That's why, I came up with the AA Undershield. It uses 2 AA batteries and boosts the voltage up to 5V, using a MAX756 IC to power the Arduino.
You may ask why I'm not simply using 3 or 4 AA batteries to power the Arduino. The reason why, I'm not using batteries to drive my Arduino directly, is that they're not regulated. Right after, you've recharged your battery, it may supply 1.4V, even though it's rated for 1.2V, so there's a risk of supplying your Arduino with too high or too low voltage.
Here is a video of the Arduino Diecimila and the AdafruitWaveshield attached to the AA Undershield. I've uploaded an example code, that changes the playback speed, when you turn a potentiometer. Other analog sensors will also work.
I apologize for the poor sound quality in this video. The mic in my camera is really bad.
The AA Undershield can also be used with many other 5V devices.
Step 1: Get the Parts
- A prototyping PCB that has the same size as your Arduino board.
- A battery holder.
- A MAX756 Integrated Circuit. There is a lot of boost converters out there, but I used the MAX756, cause I had a couple of them lying around.
- A 8 pin IC socket
- A 22uH coil.
- A 1N5817 or 1N5818 schottky diode.
- A 220uF Electrolytic capacitor.
- A 100uF Electrolytic capacitor.
- A 100nF Ceramic capacitor.
- A 100kohm resistor.
- A 110kohm resistor (I didn't have one, so I connected a 10k and a 100k in series).
- Two spacers to make space between your Arduino board and your shield.
- Two screws for the spacers.
- Two nuts for the spacers.
- Four spacers to make space between the undershield and the surface, you're placing it on (These are only needed if you choose to mount your battery holder underneath the shield).
- Four screws for the spacers (These are only needed if you choose to mount your battery holder underneath the shield).
- An Arduino or Freeduino board. I used a Diecimila, but it should work with the other boards just as well.
- Two AA batteries.
- An on/off switch (optional).
Step 2: Drill the Holes in the PCB
If you choose to mount the battery holder underneath the shield, you should drill 4 holes in each corner of your PCB for the spacers.
Step 3: Start Soldering
When you're done soldering, check your your circuit for mistakes. If you didn't find any mistakes, then hook up your circuit up to the batteries and a voltmeter. You should get around 5V and it should not be higher than 5.30 volts or lower than 4.90 volts.
Step 4: Mount the Battery Holder
Step 5: Mount All the Spacers and Your Arduino Board
Then mount the two spacers for the Arduino board.
After you've done that, it's time for mounting the Arduino board on top of the shield using two screws.
Then insert the positive wire (in my case the red one) into the place in the power header that is marked "5V". Insert the negative wire (in my case the black one) into the place in the power header that is marked "Gnd".