[TriEmbed] Voltage regulation for battery driven mobile robots

[Scott Hall]

This is where we could benefit from the experience of the robotics club guys
(TAR - Triangle Area Robotics).

You will want to power the teensy on its own, not through the power pins on a R-Pi.

Circuit Cellar Magazine last August & September published a Raspberry-Pi I/O
board that is far superior to the Gert Board and its like, but its shares one
basic element:

They have their own power connector, and regulate that with a switching 5V
regulator and a separate 3.3V regulator.  That latter they connect to pin-1 of
the GPIO connector to power the R-Pi - the USB power is never involved.

If you are not using the 5V supply for anything beyond the motors, consider this
6V regulator instead
(https://www.commonsenserc.com/product_info.php?products_id=51)  -- that'll get
you more torque out of your motors, and constant voltage regardless of the
battery level.

On 01/20/2014 12:14 AM, Charles West wrote:
> Hello,
>
> I'm building a mobile robot from an RC tank.  I'm hoping to have a Raspberry
> Pi with a Webcam, Wifi dongle and speakers for the top layer, connected via
> USB to a Teensy 3.0 board (3.3 volts), which will be doing PWM with 2
> H-bridges to control the motors and feeding back data from 3 HC-SR04
> ultrasonic sensors (5 volts).
>
> The motors/batteries are suppose to be at 6 volts.  I think I could boost that
> to as high as 9 volts without problems (though it will oscillate as the motors
> are used).
>
> The Teensy can be powered from USB from the Raspberry Pi and will just be
> switching transistors (so the current draw shouldn't be much).  It looks like
> most everything else besides the motors will be running at 5 volts.  I could
> just use a linear regulator, but with the Raspberry Pi and accessories I think
> the wasted power could be substantial.
>
> I could use a switching regulator, but the ones I've seen so far seem to need
> a lot of external components (this is mostly on breadboard at this point).  Do
> you guys tend to use complete PCBs (like this one:
> http://www.ebay.com/itm/171193232080)?
>
> This is my first battery operated project, so I don't really know the common
> solution here.  If I may ask, what would you advise?
>
> Thanks,
> Charlie West
>
>
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-- 
Scott G. Hall
Raleigh, NC, USA
ScottGHall1 at GMail.Com

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