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Energy Harvesting Design Challenge

28 Posts authored by: vsluiter Top Member
Today while traversing the corridors of the University, I came across this sign:   It's a promotional sign for the nanotechnology lab of the University of Twente, apparently they're diving into the energy harvesting material science. Although probably not relevant to what they're actually doing, the demo is funny; you can light up each LED corresponding to the peltier tile:   No fancy processing needed here: behind each peltier, a small converter modul harvests the energy and pow ...
  Energy Harvesting Solutions: egg timer from Tinkerer on Vimeo.   Hello All! This is my 'grande finale' post in the Energy Harvesting Solutions Roadtest Challenge! It's been a nice challenge, with a lot of technical, well, ehm... challenges!   Thanks! First, I'd like to element14 for organizing this challenge. After that, I'd like to thank Wuerth both for the Energy Harvesting Solutions To Go kit, and for helping me to get a PCB in time, and of course Linear Technology (how do ...
After the last time, I've added the following features / bugfixes to my project   Added button handling; one button to reset egg temperature (if inserting new eggs), the other to switch between showing water temperature and egg yolk temperature The button functionality already existed, but I had tho remap it to other pins, and add some wrapper functions Added buzzer output (controlling the VOUT2 of the LTC3108). When the egg yolk is above (calculated) 85degrees celsius, three beeps are ge ...
  My LCD screen is working! Great, great, great.... I'm so happy this is starting to work well! I don't have much time explaining what I did, but I must give credits to EnergyMicro (again) for their outstanding documentation and code library. Last weekend, while not having any hardware, I dug through AN0057 (EFM32 Segment LCD), and the description of what needs to be done to driver your own display, in combination with the source code is very good.  I didn't fully grasp all concepts ...
Two big anouncements: The roadtest challenge has been extended one week, so the deadline is now friday the 19th. I'm still planning to finish my project this week, otherwise my girlfriend and son will go crazy because I'm spending too much time in my 'lab'. Hooray! This morning, using a flashlight shining close over the floor, I found the LTC2935 back that I lost yesterday evening! Now my project can continue!   Documentation, again.... I finally got my board working, at least harvesting ...
First: the good news:I found the problem! Now the bad news: I've still got to find the solution....   Recap In my post from yesterday I told that the output at Vout on the LTC3108 was very low. It was about 800mV. Today I did some experiments: I desoldered the LTC3108, and replaced it with the one from the demonstration board; to my surprise, the VOUT was zero volt, but the LDO voltage was 2.2V, and the VSTORE (excess energy storage) pin was 5.25V! Was VOUT defective? No, it was badly sold ...
Yesterday I had everything I needed: Components from Farnell, samples of the microcontroller from EnergyMicro, and PCB's from Wuerth / WE-Direkt  ! And to further thank the main contributors to this build: From left to right: coil by Wuerth, LTC3108 from Linear and of course the GiantGecko from EnergyMicro!   Building and debugging - No power, no connection........  I had some trouble getting the design going. I soldered everything in place, omitting a few C's to play with ...
After sending a design to a fab house, I always take a deep breath, and start looking at my design from the relaxed position that I'll just have to wait for my boards to arrive. Now is the time to do some administrative chores such as making a partlist, look at assembly sequence, read through that part of the datasheet that I skipped earlier because I was in a rush... hey.... what's that?   I found some new insights that might be interesting to look at when testing my design: I was lookin ...
The last post was very short, just a picture of the layout of my board, becaus I really, really, really wanted to get into my bed. Which I did. I will now describe what I've done the last few days.   Datasheet reading In my second-last post I pointed out some specifics about the LTC3108. After configuring that, I went on to design the schematic for the EFM32. At first I was feeling a bit awkward about using the EFM32 Giant Gecko series for the simple task I was performing, and especially fo ...
Hell yeah! I finished the schematic and layout of the board. Tomorrow I have very little time, so I'll try to update y'all on friday night what the rest of my plans is..... ...
Hello All,   After my previous post, about having worked to get something finished before 12th of June, where it should have been July, I've started designing my schematic and PCB. Somehow, this process always takes more effort than I see upfront. I had to make parts (footprints and schematic symbols) in Eagle for the LTC3108, Wuerth transformer and the EFM32GG940, and of course determine which parts should surround them. I've considered taking a smaller variant of the EnergyMicro controll ...
vsluiter

I #facepalm to myself

Posted by vsluiter Top Member Jun 17, 2013
    D'oh... I thought the challenge ended on the 12th of June, where it was the 12th of JULY. Which gives me a month of time to continue, where I hade been working quite hard to get a working demo on time. D'oh again.   What now? I'll invest some time in trying to design a PCB to finalize this circuit! As I had described before, I would have loved to do that had I had enough time... I don't think I'll have enough time to get the board made in time due to PCB manufacturing and shi ...
Yes, real eggs were harmed doing this experiment I took last night:   What I forgot to film: Tasting it! Although the part of the yolk wasn't as firm as I hoped it would be, the egg as a whole was very tasty, I must say.   Sequel: This morning I did another experiment, where I didn't let the water get to a full boil; at 95 degrees I turned off the fire, and waited until the yolk would get around 90 degrees Celsius (taking a bit of margin after yesterday evening). The eggs came out f ...
Harvesting: the final frontier... It feels like I've just manouvered my egg-spaceship to a place that had to be explored; after months of travelling through low-power switchmode fields and changing my warp-core throug all low-power modes I finally put it all together; I'm harvesting energy and using that energy to do a complex calculation on the microcontroller.   The pan Here you can see how I prepared my egg pan; on the top I mounted the heatsink and TEG I took from the demo board (mou ...
Calibration - resistance 270 Ohm - 253 = -6% 1k2 Ohm - 1188 = -1% 15kOhm -   15000 =  0% 120kOhm - 114503 = -5%   With 5% resistors, I think this is pretty good; probably the error is distributed between my measurement and the resistor error   Programming the temperature gradient As stated in my previous post, I was modelling the temperature gradient in the egg as a linear model, represented by thermal resistance and thermal capacity. I 'guestimated'  the time c ...