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Topic: Arduino circuit/breadboard not working at higher voltage? (Read 7 times) previous topic - next topic

CrossRoads

Why didn't you install the 2 other caps?
And put some caps on the input & output of the regulator.
You should really have a current limiting resistor in series with the LED - you're going to damage the LED or damage the output pin wired up as it is.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

xl97

#6
Feb 18, 2011, 10:08 pm Last Edit: Feb 18, 2011, 10:13 pm by xl97 Reason: 1
thanks for the reply guys..

as I said Im new.  so the 'why' questions should be self-evdident.  =)

just dont have the knowledge/experience to know better/different.

ok.. so I will go back and add in the

* 10nF cap (103) in front of the vRegulator (across the GND and OUTPUT)  BEFORE the  power +/- lines reach it.

* 22uF cap across the 'rails' on my breadboard.. (after the GND/output from the vRegulator)


@CrossRoads-

I guess Im more confused by your comments now?

I see/added in the two missing caps..

but there are two more?  seems like I have 4 missing components from your comments

also this:
"You should really have a current limiting resistor in series with the LED - you're going to damage the LED or damage the output pin wired up as it is."

not really that far along yet.. =(

(knowing how to correctly wire up the leds/components for testing/development..  I really want to get to the code parts of playing more) LOL

I thought the chip was capable of turning on smaller accent leds types without much fV and low mA?..
(but what do I know).. I never know if I have things wired up right/wrong..


to be clear I put the + lead to the chip/pin always,.. and the - to the GND rail..
(not other way around)?

where does the resistor go?  between I/O pin and + lead from led?





Thanks Lefty, FCrossroads..everyone for replying/helping out.


appreciate it. =)

CrossRoads

#7
Feb 18, 2011, 10:59 pm Last Edit: Feb 18, 2011, 11:01 pm by CrossRoads Reason: 1
If you look at any arduino schematic, you will see "large" caps (47uF, 100uF) on the regulator input & output, that was the caps I was referring to. The 100nF goes across the atmega328 VCC & Gnd pins close to the chip itself.
http://arduino.cc/en/uploads/Main/arduino-uno-schematic.pdf
If you look at pin PB5 (19, which is D13), you will see a series resistor with the LED. You want that.
Unless you know for sure your LED has one built in, operating without the resistor will lead to either a damaged LED (cheap) or a damaged output pin(replacement ATMegas ar $5.50 - not so cheap). If your atmega feels hot to the touch when running, that is a sure sign that something has been damaged.
There is also a 100nF cap across Vref to help that keep noise down if you are making analog input measurements.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

xl97

wow..

I barely understood much of that (sorry) I know your trying to help/educate me int he best practices.

That schematic looks foreign to me so far.. =(  although I do understand the D13/P19 reference..

(Im trying to stick with it.. once I do things a few times/repetition.. I understand and feel comfortable..just not there yet) =(

here is the 'fix' I did on both breadboards to stabilize my vRegulators on my projects:






looking at the schematic (again)..

Im thinking you mean the RIGHT side/box/object for 19 (PB5).. not the one on the left? since it goes nowhere?

although I have no clue how to tell or see there is a 'series resistor'...

matter of fact the more I look at the diagram/schematic.. the more Im getting lost.

so to swing back on topic..

I do 'not' see or understand these 'large caps' why or even placement.. vs the caps I just put in place per Leftys suggestion and cobbling it together from the links.

is what I did wrong?


thanks

retrolefty

Almost correct. That larger capacitor you have wired between ground and +5vdc should be changed so that it's negitive lead is still wired to ground as you presently have it, but it's positive lead is connected to your regulator's input pin, which is any of the pins in row two on your picture.

Lefty

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