Help to figure out how to wire a LED array

[OOPS!]

Hi! I am embarrassed to admit I am 64 years old and have scarcely any electrical/electronic experience, save the time I was standing barefoot on a concrete garage floor while dismantling an operating electric clock and touched a 'hot' terminal.
Nevertheless, LEDs are awesome, and I want to get involved in using them. I want to build a small (6" square) LED sign, using 32 LEDs around the perimeter, that will blink at no specific speed, along with 17 LEDs in the center section that would stay lighted when sign is switched "on". I want it powered by a household-outlet plug-in transformer with battery back-up, with a wireless remote off/on switch. I bought 100 ea. 14000-16000 mcd white LEDs that are 3.2 V forward voltage, 60mW 20mA forward current. This is going to be FUN! regardless of how I get there ......... that being said ............ How much trouble am I in? lol
Thanks in advance for any information you will give me toward finding a solution to my project.

 

[bychon]

Sheesh! Wiring LEDs is a lot simpler than building a remote control! I have seen LEDs at Radio Shack that blink at no specific speed. If you buy them, the blinking part is covered. Otherwise, you'll be building a slow oscillator...probably with a 555 chip. The power supply is a whole 'nuther project, too.

If your background consists entirely of, "got knocked on my butt once", you are in way over your head.

 

[TechnoGilles]

First of all congrats !! My 38 yo self en route to 40 is pleased to see we can start learning new things at 64 !! Good for you !!

If you want the perimeter LEDs to blink all at the same time, yep, you should look at an oscillator with a 555 chip. You'll need a MOSFET switch as well cause if you intend to run your 32 LEDs at 20mA, that's 640mA and the poor 555 will not handle that much !!!!

Then, if you add up the current for the other 17 LEDs, your in for a total of 980mA so you'll need, let's say, a 6V power supply rated for at least, say, 1.2A. You could use a LDO regulator to get your 5V logic supply, and a few others to get the 3.2V for the LEDs (avoiding the needs for a whole bunch of current limiting resistors). I like the MIC5209 500mA LDO series.

Like bychon said, the battery backup and remote are another story !! But it sounds fun !! I think I'll have a look at remote circuits !! I'll keep you posted !!

 

[MrDEB]

A ULN2003 comes to mind for controlling all them LEDs. Then one could use the 555 and PWM to manage all that current.
This sounds like a fairly simple design solution.
Will look for a schematic.

 

[nickelflippr]

I would concentrate on the led side of the project and go store bought for the rest. Depending on where you live, a key fob on/off remote controlled relay/power outlet (a wall wart like AC plug) are really cheap at the local hardware or big box store. A UPS plug strip will be more expensive.

 

[audioguru]

Your LEDs have such a high brightness number that I think they are cheap Chinese ones from E-Bay. They are dim old ones in a clear plastic case. They are tightly focussed into a very bright but very narrow beam that cannot be seen if it points slightly to the side and not directly towards you. Modern wide angle bright LEDs would be much better. I am also 64.

 

[OOPS!]

Wow!

Thanks for the overwhelming positive response (and the one other, too! lol. -just kidding. I actually am looking for honesty, and diversity of opinion is ..... uhm .... humbling ..... but I will go with the majority and press on in my ignorance with the hope I may someday know enough to be of help to someone else that is as uninformed as I am now. ) I am really excited to get into this, and you folks have provided me with more info in one day than I have found on my own in a month! Your comment was spot on, though. I did buy cheap LEDs from China. Is that a problem? Where can I read more about those, and how they are processed. Oh! look at the time! I can't write any more now 'cause I gotta go buy more "stuff" LOL! This is gonna' be FUN!!! Thanks to you all again!

 

[OOPS!]

Wow!

Thanks for the overwhelming positive response (and the one other, too! lol. -just kidding. I actually am looking for honesty, and diversity of opinion is ..... uhm .... humbling ..... but I will go with the majority and press on in my ignorance with the hope I may someday know enough to be of help to someone else that is as uninformed as I am now. ) I am really excited to get into this, and you folks have provided me with more info in one day than I have found on my own in a month! Your comment was spot on, though. I did buy cheap LEDs from China. Is that a problem? Where can I read more about those, and how they are processed. Oh! look at the time! I can't write any more now 'cause I gotta go buy more "stuff" LOL! This is gonna' be FUN!!! Thanks to you all again!

 

[Boncuk]

Hi Oops,

here is a circuit suggestion. The board size is 4X4".

Using more LEDs at the same spacing it can be made 6X6".

The MosFet transistors used require no cooling.

Let me know if you want to use more LEDs. Otherwise I'll refine the PCB layout and leave the size.

Regards

Boncuk

BTW, I beat you by four years. Celebrated my 68th birthday a few days ago.

 

[OOPS!]

Thank you, boncuk, for the thumbnail schematics ... and belated Happy Birthday!!
I used the information you gave me, and modified it to accomodate the number of LEDs I wanted, which was different than your schematic. I extrapolated the information you gave me, and I visited my local electronics store that advertises they have what is needed for prototypes. Unfortunately, I missed their somewhat short business hours, and they will not be open again until Tuesday. I plan to go there then, and with a little luck, I will be soldering Tuesday evening!! I can hardly wait!! Thanks again.