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I have the Arduino UNO rev3 board, a 5V 20 x 4 LCD, and 5V Parallax Ping ))) wired together on a breadboard.  I want to have a portable and/or external power supply to drive the UNO, LCD, and Ping.  I currently use a USB connection that supplies 5V.  Is this enough to drive all these devices?  It currently runs fine, but want to make sure everything (esp. the Ping) gets enough juice.  I'm in the market to purchase/fabricate a car adapter and an external battery.  Any suggestions in regards to how much voltage I need and how I can acquire an external power source?

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USB gives you 500mA of current.
Might be enough - check the specs of your parts.
This 4x20 display for example
http://www.newhavendisplay.com/specs/NHD-0420DZ-FL-YBW.pdf
needs 5mA to run - but 150mA for the display. How bright will you run it?

I don't have the Ping spec handy, can't imagine it  uses very much current tho.

Can probably find a car cell phone charger/similar to use as a car power adapter to feed the arduino.
Something that puts out in the 7.5-9V up to 12V range.

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I don't have the Ping spec handy, can't imagine it  uses very much current tho.

35mA (max)
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Thanks for the replies.  I was doing some digging.  I found that most USB car chargers do 5V.  Having a hard time finding one that does more.  Might have to stray away from a USB based one, find one that takes center core, and maybe adapt the tip if needed.  I'd preferably like to pick one up from amazon.  I have free 2 day shipping through their prime program and I'd like to have this adapter ASAP.  If anyone could help me find one that would be very helpful.  I'll keep looking in the meantime.

Also, any suggestions about making a portable battery pack for this setup? 
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Thanks for the replies.  I was doing some digging.  I found that most USB car chargers do 5V. 

Power, Voltage, and Current are all different (but related) things. 

Most USB-based supplies (incorrectly called "chargers") are 5V.  What you need to pay attention to is both the Voltage and the Current rating.  Your Arduino needs about 30mA.  The Ping is 35mA.  Your LCD is about 160mA.  Whatever supply you choose needs to be capable of suppling at least 250mA.  (Most USB supplies are designed for >500mA).
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http://www.amazon.com/PowerLine-000mA-Universal-Adapter-Compatibility/dp/B0042X8XOQ/ref=sr_1_2?ie=UTF8&qid=1334550947&sr=8-2

I found that guy.  Up to 2A, selectable voltage, and variety of tips.  I think this would be good for this application and others as well.  What do you fellas think?
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Looks like it could work.
Can't tell if one of the tips is 2.1mm inner/5.5mm outer.
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Did you order already?
If not, check this out, $5
http://www.allelectronics.com/make-a-store/item/APC-8/CAR-CIG-LIGHTER-MULTI-VOLTAGE-ADAPTER-800MA/1.html
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Thanks for the link, but I already ordered what I found along with an AC adapter version for the house.  Normally I'd do more shopping around, but I need these adapters ASAP and Amazon offered them at an OK price and free 2 day shipping.  In fact, they should be here within the hour  smiley-grin

The main reason I'm getting this is b/c my Ping sensor is maxing out at 144 inches with and without a parabolic reflector that claims to extend the range.  I was concerned that maybe my setup wasn't getting enough juice.  I've already contacted the developer of this on Parallax's forum asking if there's a problem with my code (that I found).  Has anyone had any experience with this reflector and Ping?  Below is a link for the reflector

http://www.gadgetgangster.com/find-a-project/56?projectnum=361
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