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(newbie question) energy and power (Read 7822 times)
04/30/08 at 06:14:48

julienb   Offline
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wiring AND arduino owner
France

Posts: 81
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if I can understand well informations & data flows, I have a big newbie problem in my head: power supply  Embarrassed  Grin

on http://www.wiring.org.co/learning/tutorials/diagrams.html  , I can see that components can be powered by the VCC pin 5V.

if I use usb to power the board, can I use VCC pin to power some components?
how many components can i power like that ? the real question is, how can i calculate that?

Embarrassed Embarrassed Embarrassed   Wink
 

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Reply #1 - 04/30/08 at 07:42:15

barragan   Offline
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yes you can, I´ve seen touble when using more that 2 servos for example, but servos are high current consumption devices. I have run applications drawing about 400mA from the USB with many leds. An external power supply is recommended when using motors etc.
 
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Reply #2 - 04/30/08 at 10:05:04

julienb   Offline
Junior Member
wiring AND arduino owner
France

Posts: 81
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hi hernando,

I'll drive around 50 leds.
I'll calculate the right intensity, but as you wrote, I guess it will rock !!

thanks a lot for the answer to the BiggEst newbie!

(I'm waiting for the "making things talk", the book of Igoe ; I ordered it in order to become a smart newbie Wink )
 

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Reply #3 - 04/30/08 at 10:13:41

julienb   Offline
Junior Member
wiring AND arduino owner
France

Posts: 81
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50 rgb leds = about 50 * 20mA .................... = 1A

I hope it could be ok  Undecided
 

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Reply #4 - 04/30/08 at 11:52:18

Vaccumdiode2   Offline
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chicago, IL USA

Posts: 120
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Hello,
              I think 1A is to much to pull through the board.  The voltage regulator on the board is only rated for 1A.  The wiring board itself pull some current.  If you pull 1A though the board it most likely will damage the ragulator.  I nomally put a regulator on each project board I build.  you never want to run a componet at it rating. you want to run it at about 75 to 80% of it's total rating.

 
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Reply #5 - 04/30/08 at 12:34:54

julienb   Offline
Junior Member
wiring AND arduino owner
France

Posts: 81
**
 
ok
I have to dive deeply, cause I don't understand how it goes ...  Embarrassed
 

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Reply #6 - 04/30/08 at 13:14:38

barragan   Offline
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I´ll post a diagram on how to do it. Basically if things are going to use reulated 5 volts you´ll need your external power adapter, an LM7805 regulator (this is a 5V regulator), a 100uF and 2 100nF capacitors for decoupling. I´ll get back to you.
If you need 3.3V regulation circuit it is quite similar, same capacitors but 3.3 regulator like the 7833 or others.
 
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Reply #7 - 04/30/08 at 15:06:07

julienb   Offline
Junior Member
wiring AND arduino owner
France

Posts: 81
**
 
you save me !

I'm waiting for that!

I would like to say that EVERYTHING I'll do will be published !
OpenSource controller is my way  Cheesy

cheers!
 

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Reply #8 - 05/05/08 at 22:27:45

barragan   Offline
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here are drawings for both 5V and 3.3V power regulators.
http://wiring.org.co/learning/examples/powerlm7805.html
http://wiring.org.co/learning/examples/powerlm7833.html
 
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Reply #9 - 05/29/08 at 18:11:38

gokce   Offline
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I was using LM7805 regulators in my project but they are also 1A and in the datasheet it says that they will deliver over 1A if it is well cooled. I tried it and it gets hot pretty easily. I would recommend LM323 if you are going to use around/over 1A. It could deliver 3A. Connections are same with LM7805.
 
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