I made progress on my first robot project (see http://www.societyofrobots.com/robotforum/index.php?topic=6188.0
I now have a question about power source. I use a Tamiya low voltage motors + gear box. The rating is 3 to 4.5V. The MCU is an Arduino board. My current setup is a pack of 6 AA batteries to
power the Arduino and the motors. To reduce the voltage for the motors I used a LM7805 linear voltage regulator. I know this is not ideal (waste of energy), but I can't find an ideal solution.
Here are my options (as far as I know, there are probably many more):
1. Use a switching regulator instead of a LM7805.
2. Use 3 AA batteries ( not regulated ) for the motors and another battery pack for the arduino (I have a 9V battery pack I could use)
3. Use 6 batteries, remove the voltage regulator and adjust the voltage by PWM (through the SN74410 IC)
Option 1. is feasible but I'll have to order the chip.
Option 2. is maybe the best solution, but the 9V battery has a low charge (150/200 mAh)
Option 3. is the easiest, but I afraid it will reduce the range of values usable for the PWM.
Any idea, suggestions?