by EEVblog »
 

Offline Stonent

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #14 on: February 27, 2014, 01:14:27 pm »
Ha talks about the medical industry needing a low current measurement system to further their designs, specifically artificial hearts.  Like the medical industry is browsing Kickstarter in the search of T&M gear, ha ha ha,  :-DD   :-DD   :-DD.

They didn't like Agilent's new name either.
The larger the government, the smaller the citizen.
 

Offline HackedFridgeMagnet

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #15 on: February 27, 2014, 02:02:41 pm »
From the photo:

On the analogue(US product) front end.

what are the devices with references LC1-4 ? are they single device LC filters perhaps? Anyone know.

Does it do two lots of current? Why 4 inputs. maybe different ranges?

Not important, just wondering.
« Last Edit: February 27, 2014, 02:05:26 pm by HackedFridgeMagnet »
 

Offline BravoV

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #16 on: February 27, 2014, 02:08:52 pm »
that video confused me, what is he trying to do again - save the world or promote a product?
The whole thing sounds like the naive environmental activism crap we did with friends in elementary school. The whole thing is nonsequitur. The guy may have 30 years experience in bringing electronic devices to market, but he has the marketing savvy of a 6 year old.

Actually not this guy to blame for the campaign, but the "other" guy guru I highlighted below ...  :palm:

Source -> http://www.cmicrotek.com/about.htm


Quote
Who we are

CMicrotek is a start-up company ... <snip> ...

Our management team is still being formed and includes:

A marketing guru with 30+ years experience who excels at mixing the tried and true marketing techniques with the brave new world of social media and digital marketing.

A former VP at one of the largest oscilloscope manufacturers in the world with nearly 30 years experience in the Test & Measurement industry
« Last Edit: February 27, 2014, 02:16:57 pm by BravoV »
 

Offline EEVblog

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #17 on: February 27, 2014, 03:48:13 pm »
From the screen shot:

It looks like two separate channels are being used with the two shunts, but in series (perhaps externally wired like that?) on the same current signal.
You can see that trace two is measuring the same signal as trace above it, but is allowed to go off full scale.
 

Offline pickle9000

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #18 on: February 27, 2014, 04:38:12 pm »
Regardless of the product, it could be a toaster for all I know. The real issue is that if you google ucurrent and are checking out this guy what will you find?  Assuming they are not out to deceive (as they say), they should inform anyone looking to invest. That should be done on the .com and the campaign page. I think that would be the very least they could do.
 

Offline hans

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #19 on: February 27, 2014, 09:32:57 pm »
Really confusing campaign. My understanding of low power electronics was that it enables battery powered equipment, not that they save the planet (in the end batteries are a necessary evil). If we want to save the earth from CO2 gasses, then we should probably all stop driving a non-electric cars and stop using coal or gas in power plants.

Moreover, I don't think much people will do a low-power optimization cycle for anything non-battery powered, unless there is a heat issue. However, heat issues are often resolved with better cooling.

The "power analyzer" looks like a very similar to a project I am working on: https://www.eevblog.com/forum/chat/what-are-u-working-on-right-now-%28electronics-related-and-with-picture-please%29/msg331101/#msg331101

Shunt is 10 ohms (0.1%). I use the AD8253 INA, which is programmable gain 1-1000x (per order of magnitude).
At 1000x gain I get 50nA/LSB. At 100x gain I get 0.5uA/LSB. The AD8253 has 4MHz -3dB bandwidth of 550kHz at G=100. The noise (because I forgot an anti-alias filter  :palm: ) is about 10LSBpp. So 16-bit / 10LSB = 12.7bits roughly usable bits.

INA gain error is typically 0.04%. As the shunt is 0.1%, and I have a resistor divider (0.1%) to connect the front-end to the A/D (which is a bit of a pity to throw away so much gain), I get roughly 0.24% DC accuracy.
Unfortunately the MCP3911 has a PGA gain accuracy of 4%, and it's auto-zero feature (which can't be turned off) screws the offset cal up every reset. So it has to go in Rev2.

However, it does work:

https://dl.dropboxusercontent.com/u/207647/PA/330k%20ohm.png
Connecting a 330k ohm resistor (3.3V rail) at 1000x gain over 10R shunt. Nice 50Hz pickup / body resistance. No filtering done. I still think this image is quite noisy.
100x gain is probably the most usable range.

https://dl.dropboxusercontent.com/u/207647/PA/Noisefloor gain 1000x.png
Noise "measurement" at 1000x gain. 0dB = FS(1300uA).

Not sure whether I should open source this project. :-/O


Anyway, I really wonder what kind of performance this probe/analyzer achieves. It says it has a dynamic range of 1:40000, which sounds to me 15+ bits of resolution, but at the same time the DC accuracy is 2.5% (order of magnitude worse than my power analyzer, or several orders of uCurrent Gold).

So 1:40000 is way overkill for an 8-bit or 12-bit scope resolution measurement, but at the same time measurements can be off by 2.5% for a multimeter. :-// Am I missing something?

The picture shown could be from a single low-ohm shunt, but with different gain front-ends. You can clearly see the noise at the microAmp graph, not so much on the mA chart. So as one clips you can view the other one for a large scale picture, and use the other for low-current measurements.
 

Offline EEVblog

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #20 on: February 27, 2014, 09:48:34 pm »
The picture shown could be from a single low-ohm shunt, but with different gain front-ends. You can clearly see the noise at the microAmp graph, not so much on the mA chart. So as one clips you can view the other one for a large scale picture, and use the other for low-current measurements.

That's how I do I think for such a logger. Overload recovery on the high gain amp would play a role, but if you sample both at once you can get a good overview of large dynamic range stuff.
You are still limited by the trade-off on the choice of sense resistor and usable gain though. I think the Mooshimeter tries to use a 24bit ADC, but ultimately only has 2uA resolution.
 

Offline hans

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Re: µCurrent Probe - CMicrotek : Ultra-low current measurement tools
« Reply #21 on: February 27, 2014, 10:41:50 pm »
Or possibly the second graph is "digital gain" (as in Camera digital gain vs optical gain) and only amplifies the bits, as the noise shown is clearly quantization noise.
Otherwise looking at a signal with 1:40000 dynamic range is kinda pointless on a monitor with 1080 height pixels.
Then the clipping an INA is not an usual use-case.

In a previous life I have built a logger like I previously described, with 2 INA's at different gains, and also multiple post-gains (all fixed). The software would decide which one to use. Problem: the A/D's in that system alone was 35 euro's, because all A/D's were simultaneously sampling. Since then (when I am building my own) I decided it's best to assume the guy who uses the logger, better knows how it works and how best to use it, and rely on 1 channel with range switching.

And then there always is the trade-off between current shunt. As shown, x1000 gain on a 10R shunt & viewing micro amps is right down in the noise. x100 gain is much more "usable".

Didn't the mooshimeter also try to make a huge dynamic range, by using few ranges with high resolution? Like 10A / 24-bit? Even if the ENOB is 20, the resolution is 9,5uA/LSB.
Possibly another thing to mention is sampling rates; the uPower samples at 250kHz (it says?), my 10uA test was at 12ksps, the mooshimeter probably isn't accurate to 20ENOB beyond a couple of 10's Hz.
« Last Edit: February 27, 2014, 10:44:21 pm by hans »
 


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