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your supply may be capable of 5V, and a gazillion mA
over current wo'nt burn the circuit??
for example this adapter (photo) will be allright to use, BUT we should use a regulator for the voltage (because it's 9-12V) ??





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Look at the top right - X1 is barrel connector, D1 is reverse polarity protection diode, U1 is the onboard regulator.
The voltage before the diode should be ~7.5V, the voltage after the diode ~6.5V, and the regulator will output 5V.

i did understood the sketch, well sort of,iv'e couple of questions for that aswell but not now. What's more important is that i still cant understand how should i connect everything, cause u said: "U1 is the onboard regulator" so - i shouldnt add a regulator? and if i should does it matter which 5V regulator (can i use this 7805 Voltage regulator?) ?
does the diode is just optional?
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Set your adapter for 7.5V, center positive, and stick it in barrel jack connector.
Measure the voltage at Vin.
Connect your LED anodes to Vin adjust your current limit resistors to match.

That's it.
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stick it in barrel jack connector
Do you mean the arduino jack connector ? the one that's near the usb?
or do i need to use an external one?

and i still cant understand how should i connect everything, cause u said: "U1 is the onboard regulator" so - i shouldnt add a regulator? and if i should does it matter which 5V regulator (can i use this 7805 Voltage regulator?) ?

thanx for the patience smiley
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Yes, the black round connector near the cornef of the board.
No additional regulator needed with the adapter you showed. Set it to 7.5V, center positive, and plug it into the board.
Measure Vin.
Connect Vin to your LED anodes, and use suitable resistors between the cathodes and the collector of the transistor.
(~7V - Vf - Vce)/.02 = resistor

ex. (7V - 2v - 0.7V)/.02 = resistor
« Last Edit: September 18, 2012, 09:11:53 am by CrossRoads » Logged

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- oh, so if it's (barrel jack connector) count as an external supplier, can i use a USB as well? (not that im goingto its just for understanding)
- and how much voltage can the barrel jack connector "take"\handle to the VIN pin?
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1.Yes. USB only supplies 500mA. DO NOT connect you LED Anodes to power them.

2. Up to about 12V. More than that and the U1 regulator may get pretty (quite) warm. That's why I suggested 7.5V.
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ok lasts questions smiley
- im not sure what did u mean with this-
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DO NOT connect you LED Anodes to power them
- again about the NPN, i found some cheaper one's and i want to be sure they gonna be suitable:

http://www.taydaelectronics.com/hit8050-transistor-npn-20v-0-7a-to-92-hit8050ctz.html
http://www.taydaelectronics.com/ksp13-transistor-npn-30v-0-5a-to-92-ksp13ta.html
http://www.taydaelectronics.com/ktc1027-transistor-npn-120v-0-8a-to-92l-ktc1027y-at.html
http://www.taydaelectronics.com/ktc3202-transistor-npn-30v-0-5a-to-92-ktc3202y-at.html


-Just to make sure, (and to expirience the software ) this is how i am gonna connect everything:
the 9V battery is insted of the ac/dc adapter-couldn't find it in the software

http://sphotos-g.ak.fbcdn.net/hphotos-ak-ash4/s720x720/418525_4403553004146_1268536174_n.jpg



 by  the way if anyone interested this is the software: http://fritzing.org/  its realy easy and u can do sketch/prefboard as well smiley
thanלss smiley)
« Last Edit: September 19, 2012, 02:36:29 pm by Justniv » Logged

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I meant do not connect your common Anode to 5V on the arduino to power. You will need up to 600mA if all LEDs are on, and USB can only supply 500mA.

I don't care for fritzing. Cannot tell what is hooked up - for instance, which the Base-Emitter-Collector pins on the transistors?
Which is the anode on the LED? Is the middle resistor connected on its right side?
I'll take a real schematic anyday.
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ok sorry. what software did u use to make the sketch?
-can you please approve the transistors...?
- i got to the conclusion that im gonna do this project and use an atmega328 on a prefboard - like here:  http://arduino.cc/en/Main/Standalone
so, i just wanna be sure that its gonna be ok to connect an ac/dc adapter (7-12V) straight to it
thanx smiley
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The first & third are adequate.
2nd & 4th are too low in current capability. (0.5A).

I use expresspcb.com to make schematics for posting here.

7-12V adapter will have to be regulated by 7805 type regulator.


* Barebones_arduino.jpg (62.62 KB, 960x720 - viewed 18 times.)
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oh i thought that NPN with 0.5A collector current will be ok because we r using only 0.2A. so i gusse the bigger the margin the better.
- and yes, by the link i posted (http://arduino.cc/en/Main/Standalone)  the r using an 7805 regulator for power supply.
CrossRoads Thank you very much, you helped me a lot and i learned a lot ! thanks for the patience smiley
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I thought you needed 600mA - I might have posts mixed  up.
If you only need 200mA they should all work.
Let us know how the project goes...
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each transistor need 200mA, thats mean 3x200=600mA (your calculate haha)
i will let you know when i finish, now i need to order everything...
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