[TriEmbed] Voltage regulation for battery driven mobile robots

[Pete Soper]

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)?
>
These are great. You can get them to buck (switch to a lower voltage) or 
boost (higher) and the super cheap ones will deliver the few amps 
reliably if you pay attention to heat sinking.

PTC self-resetting fuses 
<http://www.newark.com/webapp/wcs/stores/servlet/Search?catalogId=15003&langId=-1&storeId=10194&categoryId=800000004763&st=ptc&pageSize=25&showResults=true&pf=810022127> 
can be your friend too. These will handle the situation where you 
accidentally short out your battery after jumpering the fuse holder 
after the last fuse was blown... But put this someplace where it's 
approx 100C temperature while open won't be a hazard (especially for 
fingers at the "I wonder if the fuse has opened?" moments!)

-Pete

> 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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