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Topic: Not enough power. 6 leds in series. Can I? (Read 1 time) previous topic - next topic


I have found that I can only power 3 LEDS with my MEGA board.
Anything over that seems to be past its limit.
Is there anyway that I could power 6 LEDs at the same time, with an external power source?

Im just scared because I dont want to blow out my MEGA board in the process.

Would appreciate anyone explaining if its possible and what I need.

About my project.
I have 200 LEDs I want to power in a matrix.
But I want to group them in different configurations, and have them in groups of 6 LEDS connected in series.
thats it -

this is how I understand the program so if someone can help make it happen, perfect.
Thanks in advance.


It is not the power that is lacking it is the voltage. Depending on the colour of the LEDs the minimum voltage needed changes. Look at the forward voltage for your LED then multiply that by seven to give you the minimum voltage you need for the LEDs and the series resistor. Then use a transistor to switch that. Don't forget the resistor on the base of the transistor.


200 LEDs, use 4 MAX7219, LEDs are wired in groups of 8, can turn on/off any LED(s) in any group you want.
For example, here's 256 LEDs that can be accessed as described.

This breakout board I offer makes it easy to wire up individual LEDs if that's your plan.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


thanks grumpy mike -
Probably would have forgotten the resistors.

Never thought of using a transistor.  Ill read up on that.

That should take care of the hardware side of it.
Anyone got any good articles or examples of how I would program it - because for some reason I still dont get how shift registering works.

I just cant seem to grasp how the program can recall the address of say the 109th LED out of the 200th LEd setup Im trying to make.


You haven't really told us what you want to do... And you certainly never talked about shift registers before so how are we supposed to know you wan to use them? If you want software help, tell us exactly what you want to do.
Use fricking code tags!!!!
I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

NEW Library to make fading leds a piece of cake


I have told you in another thread you can not just change one shift register pin. You change the bit in the data you send out to them.


Thanks crossroads.
Im kinda interested in your 64 LED setup.
But Im scared Im going to spend too much time trying to figure out how to program it.


But I'm scared I'm going to spend too much time trying to figure out how to program it.

That's called programming. :smiley-roll:


Yeah I know, its programming.
But Im really not a programmer, Im more of a hardware guy.
I like cars, and building computers and putting them together.

My brain can sort that stuff out.
Programming gives me alot of problems.
Some peoples brains just work different then others....
but thats not a bad thing.


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