CurrentRanger vs uCurrent Gold

[1anX]

Looks like Dave has new competition in this micro current measurement device. It looks extremely similar to Dave's device, but is indeed different and looks like a very good variation to a theme!

https://lowpowerlab.com/2018/09/26/currentranger-auto-ranging-current-meter/

https://youtu.be/uFel6cXnl_4

[1anX]

The CurrentRanger's ability to auto-range sets it apart from the uCurrent Gold. It also features hackable firmware and many useful options such as Bluetooth and plug in display!

Has anyone on this forum got one?

I'm tempted to buy one and am curious if anyone can let me know of their experience in getting one shipped to Oz.

[Gyro]

Aside question, but one with a purpose - what is the lowest voltage range and resolution of your DMM?


EDIT: To clarify. In my opinion, don't waste your money on any of them (I see the one you listed is $120!). They all have the same fundamental flaw - only 3 non-optimal, shunt resistor values.

Having simple 1mV / nA / uA / mA conversion factor is all very simple and convenient, but it results in huge gaps in the shunt resistor values (10mR, 10R, 10k). It's far better to use the optimal shunt resistor for your needs and do the maths (eg. a 1mV / 10uA range).

If your DMM has decent mV (probably 100uV on 3 1/2 digit) resolution. Then go out and buy a set of resistors 1 decade apart, eg. 10mR, 100mR, 1R, 10R, 100R, 1k, 10k, as you need and of whatever tolerance you see fit. Either use them as-is or mount them on a board with whatever convenient connectors you wish.

Connect whichever resistor that best meets your anticipated current and acceptable voltage burden in series with the load. Measure the voltage (mVs) directly across the resistor (to avoid connection resistances). And calculate the resulting current.

One other thing, beware of using shunt resistors above 10k. The load resistance of the meter (probably 10M) becomes significant. At 10k it only results in 0.1% error but at 100k, its 1% etc. You can do it, just take the meter loading into account.

[MadTux]

For that price I take a Keithley electrometer/sourcemeter anytime, the oldish ones, like Keithley 610C or 616 are available on ebay for similar price. And they measure current down to picoamps/femptoamps without any shunt drop.

Digital ones, such a K617 also have autorange, but usually cost a little more. For around $400 you can get a Keithley 236 sourcemeter and power the device from it directly, while measuring voltage and current down to mV/pA.

These things would be nice, if available for like $5 from china,  but $120, mhhhh no.

[alex-sh]

The CurrentRanger's ability to auto-range sets it apart from the uCurrent Gold. It also features hackable firmware and many useful options such as Bluetooth and plug in display!

Has anyone on this forum got one?

I'm tempted to buy one and am curious if anyone can let me know of their experience in getting one shipped to Oz.

I got one. uCurrent Gold is not for sale 
Given that I am measuring sleeping current (30nA-5uA) and wake-up (18mA) current, this is exactly what I need.
Cannot recommend it more.

Taking into account its price, I do not think it is a competitor to Dave's uCurrent Gold though.

[alex-sh]

For that price I take a Keithley electrometer/sourcemeter anytime, the oldish ones, like Keithley 610C or 616 are available on ebay for similar price. And they measure current down to picoamps/femptoamps without any shunt drop.

Digital ones, such a K617 also have autorange, but usually cost a little more. For around $400 you can get a Keithley 236 sourcemeter and power the device from it directly, while measuring voltage and current down to mV/pA.

These things would be nice, if available for like $5 from china,  but $120, mhhhh no.

I think you are comparing apples with pears. The size and weight of Keithley 610C or 616??? It is an old huge analogue meter.
Keithley 617 is nice, but currently the lowest price on eBay is $950. Keithley 236 is even more expensive. How is this comparable with a small
device measuring nA for $120? For what its worth, this is a brilliant device. Hackable, very portable and very accurate. Autoranging is handy measuring sleeping current.
And the noise in nA is much smaller than in uCurrent Gold (Dave, you have got to do something about it in the next rev).

[exe]

+1 here for size and price concerns. I wanted to buy quite a few boat anchors, but my bench is just an office desk. Desk real estate is not for free .

Prices for second-hand equipment are also insane (on ebay). I understand that old test equipment is cool, but when sellers ask for Keithley 2000 about as much as for new DMM6500... Reasonable deals require a lot of patience nowadays.

[1anX]

A new video comparing the CurrentRanger to the uCurrent Gold in measuring supply and sleep current to an ESP32. A really well done comparison and it looks like the uCurrent Gold has been displaced by the newer challenger in these test conditions.

[Gyro]

Damn, despite my previous disparaging comments on cost and range limitations, I'm warming to it now. 

The autoranging is obviously fast enough to avoid brownouts. I hadn't realized it offered the other stuff like display and datalogging support too. Open source firmware to tweak it to your needs too.  There's obviously a significant amount of design work gone into it.

It looks as if it certainly justifies the price differential in terms of increased function and BOM cost (although from a very high starting point). It would still be nice to see more current ranges for accuracy but I can see that it fits the intended target active/sleep current monitoring application very well.

[joeyjoejoe]

Would either of these beat out even relatively high-end bench meters? SDM3055? DM3058E?

[LapTop006]

A new video comparing the CurrentRanger to the uCurrent Gold in measuring supply and sleep current to an ESP32. A really well done comparison and it looks like the uCurrent Gold has been displaced by the newer challenger in these test conditions.

One of these days I'll get my hands on a Keysight N6705, but they're so expensive. Another option in the Keysight space is the N2820A probe.

[Marco]

For that price I take a Keithley electrometer/sourcemeter anytime, the oldish ones, like Keithley 610C or 616 are available on ebay for similar price. And they measure current down to picoamps/femptoamps without any shunt drop.

Lose some max burden voltage, add some DC offset burden voltage ... transimpedance mode is not perfect. Also autoranging from transimpedance at low currents to shunt at high currents is complex and for the Keithley picoammeters not actually done, they peak at 20 mA. Range switching is also slow, 10s to 100s of ms.

If you want to measure current consumption for a circuit at high resolution in time and with wide dynamic range, this is pretty good.

[Electro Fan]

Would either of these beat out even relatively high-end bench meters? SDM3055? DM3058E?

Looking at uCurrent Gold and Current Ranger, or other similar "cost-effective" solutions for measuring low current .....

Tried using the search (since someone will often ask "have you tried searching"?).  Answer is of course yes (almost always do) but here's some proof

Anyway....

Saw this question posted by joeyjoejoe.... and would be interested in knowing the answer.

Anyone have an answer or any thoughts on his question......?  Thx

[SilverSolder]

Would either of these beat out even relatively high-end bench meters? SDM3055? DM3058E?

Looking at uCurrent Gold and Current Ranger, or other similar "cost-effective" solutions for measuring low current .....

Tried using the search (since someone will often ask "have you tried searching"?).  Answer is of course yes (almost always do) but here's some proof

Anyway....

Saw this question posted by joeyjoejoe.... and would be interested in knowing the answer.

Anyone have an answer or any thoughts on his question......?  Thx

Even high end meters don't typically have the low burden voltages (low shunt resistance) like you find in the uCurrent et al.   Furthermore, using your scope on a shunt resistor has the same problem:  the shunt has to have a high enough resistance to give a useful reading on the scope.   So the uCurrent type device solves a need even if you have a high end meter.

[Electro Fan]

Would either of these beat out even relatively high-end bench meters? SDM3055? DM3058E?

Looking at uCurrent Gold and Current Ranger, or other similar "cost-effective" solutions for measuring low current .....

Tried using the search (since someone will often ask "have you tried searching"?).  Answer is of course yes (almost always do) but here's some proof

Anyway....

Saw this question posted by joeyjoejoe.... and would be interested in knowing the answer.

Anyone have an answer or any thoughts on his question......?  Thx

Even high end meters don't typically have the low burden voltages (low shunt resistance) like you find in the uCurrent et al.   Furthermore, using your scope on a shunt resistor has the same problem:  the shunt has to have a high enough resistance to give a useful reading on the scope.   So the uCurrent type device solves a need even if you have a high end meter.

Perfect - thanks for that answer - it’s what I was looking for.

I’ve been watching your other thread - very impressive what you guys are accomplishing.

Edit:  link to other thread:
https://www.eevblog.com/forum/beginners/static-control-requirements-for-picoamp-measurements-using-ucurrent-gold/

[Wimberleytech]

I have had the uC Gold on my list of things to own.  This thread inspired me to order one 
Last time I looked they were out of stock (a year ago or more), but today they are in stock and on sale. YAY!
US - AUS exchange rate is pretty good, so I feel like I really got a bargain.

Looking forward to its arrival.

[alanapar]

Well, I have wanted to buy a uCurrent Gold, but they seem to have been OOS for some time. I just happened on this thread and so ordered a CurrentRanger, not only in stock, but available in the US 

While I'm interested in using it for its intended purpose, I also have a different application that may be of interest. I am assembling high power DC equipment (Lithium Ion battery systems plus inverter-chargers, etc.) and need to measure micro-ohm resistances (cable, bus, fuses, switches, etc., and bolted joints between components).

Here you run into a problem rather akin to the excessive burden issue with measuring currents: typical general-purpose lab instruments (as distinct from dedicated micro-ohmmeters) have way too small a test current for really low resistance measurements. Plus my Keithley DMM6500 apparently cannot make 4-wire measurements on big transformers or inductors (it goes into endless relay thrashing).

While I can easily use a floating lab power supply to current-source an amp or two of current into the DUT, and use the DMM to measure voltage down to of order 100nV (100 nOhm or less resolution), it's not a very convenient bit of kit for field measurements.

Using the CurrentRanger on the nA range, it is effectively a voltmeter with 10k input impedance, which impedance is negligible compared with my DUT resistance and lead resistance. What I would really like to do is come up with a small, portable (battery powered) 1.000A current source (good for a volt or so lead drop), which can be programmatically switched on/off (or reversed in direction) and integrated with the CurrentRanger SAMD21 processor to cancel thermal EMF's, offset voltage, and LF noise/drift by synchronously differencing successive measurements.

When you are making many such low resistance measurements in rapid succession, you can get a lot of short-term drift in thermoelectric voltages due to varying temperatures of objects, heating of hand-held probes, etc., and as it tends to be a two-handed job applying the probes, it is awkward (to say the least) to be hitting the "rel" button on a DMM and current source power supply on/off button at the same time!

[mendip_discovery]

Could you not just get a low ohm meter? RS do a easy to use auto ranging meter and that just uses a 9V battery. There are also some Cropico DO4 on the bay at the moment and they charge onthe mains but uses a 6V battery to power itself for a while, has a 40mR range up to 4k.

[alanapar]

Could you not just get a low ohm meter? RS do a easy to use auto ranging meter and that just uses a 9V battery. There are also some Cropico DO4 on the bay at the moment and they charge onthe mains but uses a 6V battery to power itself for a while, has a 40mR range up to 4k.

I wasn't familiar with the Cropico DO4, but looked it up and the spec sheet says "10 micro ohm resolution on 40 milli ohm range" (it has a 4000 count display).

For this sort of work, 1 uOhm useable resolution is a minimum, 0.1 uOhm highly desirable. Standards like some Megger/Biddle devices offer the latter in units costing about $5k new.

A good bolted joint in say 1" x 1/2" copper bus (16.5 uOhm/ft) will be a few tenths of a micro ohm added resistance, vs. unjointed bus (equivalent to less than 0.5" or one thickness length of the bus). With poor surface preparation or inadequate bolting force, it can be much higher, so a suitably low resistance test value serves as QA of the job.

Outside of QA'ing joints, 1 uOhm useable resolution is probably sufficient in my case for most purposes. In higher power applications, 0.1uOhm would be better.

BTW, my Keithley DMM6500 offers 1 uOhm 4-wire resolution, which is impressive given it is using only 10mA test current. But it's not useable resolution due to noise and drift, and slow response with the heavy filtering needed to suppress noise to the uOhm level.

Anyway, I thought it would be an interesting project to come up with a $100 or so DIY device.

[Marco]

For this sort of work, 1 uOhm useable resolution is a minimum, 0.1 uOhm highly desirable.

Some of them use a little more than 1A, 200x more.

I'd personally try a PSoC 6 BLE Prototyping Board instead of currentranger.