here's the pitch:
following tom igoe's arduino on a breadboard i now have an atmega168 chip (programmed through arduino) that now receives data over bluetooth via a bluesmirf (which needs 5 volts). the atmega 168 chip then sends instructions to 2 stepper motors (each one a 3.15v stepper motor, rated as 1 amp per phase at 3.15 Ohms per phase - a Sanyo Denki 103H546-0440). the stepper motor instructions go through a ULN2803 Darlington Array. so typical instruction "turn motor A 10 steps anti-clockwise" and "motor b 20 steps clockwise". All good.
But how to power this set up...
I should say that I want to use rechargable batteries with long life, and physical space for this set up is limited. I am currently using the 5 volt regulator as suggested by Tom Igoe.
questions: 1. I presume I should have two separate power supplies: 1 for the ATMEGA168 and bluetooth chip, and 1 for the stepper motor. 2. For the ATMEGA and bluetooth chip, I'm thinking of either getting 6 rechargable AAs (NiMH with 2700mAh). Is this a good idea? Is there a 'smaller' solution. 6 AAs is actually quite big for this application. 3. For the stepper motors, I'm thinking of getting 4 rechargable AAs (NiMH with 2700mAh). But again is there a smaller solution (I know the stepper motor says 3.15v but i'm advised that i should give a bit more power - there's a fair bit of torque required on this thing). 4. For the stepper motors, I've used 4 ordinary (duracell) AAs and noticed that they get pretty hot quite quickly when powering the stepper motors. This is perhaps unsurprising given that each motor is rated as 1 amp per phase and is driven by exciting 2 phases at a time, and although the motors are given the instructions 1 after the other, I presume they are both 'energised' at the same time. This means that in fact there is a fairly bit 4 amps being drawn out of that battery. Is this correct? Is there a better way of doing this?
Many thanks in advance for all help / assistance. it's greatly appreciated.