The Infrared Remote: A DIY Power Analysis Experiment

In this episode of DIY or Buy, I decided to test out the Otii Arc Power Analyzer and measure the energy consumption of my infrared remote. The Otii Arc is a commercial power analyzer that can accurately measure very low levels of current, making it an ideal tool for analyzing the energy efficiency of devices like my infrared remote.

I started by plugging in the Otii Arc and connecting it to my infrared remote using its positive and negative terminal connectors. I then set up the device to output 3V and activated it, allowing me to start a new recording. To get accurate results, I removed most of the wires from the remote and connected only the necessary ones to the Otii Arc.

The first test revealed that the average current levels were around 1µA, which is an extremely low value. However, this was not the end of the story. When I asked the developers of the Otii Arc about the negative readings I had seen in my results, they explained that these values were simply a result of the device's internal calibration and did not affect the accuracy of the readings.

Despite some technical challenges, I was able to achieve accurate measurements using the Otii Arc. To do this, I had to modify the device's configuration to output higher voltage levels, which allowed me to detect the small current changes caused by the remote's infrared signal.

The commercial version of the Otii Arc is a high-end power analyzer that can accurately measure very low levels of current. However, it also comes with a hefty price tag and requires careful calibration and setup. In contrast, my DIY version of the device uses a lower-cost microcontroller and operational amplifier to achieve similar results.

In this article, we will explore the technical details behind measuring energy consumption using the Otii Arc Power Analyzer. We will examine the design challenges associated with analyzing very low levels of current and discuss some of the solutions that can be used to overcome these challenges.

One of the main challenges in measuring very low levels of current is the requirement for extremely sensitive instrumentation. The Otii Arc, for example, uses a 6-ohm resistor to amplify the small voltage changes caused by the infrared signal from my remote. However, this requires an extremely sensitive analog-to-digital converter (ADC) to accurately measure these changes.

The ADC used in the commercial version of the Otii Arc is a 24-bit device that can accurately measure very low levels of current. However, even with this high level of sensitivity, there are still some limitations to consider. For example, if the infrared signal from my remote were too weak, it would be difficult for the ADC to detect.

To overcome these challenges, I decided to use a lower-cost microcontroller and operational amplifier in my DIY version of the device. The microcontroller used is a 32-bit ARM one with a clock speed of 84MHz, which provides sufficient processing power to handle the data from the ADC. The operational amplifier used is an OP177 ultra-precision Op Amp, which has a low offset voltage and high gain, making it ideal for amplifying small voltage changes.

The design of the DIY version of the Otii Arc required careful consideration of several technical factors. First, I needed to choose a suitable microcontroller that could handle the data from the ADC. After some research, I decided on a Teensy 3.2, which provides sufficient processing power and has a 16-bit ADC.

Next, I needed to select an operational amplifier that could amplify the small voltage changes caused by the infrared signal. After some searching, I found an OP177 Op Amp that met my requirements, including low offset voltage and high gain. I then built up a differential Op Amp setup on a piece of perfboard with a gain of 100.

To connect the amplifier circuit to the microcontroller, I used an analog input to read the amplified voltage levels from the remote. I then wrote some code in C++ that spits out the amplified voltage levels in a number format, allowing me to visualize the current changes caused by the infrared signal.

The final result was quite impressive - my DIY version of the Otii Arc Power Analyzer was able to accurately measure the energy consumption of my infrared remote using only a few simple components and some basic electronics knowledge. Of course, this is not to say that my DIY device can match the commercial version in terms of accuracy or sensitivity, but it demonstrates that with careful design and attention to detail, even simple devices can be used to make accurate measurements.

In conclusion, measuring energy consumption using power analyzers like the Otii Arc requires a combination of technical knowledge and careful setup. While the commercial version is certainly more accurate and sensitive than my DIY device, my results demonstrate that even simple electronics can be used to make accurate measurements with the right design and components.

As always, I would like to thank you for watching this episode of DIY or Buy. If you have any questions or comments about the technical details behind measuring energy consumption using power analyzers, please feel free to share them in the comment section below.

WEBVTTKind: captionsLanguage: enSome of you might remember this infrared remotethat I built in a previous video for my Speakersystem.Now don't worry, it still works perfectlyfine.By pushing the upper button, the microcontrollerwakes up from its sleep mode and as soon asI push the other buttons, the infrared LEDsends out the programmed data.But there is just one slight problem; andthat is that this is already the third coincell the remote is draining in just 4 years,even though I calculated that one of themalone should have been able to power the remotefor over 100 years in sleep mode.Of course I didn't expect such a long runtime since I use the remote from time to time.But I at least expected a run time of around5 to 10 years which means it was time to conductmore scientific measurements.My used coin cell comes with a capacity of0.21Ah and a nominal voltage of 3V which equalsa theoretical energy of 0.63Wh.Now to calculate the energy consumption ofthe remote we would have to track the appliedvoltage as well as the current that is flowing,then multiply those two values and sum upthe area underneath this power line.I know it sounds kind of complicated; butthankfully I already built such an energymeter during a previous video of mine.But after hooking the remote up to it; itwas not really hard to figure out that thisDIY meter is not suited for measuring currentsin the µA region.Luckily the company Qoitech reached out tome and sent me their Otii Arc Power Analyzer,Log Sync & Power Supply product.Now I will test this product extensively ina couple of minutes but for now let me tellyou that it measured the super low currentconsumption of my remote without any problemsand also calculated the used energy flawlessly.But what stood out to me at the start whileusing this product was its rather high pricepoint of $699 which is not not really affordablefor the average tinkerer.That got me thinking how difficult it actuallywould be to measure super low current flowsand that is why in this episode of DIY orBuy I will firstly properly test out the OtiiArc and see how it works and afterwards Iwill try to create my own crude DIY superlow energy meter in order to find out whetherwe should use a DIY solution for such a problemor stick to the commercial product instead.Let's get started!This video is sponsored by Qoitech who producethe Otii Arc.First off let's have a closer look at theproduct.I have to say its metal design is elegant,minimalistic and simple; just how I like it.The accessory the product came with was alsosimple because it was just one Micro USB cable.That means all I had to do was to plug oneend of the cable into the Otii Arc and theother one into my computer.Then I downloaded and installed the software;and just like that I was ready to create anew project which promptly asked me to adjustthe settings for the measurement.And because I didn't fully understand whatall of those values meant, I quickly browsedthrough the manual which pretty much answeredall of my questions.Now initially I thought, I would have to adda current shunt in series to the battery inorder to measure the current.You know because a current shunt is more orless a resistor with a known value and assoon as current flows through it, it obviouslycreates a voltage drop that a system can measure.And since we know the precise voltage andresistance value, we can then calculate thecurrent.And measuring the voltage of the remote iseven simpler by just connecting to its positivevoltage terminal.Now the Otii Arc does support this measuringmethod by connecting to the pins which arebrought out to the front of the device.And of course I tested that with a resistorvalue of 6ohm which I basically soldered inseries to the remote.After then adding this value in the setupalong with the option to track the ADC voltage,I simply clicked start and began a new recording.After letting the system record for threeminutes while occasionally waking up the microcontrollerand sending out infrared signals, I stoppedthe recording and had a look at the graph.It seems like the super low current consumptionwas accurately tracked and even the highercurrent demands were no problem.And by selecting a time interval of for exampleone minute, the software automatically spitsout the used energy which we can now use tocalculate a more realistic lifetime for onecoil cell of my remote which is close to whatI initially expected.A possible reason why all my coin cells diedearlier however is the available battery capacityat different current draws, but make sureto have a look at the link in the video descriptionto learn more about that.But anyway; while I think that those measurementswere already pretty good, we can actuallyget a higher precision.For that I removed pretty much all the wiresand even the battery of the remote and simplyconnected its positive and negative terminalto the Otii Arc lab bench connectors.After then editing the project settings tooutput 3V, we can click OK, activate the outputvoltage and start a new recording which Ialso ran for 3 minutes.This time though you can see that we got currentlevels down in the nA region.You might also be wondering why there arenegative values for which I actually got ananswer from the developers itself so feelfree to pause and read it.But in a nutshell the average readings willalways be correct and we should never forgetto calibrate the Otii Arc.Now with all of that being said I think wecan all agree that this is one fine tool butwe of course want to go the cheaper DIY route;so let's open up the housing of the deviceand have a closer look at its inside.There is actually quite a lot going on thisPCB; but all we care about for our DIY versionis the method of measuring the voltage acrossa current shunt which is why I followed thetraces of the pins responsible for that anddid a bit of google searching along the waywhat all components are supposed to be.The heart of the system is of course a fastmicrocontroller, in this case a 32-bit ARMone with a clock speed of 84MHz.This microcontroller is connected to an Analogto Digital Converter or ADC which comes witha high resolution of 24-bit.The problem is though that if for example1µA is flowing, the 6 ohm resistor will onlycreate a voltage drop of 6µV which is sucha low voltage value that even the used ADC,which practically only uses 16-bit, will haveproblems differentiating such low values.By the way, feel free to watch my video aboutADCs if my previous sentence did not makemuch sense to you.But anyway to solve this problem the circuitalso comes with lots of operational amplifierswhich in a nutshell amplify the current shuntvoltage for the ADC.So in theory this setup does not seem toohard to replicate in DIY style, right?Well, I started my DIY journey by lookingfor a microcontroller and ultimately decidedon this Teensy 3.2 which not only has a fastclock speed but also a 16-bit ADC.And while finding a suitable microcontrollerwas relatively easy, finding a suitable OpAmp was certainly not because we need onewith a low offset voltage and very low noise.Eventually though, I found this OP177 onewhich is an ultra precision Op Amp.With it I built up a differential Op Amp setupon a piece of perfboard with a gain of 100which I connected to my remote and my oscilloscope.But as you can see while trying to amplifyµV values, the output is more or less prettymuch only noise which converted into µA wouldequal a way too high value.The problem is that a simple DIY solutionlike this will not be able to successfullyand accurately amplify such low voltage values,you will need a way more complicated Op Ampdesign with more stages and calibration pointsto get any useful results.Also you will have to take care of noise problems;which the commercial PCB did take care ofthrough different design choices and componentselections.So all in all measuring µA or even nA inDIY style is only possible if you invest lotsof time and money and that is certainly notwhat we want from a DIY design.But our DIY Op Amp circuit is still definitelygood enough to accurately amplify mV whichmeans it can be easily used to measure andcalculate the higher current consumptionsof my remote.So let's connect the amplifier circuit toan analog Input of the Teensy and write abit of code that basically spits out the amplifiedvoltage in a number format.To better visualize those numbers we can alsouse a bit of code in the processing softwareto create this crude current tracker whichas you can see creates a current waveformwhich is very similar to what we have seenearlier with the commercial product.So all in I have to say that I failed measuringsuper low currents the DIY style but DIY isstill good enough for measuring mA valueswhich is something.But since this episode was about super lowenergy meters, I have to declare that theBuy option is this time the winner.But what do you think; let me know in thecomment section below.As always thanks for watching.Don't forget to like, share, subscribe andhit the notification bell.Stay creative and I will see you next time.