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Energy Harvesting Design Challenge

17 Posts authored by: gelmi
I would like to sum up all the work I have done in one post for those who did not follow this RoadTest and do not want to go through all the posts one by one.   Project descriptionThe other night I was making diner in the kitchen and I saw a blinking red LED on my carbon monoxide detector, indicating that I need to replace batteries. That is when I realized that some energy harvesting technique should do the trick for me next time with a help of some hack. These types of alarms are usually ...
Like Victor, I have finished my movie showing off the project. At the end of the week I will try to sum up what I did and learned during this RoadTest. But right now with no further ado, I present to you the carbon monoxide detector project supplied by energy harvesting.   ...
I have soldered and tested my board and I must say – it works great! Here are some pictures of the whole thing: detector, harvester and STK with uC.   I have done some energy tests. The output of the harvester chip has 0.1 F supercap. I used LTC3108-1, so the output is 3 V. As I have mentioned in one of my previous posts, I use internal EFM32 5V reference, so the usable voltage for me is 2.5-3 V. Below, there is a graph of discharge process. It takes more than 2 h to drain the 0. ...
gelmi

Homemade PCB

Posted by gelmi Jul 9, 2013
I see that everyone is finishing projects before deadline I wanted to order a custom PCB for my project, but it takes about 7-14 days, so I decided to go back in time, when I lived in my dorm. Me and my friends were creating our own PCBs back then. The process is really simple. Create schematic and PCB design. Print the layers (laser printer) and iron them onto the raw copper board. Soften the paper with water mixed with citric acid and washing-up liquid. Peel off the paper when it ...
While my project is not quite finished yet, I would like to share my thoughts about the EH seminar I attended on Tuesday two weeks ago. There were people from all over Poland, even from the opposite site of the country. That shows that companies here seriously take energy harvesting techniques under consideration in their current and future designs. Since EH is quite new, there is still much to learn for all the engineers, despite their experience in electronics. The seminar was led by element14 ...
gelmi

Energy optimized code (II)

Posted by gelmi Jun 29, 2013
In this post I would like to describe what the code does when the chip is woken up once a minute or when the TEST button is pressed. I will mention only the most important parts of the code. If you would like to investigate it more, you can check source files which are uploaded with this post. The picture below presents the basic dataflow of the code. After the wake up the reset cause is being checked. If the reset was not caused by any of the implemented EM4 wake up methods, in other words  ...
gelmi

Energy optimized code (I)

Posted by gelmi Jun 27, 2013
I finished writing and testing the code for my project. I do not know if you remember, but in one of my previous posts I measured the average current consumption of a simple, cheap CO detector to be around 500 uA (@3,3 V) – that is being consumed by the whole standby and sensing functionality. This is a way over what I can supply from the TEG when harvesting energy from hot water tap. That is why I used Energy Micro STK with EFM32 Giant Gecko on board to create my own CO detector device. B ...
As promised I uploaded the video from the tests. Because I do not have a special equipment to test the sensor with the exact ppm value gas concentration, I wondered how to create CO gas in home conditions without risking CO poisoning. I came with this idea. When something organic burns it creates CO2 and H2O (complete combustion), but if there is not enough O2 in the environment (half combustion) the CO instead of CO2 is produced. The simple way to do that is to burn something in a closed jar. T ...
gelmi

CO sensor

Posted by gelmi Jun 15, 2013
To sense carbon monoxide concentration, I took many sensors into consideration. The one I have chosen for my design is TGS 5042 from Figaro. There are 3 main reasons that this sensor is perfect for my application: This is an electrochemical sensor – it does not need power supply. It is filled with some chemicals which in reaction with carbon monoxide produce current and the sensor works as current source. Plus, other gases and temperature (especially home environment temperature range) h ...
gelmi

Energy sweet spot

Posted by gelmi Jun 3, 2013
I am still developing my project. It is not ready yet, but I would like to share with you two things. The first one is the plot of TEG voltage just after I turn off the hot water tap. This data is when the TEG is under load (STK temperature demo). The board is still operational for over 15 minutes. This is how the device can still harvest and store energy after the water stops to run. The other thing was a little bit unexpected for me. I have noticed this after some time. When hot water runs th ...
gelmi

Hot water harvesting

Posted by gelmi May 17, 2013
I have finally created a prototype of energy harvester for my project. Let's start from the beginning. I managed to get a solid copper brick with a hole drilled through. Unfortunately, the diameter of this hole was too large to tightly fit the battery pipe, inside which hot water runs. The difference between diameters was approximately 4 mm. An idea came to mind to use thermopad. It is the flexible and squeezable small piece of mat which conducts the heat pretty well. So, I used it to feel the v ...
Today I did some successful trials with energy harvesting from a hot water  tap. This post is just a teaser, because it is almost midnight and I have to get up early. The photo below presents a bathroom battery with a TEG attached to and a multimeter (mV). The Peltier module is without load in the picture. When it is connected to LTC harvester chip and hot water runs from the tap, the voltage is about 55 mV. As Victor stated and I also agree, energy harvesting is very tricky. You have to u ...
I have started my energy harvesting trials to power up the carbon monoxide detector from the difference between ambient and wall temperature. Firstly, I checked these differences in some long periods of time in couple of rooms at home. I tested both the internal and home outline walls. And I must tell you, I was surprised. Despite of what I have read in the building construction companies fliers, my walls were always a little bit warmer than the air around them. Here is one data plot from the me ...
PrologI have measured the power consumption of this detector, that I got recently. Many of you have already checked the energyAware Profiler application from Simplicity Studio and know how to use it, but it is also possible to monitor the power consumption of any of your external applications with the STK, even if your external device does not run EFM32 chip. OK, so maybe not all external applications but the ones that can be power supplied from VMCU domain on STK. Also remember that the maximum ...
Hi, Yesterday I got the carbon monoxide detector that I had ordered a while ago for roadtesting and I wanted to share the video from the teardown. I did this teardown in order to disable the piezoelectric buzzer, which is very loud, especially when you want to test it while you are in the short range. The device itself is a simple design. The one thing I am not sure what it is inside, is the metal can. The user manual says that the detector is only for carbon monoxide, but this metal piece can b ...