The AVR microcontroller is a leading low power microcontroller that has been around for almost a decade now. Recently, new lower power devices have been added to the AVR family, called the PicoPower AVR microcontrollers.
In this instructable, we show how even the regular AVR devices can be set up and programmed to run off a fruit battery.
Step 1: Preparing the Fruit Battery
Start with a piece of bare PCB. The size of the PCB should be large enough so that you can create 3 or 4 islands on it. Each island will be used to place a half cut lemon on it.
Step 2: Prepare the Zinc Electrode
Step 3: Arrange the Electrodes
Step 4: Add Lemons to the Electrodes
Step 5: Assemble the AVR Tiny MIcrocontroller Circuit
Step 6: Program the AVR Tiny Microcontroller
volatile uint8_t i=0;
Step 7: Battery Performance
The lemon battery performance (ambient room temperature 30 degrees Celsius) was measured as follows:
Number of Cells: 4
Open Circuit Voltage: 3.2V
Short Circuit Current: 1.2mA
Voltage with AVR TIny13V and LED load: 2.5V
Voltage with AVR TIny13V and LED load after 3 hours of continuous operation: 1.9V
Number of Cells: 3
Open Circuit Voltage: 2.3V
Short Circuit Current: 1.0mA
Voltage with AVR TIny13V and LED load: 1.89V
Voltage with AVR TIny13V and LED load after 3 hours of continuous operation: Not measured
Step 8: Achtung!
AVR Microcontrollers are very frugal devices and can operate at voltage down to 1.8V. The current consumption is also very small and the entire circuit including the LED current can be managed with a fruit battery.
Take care to dispose the materials, specially the zinc strips carefully without contaminating your surroundings. Do not reuse the lemons for any purpose after the experiment. Specifically, do not eat the used lemons after the experiment. Although this experiment is harmless and can be performed by children, it is best done under adult supervision. The authors cannot be held responsible for any injury resulting out of such an experiment.