Hello, i am trying to make a RGB coffee table.
and i saw a lot of posts around here suggesting daisy chaining TLC5940.
i was just wondering, what about TLC5947 or something else
Is it not 24 output (instead of 16 in TLC5940) and cheaper too?
or is there some things that TLC5947 can't do? :-?
any help/ input would be appreciated.
The 5940 is available in a DIP package, making it friendlier to work with. You'll have to play with surface mount soldering to work with the 5947 it looks like.
o! i see
how do you know/check if it's DIP or surface mount? :o
o! okay, i see it!
i have to look for DIP and not QFN or HTSSOP
thanks!
Maybe you want to be looking into something like the constant current M5451 chips.
30 outputs per chip 
See this for info of some being used:
There are other pages on his blog that will probably be more helpful that that one I linked though.
Mowcius
aw, i think they stopped making M5451, or else 30 output sounds awesome.
For an easy way .. check these out too.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1275457576/0
I have used 595s, TLC5940s and these. These LEDs have built in IC's and they are daisy chained / wired already.
If you want to get to "end of job", these are an easy built. * Then you get to work on the programming side.
If you are more interested in the learning process the TLC or other cihp with PWM control built in is best. The 595s can be used to make software PWM .. but it takes alot of them and quite a bit of the processor. So you are on the right track looking at shift registers with built in PWM control.
o, hm! thanks!
i think i came across those once!
they just seems too expensive to me, $2 an LED?
it would cost me well over 100 to make a 8 by 8 coffee table.
great suggestion though, maybe if i can't figure out this 5940s thing, that can be an option.
Check on eBay I can't remember the seller but it's a USA seller and have had great success. They even send free resistors :).
If you want TLCs or similar, I have found very low prices at this place (like 1.80 for TLC5940s while others are much higher).
If using TLC5940s you will want to get common anode LEDs unless you are going to multiplex (see 112 RGB table on this site for details on how to multiplex and reduce the number of chips needed).
I suggest already diffused LEDs .. but note that most will still need some diffusion .. except maybe the 10mm diffused (at .50 each + wait from china via e-bay).
Also you may want to check out the TLC5941NT chip as well.
If your looking at cost here are some basic numbers:
Chips:
TLCs * 3 = 16 LED
16 LED * 4 Sets = 64 LEDs
3 TLCs * 4 Sets = 12 in TLC or $24 in chips at 2 bucks each and I have seen people talking about paying 4 or 5 bucks a chip regularly.
LEDs
You will want extras and can't buy a 64 pack in bulk, you are looking at a 100 pack most likely on e-bay.
Prices are about $37 bucks for 100 common anode diffused on ebay and about $13 for non diffused.
So your minimum cost would be $24 (plus shipping) for chips, figure about $30 after shipping. So $43 roughtly for non diffused LEDs.
Next up is saving yourself the diffusion, your at $65 or so (plus boards) shipped.
Next up is saving yourself the board building time, your at $120 shipped (from down under) for 64 naked 15mm SMDs.
E-bay is a good place to get LEDs, but not the TLCs (generally).
Happy RGB tabling Look forward to seeing your end results.
whoa. marklar, thanks for listing it out, you're the man.
i actually didn't realize it could get so expensive.
hmm, i guess go the cheapest rout with just a dozen TLC + 100 non-diffused. $43, that's cool.
maybe if i just get the table / glass frosted enough or play with the distance, it would come out diffused enough.
;D okay, now i think i know what i need. time for online shopping.
thanks everybody!
I'm not sure they have stopped making the M5451s.
If you look on farnell, some are no longer manufactured but they are 'waiting for delivery' on some from Micrel.
I would search around a bit, maybe send Andrew Stone an email (from the site I linked). He might be able to tell you where you can get some (or maybe sell you some).
Mowcius
FYI: Check the differences between the TLC5941 and the TLC5940 .. may be happier with the TLC5941 per some posts, but I have not used that chip yet.
Also if you are really worried about prices and you want the most least expensive option, knowing there is alot more work involved .. the 74HC595s can be had on e-bay for about 40 cents each.
For these you will want the common cathode RGBs and you need resistors added. Whereas the TLC versions do the resisting for you, therefor you don't need that component. Also note that you will have to manually do PWM where the TLCs do this for you as well. So when you boil it down .. for 40 cents you get 8 pins.. double that to 16 to match the pins on the TLC and your at 80 cents. For only twice that at 1.80 per chip on avnet .. you get a much nicer chip .. a TLC version.
TLC5940 disclaimer:
But note I had color correction issues with the TLC5940 but may be isolated. Why I suggest the TLC5941 as I think it may need fewer pins, has more umph at 80ma and no color correction eeprom to have to deal with when you don't need it for those RGBs.
74HC595 disclaimer / details:
While for the reasons mentioned above, I don't suggest this route, it may be the least expensive way to get started.
Also note if you are using the 74HC595 and you need resistors to make sure you purchase the LEDs from someone that has free R (resistors) and make sure they either say for both 12v and 5v or you contact them in advance to assure you can get the 5v resistors and then make a comment to that affect on your purchase. Getting 300 of the wrong type of resistor can blow your project or at least timeline.
Getting the 74HC595 chips:
I have bought from this supplier twice with good results.
10 (packs) * 1.20 = $12
9 * .2 = 1.80 + 5 = $6.80 shipping
so for under $20 you can get 50 of the 74HC595. (40 cents each)
well, i have some 595 lying around already.
but it just sounds like insanely tedious programming when it's RGB.
o, so you DON'T really need color correction for RGB? O.o
and is there a difference between like NT and NTG4?
I could not tell the difference, however they should be functionally the same from a pin out and use perspective.
I did find this .. just note that answer.com answers are best digested with a grain or two of salt.
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Regards
For all those who are talking about how expensive the TLC5940's are, Texas Instruments has a "samples" program for these, you get get up to 5 free with free shipping. check out the site www.ti.com