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<div class="moz-cite-prefix">On 01/20/2014 12:14 AM, Charles West
wrote:<br>
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cite="mid:CAGojqS=iHWjXhAxPBz8ZwgP5NH7==QTXcCeO9xWrUsn9D7MeNg@mail.gmail.com"
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<div>Hello,<br>
<br>
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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).<br>
<br>
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<div>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).<br>
</div>
<div><br>
</div>
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.<br>
<br>
</div>
<div>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: <a moz-do-not-send="true"
href="http://www.ebay.com/itm/171193232080">http://www.ebay.com/itm/171193232080</a>)?<br>
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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.<br>
<br>
<a
href="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">PTC
self-resetting fuses</a> 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!)<br>
<br>
-Pete<br>
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cite="mid:CAGojqS=iHWjXhAxPBz8ZwgP5NH7==QTXcCeO9xWrUsn9D7MeNg@mail.gmail.com"
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<div>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?<br>
<br>
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Thanks,<br>
Charlie West<br>
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<br>
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