By using energy harvesting technology I devised a method to power the Internet Of Things board: Mediatek Link it One. By creating a simple circuit using energy harvesting ICs such as the LTC3108 I was able to harvest enough energy from solar sources in low-light conditions to power the Link it One. This board can also be used to power Arduino boards and PICAXE micro-controllers.
In this instructable I shall explain how I did it.
• SSOP to DIP layout breakout board such as these, the side with 0.65mm spacing shall be used http://ebay.eu/1NLeJsQ
• LTC3108 Energy harvesting IC from Linear electronics in the SSOP 16 Lead package (I got these as a free sample
• Coilcraft 1:100 transformer (I also got these as a free sample)
• 330pF capacitor (0805 SMD or through-hole)
• 1nF capacitor (0805 SMD or through-hole)
• 1uF capacitor (0805 SMD or through-hole)
• 220uF Capacitor (either SMD or through-hole)
• 470uF capacitor (either SMD or through-hole)
• Some headers 2.54mm spacing
A N-Channel MOSFET
A 1M resistor
• A type of prototyping board e.g.
• Some wire for connections on the prototyping board
• A solar cell (should produce 0.55v in bright sunlight.
The LTC3108 coupled with the appropriate circuitry is able to step-up voltages as little as 20mv to 3.3v. I made the suggested circuit as shown on page 1 of the datasheet which I have included for your own convenience.
This energy harvesting IC unfortunately only comes in very small surface
Carefully align the IC on the breakout board (in the correct orientation, the side with
Solder in a header on each side of the
Then solder the transformer in place.
There are two ways of doing this, either try soldering the transformer directly onto the proto-board or mount the transformer on small stilts. I tried both and found the stilts method to be the best.
Test that the transformer is correctly connected. The 1 coil will have a resistance of 0 ohms. The 100 side coil will have a resistance of about 340 ohms. If
Then solder in the 330pF and 1nF capacitors next to the transformer.
Notice how the small SMD caps are connected near the transformer.
The large SMD capacitor is 470uF and is used to smooth Vout and provide high current bursts when needed.
Connect VS2 to ground
Connect VS1 to VAUX.
Connect VS1 and VAUX to ground via the 1uF capacitor
I soldered in a 0.33F super cap between VStore and GND. At this point I chose to configure the LTC3108 to output 4.1v rather than the 3.3v that I tested the circuit
I used a ZVN2106A N-channel MOSFET
An 10 K SMD resistor was used to pull the gate down to ground.
I used a logic level N-channel MOSFET. Source connects to GND. Gate connects to Pgood pin with a 1M pulldown resistor. Link it one GND connects to drain while Link it One Bat+ connects to Vout
I used a solar cell to check that the board worked.
After some testing I found that the energy harvesting circuit was able to power the LinkIt One board for about 10 minutes using the