Super Low Electrical Energy Meter || DIY or Buy || Is measuring µA/nA possible the DIY way?
ฝัง
- เผยแพร่เมื่อ 29 พ.ค. 2024
- You can buy the Otii Arc here: www.qoitech.com/buy/
Thanks to QOITECH for sponsoring this video.
Previous video: • How to do Electrical W...
HACKED!: Speaker System gets an IR Remote video: • HACKED!: Speaker Syste...
Make your own Power Meter/Logger video: • Make your own Power Me...
Electronic Basics #27: ADC (Analog to Digital Converter) video: • Electronic Basics #27:...
Facebook: / greatscottlab
Twitter: / greatscottlab
Support me for more videos: www.patreon.com/GreatScott?ty=h
In this episode of DIY or Buy we will be having a closer look at the Otii Arc product. It is a tool that can basically measure µA/nA and therefore calculate the used energy of a low power device. Since such a tool is super handy to have around, I will also try to create my own crude low energy meter in this video. Let's find out whether a Teensy microcontroller and an Op-Amp circuit is capable of measuring µA/nA! Let's get started!
Websites which were shown/used in the video:
hackaday.com/2017/12/22/coin-...
www.pjrc.com/store/teensy32.html
forum.pjrc.com/threads/25532-...
github.com/GadgetReboot/Proce...
www.analog.com/media/en/techn...
www.analog.com/media/en/techn...
ww1.microchip.com/downloads/e...
Music:
2011 Lookalike by Bartlebeats
0:00 Introduction (Why I need to measure µA/nA)
1:45 Presenting the Buy option (Otii Arc)
2:53 Intro
3:12 Testing the Otii Arc
7:01 Coming up with a DIY solution
8:44 Building the DIY circuit
11:12 Conclusion - วิทยาศาสตร์และเทคโนโลยี
Just a quick information because viewers seems to feel like Buy won because the product was sponsored. That was not the case. When I do such sponsored videos I always make sure that I am allowed to say and show whatever I want. I tried lots of different designs for my DIY attempt but all of them were fails. For the video I picked out the most interesting DIY circuit. For me DIY was simply not the winner of this episode. So please stop saying that the outcome was influenced by the sponsor or that I did not try hard enough for the DIY circuit. Lots of stuff goes on behind the scenes of such a video production that does not make it in the final video. Thanks for reading this :-) Stay creative!
I trust you buddy.
We use very sophisticated devices to measure nA, even pA in our labs, and those will cost you an arm and a leg. Sometimes they're cryo-cooled as well.
Brother Just keep up the good work
If negatives are the drops then positives are the Ocean...
I openly accept I was one of the person who commented that thing and now I am literally very guilty about that.
I really respect you 🥺
If you'll make this attempt again, which I read that you might consider it in the future, I'd have a suggestion
Place the first amplifier very close to the measurement point and shield the enclosure, so you get to reject some of those magnetic fields that are around , and lower the bandwidth of the amplifiers to the point where you can still see the desired current spikes using low pass filters. Higher bandwidth = more amplified noise. The first stage is critical, noise from that stage will be amplified by the other stages.
Just to be curious am i the only one who heard a pop at 2.41 and what was it
Was almost expecting to see MarcoReps here in the comment section. Maybe nanovolts wasn't enough to summon him... perhaps if I say picovolts instead? Thermal regulation?
Best comment I have read this year so far 👍
Marco was my first thought as well. A measurement like this would be almost too trivial for him; probably reach a dozen Keithleys, with precision to spare, without getting out of bed. I imagine the diabolical noise floor on the DIY attempt would prompt one of his trademark retching sounds.
You have to say Yoctovolt 3 times in the mirror ..everyone knows that
maybe take a look at EEV Blogs uCurrent schematics, should be possible to make a DIY solution woth this.
I was about to comment the same EEVlog uCurrent/Clone + a Good ADC is the winner!
@@onlyrgu would not say that it would be better than the buy option, but maybe there would be better DIY relults.
I mean it's not that expensive, you can just buy it
@@xani666 You can't, it's out of stock now.
@@koharaisevo3666 Damn, Dave have been slacking!
Make sure to get your op-amps from a reputable source. Op-amps are considered one of the most targeted parts to be cloned due to their higher prices and difficulties to test their features precisely by hobbyists.
I once worked on an internal project where we had a small RF device that need to run for 1 year unattended with just a single CR2032 cell. The device would wake up every day, send an RF pulse with data and go back to sleep. Anyway we did a huge amount of testing with cells of differing makes. In the end the winner by far was Panasonic 2032 cells. From that experience i always use Panasonic button cells these days in all applications.
Good to know. Thanks for the feedback :-)
So close to 1.5k , keep going, great Scott
Your videos are always filled with the most expensive knowledge and instruments too😀😀😀
I built my own remote as well (a few years back) and I OR'd the 4 buttons into another digital pin using diodes. This allowed me to wake the microprocessor on the press of _any_ button rather than just one of them. A neat trick that might be useful to you next time :)
Your idea to come up with a diy solution for µA / nA measurements sounds pretty cool. I think that a low pass filter in the op amp feedback path would have made a significant difference in signal quality.
I've been using a few of these for work and I can vouch that they are extremely reliable and useful tools. Using them in conjunction with their serial function (as well as ability to use external serial devices) makes them excellent for recording events and their power draw on wireless devices. Pricey yes, but their value is incredible.
:-) I like it when a plan dosen't always come together. :-)
It happens......
Great video as always!
Thank for making subtitle. Great video!
You're welcome 😊
I just waited for monday to come!
Thick ropes
As always nice and informative video.
I like your "Stay creative and I'll see you next time!"
Me too :-)
@@greatscottlab Bleib kreativ, und ich sehe dich nnnnnnnaechstes maaal! - doesnt have the same ring to it :)
Pretty interesting project, dude! 😃
Stay safe and creative there! 🖖😊
Thanks, will do!
A video about raspberry pi pico would be great!
Maybe soon ;-)
Well, it basically just runs micropython, like the microcontrollers he showed in the Pyboard video
But I think the Pi Pico has a lot higer clock speeds
it's the new dual-core Arm Cortex M0+ RP2040 running at 133mhz
@@mnbvcx What interest me the most is the use of "Programmable IO"
Yes! Next great video to watch, thank you!
Thanks for watching!
@@greatscottlab You dont need to thank me! Your videos are Great!
I went through so many MOSFETs to find one with the lowest off current. That helped my battery life a lot.
With opamp circuit, you can use a higher resistor value, for example 10k, which creates a 10mV voltage drop, when the current is 1uA. This way, by adding a multiposition switch to change the resistor value, crude low energy meter would work even with very low currents.
But then what happens once the uC switches on the LEDs and it starts drawing tens of milliamps? With your 10k resistor just 0.3mA would drop the voltage at the device to nothing. You'd somehow need to switch to a smaller resistor extremely quickly before the voltage drops.
@@eDoc2020 You're right. For such a case, it's neccesary to modify the circuit, for exaple use a mosfet instead of a resistor, but make it behave like resistor. This way, you can control it's "resistance" very fast. Of course you need some kind of feedback to know, what's the current resistance, and to control it properly.
For the DIY/simplistic quality evaluation I would say the capacitor based method is the easiest way to validate at the nA/uA range (actually in the capacitor method we don't measure current, but in this problem you're not interested in the current but the energy). Prudent selection and identification of the characteristics of the test setup can product relatively useful results. Certainly it tells you about the 10k pullup that should have been 100k !
I used a CR32 battery for my night vision.But that run on 2.7v so i put a resistor between positive from the battery to the night vision tube lasted ages before i changed it.
As always grate vid keep the thoughts flowing till next time.
Now its confirmed you and electronoobs are in very precise competition
The Nordic power profiler kit 2 (PPK2) is much cheaper at around $90 USD, and is also accurate down to the uA range with auto ranging.
You would need a carrier board to operate it though. The Nordic PCA10040 will do the job and is also around $40 USD, so for around $130 USD you get a very similar functionality. The only downside is that you don't get a fancy enclosure...
I have absolutely no affiliation with Nordic, but have used this at work and it did the job very well and with minimal setup effort.
Great Scott I felt that I am missing your projects these days like peltier fridge, Bluetooth speaker, portable monitor and stuff you did in the past
Excellent, very interesting vlog.
Thanks for sharing.
Nordic Power Profiler II. Lots of similar products on the market. But for the cost this seems to have the best specs.
Another super video, thank you...
There is a heck of a lot more to the OTII than measuring low currents (accurately and repeatably)! I bought 1 for home and two for the office where we also have the $35k N6705 from Agilent. I love the OTII, i just works and I know the results will be right unlike any homebrew solution. I've recommended it to a ton of friends and colleagues.
Back in my Electronics Engineering lab, my professor always told me, look at all those antennas, referring to all the component axle leads. When keeping noise to a minimum, traces must be as short as possible with proper shielding. Part of what this commercial meter does would be have internal copper board layers while using ground planes externally. Board design and component selection is critical.
Great video!
Beautiful, now I can measure joule thief's
Placing the opamp directly on the current shunt should help get rid of most of the noise.
Do amplification closest to the source to avoid picking up noise before amplification.
I worked for a year at a company that made remote controls, I still get the shivers looking at a remote, it was a crazy place to work. We did months (or it seemed like it) working on a Sony contract 8am to 12 midnight 7 days a week in a conference room. The AH gave me a $1250 bonus and a line in my performance review "he has potential with this company". Yeah he is stupid enough to work from 8am to 12 midnight. I did get Bluetooth Low Energy out of it and more experience with bare metal embedded systems. Just an FYI, companies making commercial products are on razer thin margins and can be sweatshops. I was surprised about IR communications and the number of custom protocols out there making universal remotes a huge engineering problem. I never would have guess money could be made in this niche market.
Great Video! I was wondering if knowing that you have 2 states (standby and awake), can you use 2 different shunts? One big for low current and one small for high... Cheers!
You are on the right way to develop it , go on.
Hi. For very low current a good option is to go for a logarithmic amplifier. Make sure to choose a op amp with a bias current in the pA range (€€€). Cheers
The nose you measure is the ADC noise from your ARM 12 bit ADC! It has no external reference pin on board.
The ARM Cortex-X Microcontrollers have awful ADC. Only stand-alone ADC able to get rid of processor's noise. Plus a reference voltage for ARM ADC is a 3.3voltage of its power supply. Any decent op-amp with JFET inputs is able to amplify microamps. Wrap it in copper foil, connect to ground reference, give it a precision reference voltage and it will do the job perfectly fine.
Processing ❤️ Nice video
I suppose you can use current mirror and try to charge up a capacitor of known value, measuring time interval with high speed microcontroller. But this current mirror can eat more current than you are trying to measure) Great videos you have here, btw!
@GreatScott! I think you can squeeze out quite a bit more energy from that cell if you use a 'vampire circuit' or Joule Thief. I think that circuit was first coined by 'bigclivedotcom'. It basically boosts the voltage of the cell to the desired voltage and keeps doing that until the cell is completely drained. (The cell voltage will drop over time and at a certain moment, the uC simply wont turn on anymore, even though the cell still has some juice left in it.) Would probably make an interesting video on its own! Cheers en keep up the good work!
1:06 forgot the "h" ;) Keep up the great work :) Your videos always give me great inspiration!
Ohhh damn. No, the "h" is correct. I forgot to add another one behind the "A"
@@greatscottlab this is what i meant. I hope it doesn't bother you too much.
With the Otii Arc not only are you getting good hardware but the software is also worth the steep price. I want one but it is too rich for my simple needs. Instead I got a Battlab One, not too expensive and the software is good. Gives you a good feel about battery life which is all I need. I believe EEVBlog has reviewed both of these instruments for anyone interested.
Yay new awesome video
What would you recommend for a hiking trip after the lockdown Thüringer Wald or Rhön?
You are always very precise in your explanations, and you have created a very nice community for yourself, I hope to succeed one day too.
Best of luck!
@@greatscottlab Thank you :)
Go for It !...good luck.
Pretty easy to measure pico-amp currents with a transimpedance amplifier as used in most photo-diode amplifiers. Much harder to then use the same amplifier to measure mili-amps. A log amplifier chip is a good compromise here. Forgot the part number, but it easily measured from about 10pA to 5mA. That said, an LM662 and a 10Gohm feedback resistor will let you measure 60fA currents :D
Early voltage reference standards used mercury batteries measured by high precision voltage meters as a physical constant, since mercury batteries can have low voltage dip for a given current draw. A minimal current draw to further minimize voltage dips was critical.
It would be interesting to see if the Otii or uCurrent would be suitable to measure that voltage reference itself with low draw, but they'd certainly be helpful in testing volt meter circuits to minimize their current draw for this purpose.
A project I've been toying with for a while is how to derive the metric units based on physical constant measurements in the home lab, and it's a tough chicken and egg problem given that most of the metric units are interrelated, and based on atomic clock definitions of a second; early scientists broke the egg by using artifacts instead for a reason. A mercury cell voltage reference is the easiest candidate as a starting point to break that cycle I've found so far, and then define the remaining units in terms of a mercury cell voltage reference.
Stay creative and i will see you next time. always gets me
I love your handwriting
Thank you! Cheers!
Hi, thanks for making such good contend!
You could have used an Transimpedance amplifier in a coockie-can. I tried this and was able to get gains from 10^6 or more.
Yes Trans-impedance Amp. Ive used a Keithly pico-ammeter and it used a trans-impedance amp as its amplifier.
The pens should charge appearance fees. Hehe. Great instructional content. Greetings from Newfoundland. Dorkily.
There are tricks you can use to make an electrometer (a current meter for values less then a microamp). For a start you need a jfet input op=amp and you need to make it using "dead-bug" wiring techniques. That way you can get down to fA if you cool it down to -40C. I'm in the process of designing one of these for a DIY mass spectrometer right now. The LMC6041 is not perfect but if you want a FSD of 1pA it's easily good enough. The other point is to "spoof" it by using it as a split supply op-amp. IE design the circuit so it uses -3.3V for the ground rail and +3.3V for the positive rail. Also drift and offset can be dealt with not at the input (that would mess with the characteristics) but on the output between this stage and the next. One further point is do not use any kind of cleaner that leaves a residue or touch any of the components as that will leave conduction pathways that will drive you nuts trying to find and sort out.
sounds fun both those are on my list and thanks for the opamp recommendation
Awesome 🔥
Hi, i am currently making a project where i need to measure a current of a small board, i am currently ursing INA219 for this task, but my problemi s that the readings are really unstable if the motor is spinning without any force on the opposite end stopping it, is there any way to fix this either by using different board than INA219 or in code, ty in advance
Idea close to my raison d'etre but perfboard = not good low noise layout choice. Ground plane city, thick copper layout and an avalanche of decoupling cspacitors predicted...
Excellent video!!
2 thoughts: 1) There's a good piece of software, called SerialPlot, which in this case of 'graphing' is a bit easier to use. 2) With the mentioned shunt resistor measuring, you forgot to mention that there's a voltage drop on the resistor, which will result (assuming a fixed supply voltage) a 'voltage drop' on the measured device' supply. So this way, the supply voltage of the device can vary based on the current flow, which can lead to even operation fails (by alternating the actual supply voltage) if the current is high enough.
Hiii, im happy that you finally posted a vid, by the way, what happened to mosfet drivers pt 2?? Pls tell , do we have to wait
Wait for it. It will take a while longer.
@@greatscottlab oke
Hey, what if you would just switch the shunt resistor value to higher one or even place a few of them in series? Voltage drop would be higher, so easier to detect, and since we are talking about analysing a super low-current device, I don't think that it would effect it a lot. You could even turn up input voltage a bit to compensate voltage drop across the shunt.
1:06 You're missing an h behind the A.
1.true
2.good eyes
Make some simple projects using raspberry Pi pico 😊
It is on my to do list
I second this request
@@greatscottlab pog
Very good video
Hehehehehehh time to scale this into a powerful version
And turn on my neighbours tv
100W remote to mess with an entire neighborhood's devices?
@@vgamesx1 That's so 1980's. Atari came out with wireless controllers based on garage door opener (RF) remotes of the time. They worked well enough, but had the inconvenient property of a 2-mile range, so while any given set didn't interfere with each other, anyone in the general vicinity who had another set would interfere. (NOTE: If you have an older-model digital garage door opener system, get it replaced. The codes can be brute-forced in about 6 seconds.)
@@vgamesx1 of course thats the fun
And no one will ever know about it heheheh
Any chance that changing the shunt resistor on an INA21x like the one in your previous energy meter could do something useable ?
I once watched a movie about designing low battery consumption circuits, and the circuit itself was powered by a capacitor while sending the signal, and the capacitors were charged with low current between signal transmissions. This resulted in the battery being discharged with low current.
Try a joulescope for a more accurate and versatile measurement setup or a ucurrent from Dave Jones both great products Dave's is extremely affordable.
Wouldn't that be cool to have a diy or buy episode about a home thermostat. I would really like to know if I'd be better buying a new one or build one myself!
Using the Otii Arc in that second mode reminds me of a Source-Measure Unit (SMU), which would explain the high price point, those usually cost *thousands* of dollars.
indeed it describes itself as a 2 quadrant smu if i remember correctly
Could you make a video about DIY linear motors? Do you think it'll be a good option for 3d printers? You're my electronics teacher in YT :D
Amazing
let's get started
Great topic! I've been wanting to try to make a cheap DIY current meter myself, even cheaper than the current ranger. One of the STM32L discovery boards (~$12) has an extra processor to measure sleep current down to nA. Instead of expensive precision resistors as in the current ranger, I was thinking of normal resistors and software calibration. I was thinking of using an op amp module. The current ranger uses cmos switches to select the range, but loses some readings as the software auto ranges. Since the op amp modules are cheap, another option is to connect the shunt resistors I'm series, then short out the resistor with a diode or mosfet when it goes into overrange. Using an internal power supply can give you more voltage drop range in the measuring circuit so you don't need to deal with such small voltages. Maybe auto ranging is the hardest problem.
I'd say, give it another go on DIY current measurement. If you hit a problem, go back to the drawing board. It will certainly be educational.
The TI MSP432 launchpad also has facilities for measuring low current. These devboards are probably the best low-cost way to measure low currents drawn by projects.
@@eDoc2020 I haven't used the TI devboard, but the ST current measurement is integrated on the PCB so is convenient to measure processor power, but can't measure external power as far as I know.
@@ch94086 The TI board was set up so you could split it into separate interface and microcontroller halves. If you undo the jumper carrying power to the microcontroller half you can connect an external load to the 3.3v output instead. The problem is I couldn't figure out how to start measurement without an active JTAG connection, although it's definitely possible with the hardware. I might have had a bit of luck by starting measurement with the halves connected and then undoing the jumper, but I don't really remember. Unfortunately my board is no longer functional so I can't go back and check.
DIY of course !
Otii Arc! Expensive but soooo good
Fantastic seekers
5:20 looks like the infrared signal is visible through the power consumption. Nice example of a side channel attack.
I've actually used this to measure the signal sent by remotes (both IR and RF) without needing to have a dedicated receiver.
How would you design a solution that would scale to measure voltage and current of hundreds of battery cells in a large battery?
Would you use CAN bus to reduce the cabling?
I used current - voltage converter circuit to measure reverse pn junction current in liquid nitrogen temperatures in ranges of 100s of femtoamps 35 years ago. There was an electrometric hybrid opamp with resistive network in feedback circuit and the result was pretty satisfactory even concerning noise. I would do something similar to measure such a low current consumption nowadays.
Thanks for the feedback :-)
@@greatscottlab to make it more clear - i would suggest to use opamp to sink current flow to virtual ground which allows to use much greater resistance to determine the desired voltage drop thus overcoming the need to amplify uV voltages
Bro i love u r videos .pls make a arduino uno based capacitance testor or an lcr meter
How about increasing the value of the shunt resistor? In this case, we can have higher voltage value for ADC to process?
I want to know if you can read milli Amps with a DIY version using Arduino, or it is too slow?
You should try the INA212 for the amplification it is designed for measuring low currents
You should have used a zero offset unity gain buffer along with a pga adc. Analog discrete stages would not do well expectedly
60th comment is mine ❤️
Great video
Greatt Scott ❤️
Awesome! Thank you!
Hi, for microcontroller I use MSP430 series by Texas Instruments (MSP-EXP430FR6989), and for current shunt sensor INA186. A greeting
I guess this may be the longest intro+pre intro video in this channel )
Possible......
Thanks for this vedio.
i want to build a short circuit tester do you have any idea.
Hello i love your videos 😍
Glad you like them!
Hmm! I'd love to see you revisit this with PCBs from our favorite supplier, possibly using some of the ED tricks the commercial product did (massive holes or slots for isolation etc). There has to be a way to make the output less noisy without breaking the bank? Of course the PCB is gonna take some time to design and route but it's not that big of an investment? Our favorite PCB supplier drove the cost "down down down" :-)
I love it
You should try out a High Gain Instrumentational Amplifier from Analog Devices. Combine that with a proper ADC and you should be good to go for a diy Version :D
You need a self correcting feedback loop circuit. Some circuit like the circuit which is used to calibrate crystals for timers.
Have you heard about the Power Profiler Kit II? It does basically the same but for less money.
2:15 NICE.. I mean, yea price is high but number is NICE
pretty close to the µ-current, but fair, dave is a really good designer
I would do a logic controlled variable shunt with comparators that way you don't have to read microvolts
Nice work thank you 👍
I hope you make a video to how build 4to 20 ma generator for analog control by using Arduino
how about an amp04 or something similar? saves the trouble of building an instrumentation amp with op amps.
Would it be possible to discharge a small capacitor on your remote control circuit for a day or two and follow its voltage, and calculate the draw that way?
Yes, but keep in mind multimeters draw a small amount of current when measuring voltages so that could skew the results if you're not careful. Most digital multimeters have a 1-10 megaohm resistance across the probes. At very low measurement values this tiny draw can become significant. Also note some capacitors may have slight leakage.