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[on:]

I'm wondering if there is any simple way to make a solderless LED matrix. I made a simple 2x2 matrix on my breadboard, but I can see that anything bigger will get to be pretty complicated in such a small space. Ideally what I would like is jumper cable that are in a y or some other sort of connector that would allow me to attach multiple jumper cables, but I can't seem to find such a thing anywhere. Does something like this exist?

[Reply #1 on:]

Buy more/larger breadboards and tie them together.

[Reply #2 on:]

Not really the ideal solution because:
1. Price.
2. Flexibility. I'd like to have the LEDs a fair distance apart. I could use one breadboard for each LED, but having 25 breadboards for a 5x5 matrix seems a little unreasonable.
3. Breadboards are only connected in one direction (ie rows) whereas a matrix has rows and columns. You could make this work, but it becomes a complicated mess pretty fast.

I wonder if a metal clip of some sort might work? Maybe this? http://www.ebay.ca/itm/33mm-Silver-Prong-Metal-Hair-Alligator-Clip-20PC-Zh49-/320997036427?pt=LH_DefaultDomain_0&hash=item4abcea118b#ht_6343wt_1139
Or this? http://www.ebay.ca/itm/100-pcs-Silver-Plated-Extension-spring-connectors-Jewelry-findings-9-3-5-mm-/180991070573?pt=LH_DefaultDomain_0&hash=item2a23e8916d#ht_1560wt_1271

[Reply #3 on:]

So why not wire up a matrix of headers, with pairs of pins that you wire your LEDs off to wherever?
It can end up looking like an 8x8 matrix less the LEDs and you can use an MAX7219 to drive them all.
See the attached - every place you see an LED, put a 2 pin connector.
Now combine the 2 pin connectors into strips of headers, and you have a nice compact 8x16 solution for remoting 64 LEDs.

[Reply #4 on:]

Ya know, I Still dislike looking at a placed Rats Nest drawing... too much like my last job...

Bob

[Reply #5 on:]

So basically build the matrix at the breadboard and then use a 2 pin connector to connect to each LED? I think that makes sense and could be a workable solution. I have a 74HC595 right now, does anyone know if one of them is enough to control a 5x5 grid? If not I might buy a MAX7219.

[Reply #6 on:]

Spend $1.25 at taydaelectronics.com and get a MAX7219, a 30K trimpot, a piece of prototyping board,  and 2x20 pin headers and start building.
Will end up with something way more secure & reliable than trying to do it on breadboard. LEDs too if you need them.
Order today, will have parts in your hand in a couple of days.


"A" 74HC595 is not enough for a 5x5 grid, you need 10 control pins, and that only gives you 8.

[Reply #7 on:]

"A" 74HC595 is not enough for a 5x5 grid, you need 10 control pins, and that only gives you 8.

Okay, thanks. I suspected that from a bit of Googling, but wasn't sure.

Spend $1.25 at taydaelectronics.com and get a MAX7219, a 30K trimpot, a piece of prototyping board,  and 2x20 pin headers and start building.
Will end up with something way more secure & reliable than trying to do it on breadboard. LEDs too if you need them.
Order today, will have parts in your hand in a couple of days.

Would this require soldering? I'm still trying to sort out how all these different components work. I guess I'm not really clear on how the pin headers work.

Thanks for all the help so far.

[Reply #8 on:]

Just enough soldering to hold the corners of the sockets onto the perfboard.
Everything after that can be wirewrapped.

http://www.king-cart.com/phoenixent/product=SOCKETS+WIRE+WRAP+DIP+%2526+SIP/exact_match=exact
I build all my prototypes that way. Minimal soldering, easy & quick to make changes or fix mistakes.

The pin headers are just female headers like on an Uno. Provides an easy way to plug in remoted LEDs.
Can use male header pins too, slide on female crimp terminated wires.

http://www.pololu.com/catalog/product/1901

Make up your own
http://www.pololu.com/catalog/product/1930
http://www.pololu.com/catalog/product/1931

or use pre-terminated wires
http://www.pololu.com/catalog/product/2001
different lenths, different terminations available.

[Reply #9 on:]

Spend $1.25 at taydaelectronics.com and get a MAX7219

$1.25... $1.25!! uk, price about £1.00...

rs components; £11.30
farnell; £14.48

i wonder what shipping is like!!

[Reply #10 on:]

To the US, shipping has been cheap. Last set of parts I ordered was $1.87 for 8 MAX7219s, resistors, and I think aset of one other small thing.
Time before that I bought a bunch of bulky electromechanical parts - pots, knobs, switches, whole mess of SMD stuff. Biggish padded envelope, $8 something for shipping.  Stuff has been arriving from a Colorado address and Thailand, must be some kind of distributor deal set up?

[Reply #11 on:]

That is a ridiculous price for the MAX7219. Well, the normal price is the ridiculous one...but $1.25 is unheard of. Somehow I think that can't last long.

[Reply #12 on:]

Thanks for all the help so far. I ordered a bunch of stuff from Tayda Electronics - great prices. It has arrived, but I ordered some wires from another supplier and they aren't here yet so I can't build it yet. In the meantime I'd like to learn how to use the MAX7219. All the tutorials seem to be about matrixes, but I'd like to start by just controlling individual LEDs as I assume that would be more basic and give me a better understanding of how it works. Any suggestions on good resources for this?

[Reply #13 on:]

Hello dtaylorl,

I am hardly one to give advice with all the questions I ask on the forum  but I have been playing around with the Max 7219 and an 8 x 8 LED matrix and believe me by using the "LedControl.h" library they are very easy to use. Even if you did hook up one LED to the chip what could you do with it, only turn it on and off whereas with a simple 8 x 8 matrix you can turn on whole or part rows or columns, individual LED's  and come up with interesting pattern displays etc. These links will get you up and going

http://arduino.cc/playground/Main/LedControl

http://www.arduino.cc/playground/Main/MAX72XXHardware

http://arduino.cc/playground/Main/LedControlDemos
As I have said I am a rank amatuer at Arduino and by using the Max chip I have amused myself for hours,
Pedro.

[Reply #14 on:]

Great Video, Pedro,. I see you are having fun and getting really valuable experience. Keep it up.
@ CR Those Pololu links were great. Good prices on good jumpers... 22 Ga. Too. Most of those jumpers with the round ends are 30 Ga wire... Caused me a lot of grief before I learned. $10 for 50 pieces is a good price because those last forever.

Bob