Joule Thief Energy Harvesting Experiment w/Low Voltage Solar Cell
Stored energy 1/2*C*V^2 = 0.48 Joules
3-Axis Accelerometer Now Available
The initial test code for the MMA7660 breakout board is now complete. The $5.75 boards are now available in the product section http://www.madscientisthut.com/Shopping/agora.cgi?product=CNC%20/%20Robotic%20Sensors The assembled and tested MMA7660FC breakout board is on sale now for $5.75 was $9.99, and an unassembled PCB is available for $0.99
To download code samples, visit the forums at http://www.madscientisthut.com/forum_php/viewtopic.php?f=13&t=5<>br>
Code samples are currently available for PIC HiTech C and Visual Basic.
The 3-axis G sensor breakout board is based on the Freescale MMA7660FC. The MMA7660FC is an I2C Digital Output , very low power, low profile capacitive micro machined accelerometer featuring a low pass filter, compensation for 0g offset and gain errors, and conversion to 6- bit digital values at a user configurable output data rate. The device can be used for sensor data changes, product orientation, and gesture detection through an interrupt pin (INT). The device is housed in an extremely small 3mm x 3mm x 0.9mm DFN package.
IC Features:
* Low Power Current Consumption
o Off Mode: 0.4 µA
o Standby Mode: 2 µA
o Active Mode: Configurable down to 47 µA
* Low Voltage Operation: 2.4 V – 3.6 V
* 3-Axis ±1.5 g MEMS Sensor and CMOS Interface Controller Built Into One Package
* Configurable Output Data Rate From 1 To 120 Samples A Second
* Auto Wake/Sleep Feature for Low Power Consumption
* Tilt Orientation Detection for Portrait/Landscape Capability
* Gesture Detection Including Shake Detection and Pulse Detection
* Robust Design, High Shocks Survivability (10,000 g)
Breakout Board Features:
* 0.1″ spaced pins in a 2 row by 4 pin configuration , rows are spaced 0.6″
* Independent power for DVDD and AVDD with 0.1uF bypass capacitors mounted directly below the IC.
* 0805 resistor pads for SDA and SCL pull-up to DVDD, allows flexibility for I2C bus pull-up location. You can use internal pull-ups from your micro-controller, or pull-ups from another location on the I2C bus, or populate the breakout board resistors (two 4.7k Ohm 0805 resistor included with each board)
Update on Homemade Zinc Copper Battery Experiment
Here is an update on the Joule Thief Kit experiment, where I was trying to charge a NiMh battery using a homemade single cell Copper Zinc battery. See this post from October https://madscientisthut.com/wordpress/?p=46
The first experiment using a zinc plated bolt failed as the zinc plating came off of the bolt in about one day. So I set off to make a much better zinc plate. I found a certain unnamed Copper coin made after a certain date was greater than 97 percent Zinc. Zinc has very low melting point of 787.15 degrees Fahrenheit. I have a wood burning stove that makes for a nice melting furnace. I took about 50 coins and stuck them into a tin soup can and inserted them into the fire and after about 10 minutes I had a nice molten Zinc soup. ( I do not recommend doing this because it is dangerous )
I carefully removed the soup from the fire and poured it slowly (to prevent the copper chunks from coming out of the bottom of the can) onto a large #10 sauce can that was inverted. I let it cool for a long while before removing the zinc slug from the can.
I put this battery together using a plastic peanut butter jar, a 3/4inch x 8 inch Copper pipe and the zinc slug. added some water, salt, and vinegar. I connected the Joule Thief Kit with clip leads to the Copper and Zinc. Took the output from the Joule Thief Kit and rectified it with a 1N4001 diode and put that into a completely depleted NiMh battery ( I use a white LED in series to indicate if the circuit is operating). This is the same schematic circuit from the late October post. This battery charger has been running since November 1st and the NiMh battery Voltage is up to 1.237V. Since I am not exceeding the 1/40th current rating this battery will not overcharge.
The only maintenance I have been doing is adding a little vinegar every time the liquid level drops from evaporation (that is about 1/16th cup a week), I will post another update when I find time.
I suspect that I can charge 4 NiMh batteries in series with this circuit, and that might be a future experiment.
I know many of you think how can this be useful since it takes a month to charge the NiMh battery, but there are many situations where I think this could come in handy. This low cost circuit provides a source of light as well as being a battery charger. There are plenty of places in the world where electric power is not a luxury of life, and there are plenty of things that you can make low voltage sources with that the Joule Thief circuit will happily run off of. This is what energy harvesting is all about, lets make some use out of something that we could not use before.
Update on Homemade Zinc Copper Battery Experiment
Here is an update on the Joule Thief Kit experiment, where I was trying to charge a NiMh battery using a homemade single cell Copper Zinc battery. See this post from October https://madscientisthut.com/wordpress/?p=46
The first experiment using a zinc plated bolt failed as the zinc plating came off of the bolt in about one day. So I set off to make a much better zinc plate. I found a certain unnamed Copper coin made after a certain date was greater than 97 percent Zinc. Zinc has very low melting point of 787.15 degrees Fahrenheit. I have a wood burning stove that makes for a nice melting furnace. I took about 50 coins and stuck them into a tin soup can and inserted them into the fire and after about 10 minutes I had a nice molten Zinc soup. ( I do not recommend doing this because it is dangerous )
I carefully removed the soup from the fire and poured it slowly (to prevent the copper chunks from coming out of the bottom of the can) onto a large #10 sauce can that was inverted. I let it cool for a long while before removing the zinc slug from the can.
I put this battery together using a plastic peanut butter jar, a 3/4inch x 8 inch Copper pipe and the zinc slug. added some water, salt, and vinegar. I connected the Joule Thief Kit with clip leads to the Copper and Zinc. Took the output from the Joule Thief Kit and rectified it with a 1N4001 diode and put that into a completely depleted NiMh battery ( I use a white LED in series to indicate if the circuit is operating). This is the same schematic circuit from the late October post. This battery charger has been running since November 1st and the NiMh battery Voltage is up to 1.237V. Since I am not exceeding the 1/40th current rating this battery will not overcharge.
The only maintenance I have been doing is adding a little vinegar every time the liquid level drops from evaporation (that is about 1/16th cup a week), I will post another update when I find time.
I suspect that I can charge 4 NiMh batteries in series with this circuit, and that might be a future experiment.
I know many of you think how can this be useful since it takes a month to charge the NiMh battery, but there are many situations where I think this could come in handy. This low cost circuit provides a source of light as well as being a battery charger. There are plenty of places in the world where electric power is not a luxury of life, and there are plenty of things that you can make low voltage sources with that the Joule Thief circuit will happily run off of. This is what energy harvesting is all about, lets make some use out of something that we could not use before.