LEDs without the use of current limiting resistors

but im pretty sure everyone here knows about that stuff,

I wish.

Oh poor misguided mike, he just doesnt understand the real world, and clings to his tired old beliefs, insulting people that disagree with him :frowning: (see how lame and unproductive those kinds statements like that are?)

I guess you forgot(or you chose to ignore that...) that I had mentioned that Im running 2 cubes 24/7 and I have a 3rd that I run occasionally, and that they have been running for months (since the beginning of november I think.) If you dont like the 2 as a small sample size, consider that each cube has 192 LEDs maybe that size is big enough for you?

This cube isnt really my design, I found it on the internet while struggling to get my other cubes working (which by the way, are still unfinished, and not working, but yet these cubes are running strong, so one advantage to this design is that its working now, not some mysterious point in the future. This design has some advantages over other designs, its easier to build, has less parts which means less places for mistakes. Those may be unimportant to you, but to someone that wants to program an LED cube, it is important.

It may turn out that it takes 5 years before this cube fails, a cube with resistors may only last 1 year more, or it may last 10 years more, but one thing we know, they will all fail eventually, resistors will likely delay it, but can not prevent it.

Regarding dimming, clearly there is no way I will have expensive equipment to try to view any damage, the closest I can get is optical magnification, which may not be good enough, but what I do have is a fat sack of LEDs and I can compare the brightness of a new LED to one that has been running for months.

Where do you get resistors for less than one cent each? I get them cheap on the internet, and they are 2-5 cents each, in packs of 100 or more. LEDs arent very expensive either. My whole cube and arduino costs about $25 each, its a fairly inexpensive test.

It may turn out that I can extend the life of the cube with a few resistors, but as it is, its looking pretty good without them.

The reason casino owners and lotteries make money is because people are greedy, not uninformed.

The reason casino owners and lotteries make money is because people are greedy, not uninformed.

I disagree - greedy AND misinformed.

Hippynerd - I am truly sorry for knowing stuff that you don't know. I will try and forget it all so I will be as good as you. Please forgive me. I will now try and get drunk in an attempt to kill of more brain cells in order to stop me being old, but I might be some time.

Ha ha, good luck with that. I never asked for an apology, but its nice that you offer one. I forgive you, but please do try to make valid points without resorting to insults.

The reason casino owners and lotteries make money is because people are greedy, not uninformed.

Lets see.
You can't win if you don't play.
You lose if you play.

I guess there is no way out of this delima. :smiley:

Hippynerd:
Where do you get resistors for less than one cent each? I get them cheap on the internet, and they are 2-5 cents each, in packs of 100 or more.

Pretty much anywhere. Here's some 10K resistors from DigiKey for 0.2 cents each at qty 100:

As an aside, this is easily my favorite thread of the new year.

magagna:
As an aside, this is easily my favorite thread of the new year.

Not one mention of Sparkfun's place in all of this yet (OP's example was written by a Sparkfun employee).

Sparkfun did sell a no-resistor-multiplexed-led display, their 7 segment serial display. They updated it. Spot the difference :wink:

Oh poor misguided

Your goal is noble.

However, at some point, you have to recognize an individual's right to remained challenged.

It makes you happier, and it makes the people who refused your help happier too.

Win-win.

Sparkfun did sell a no-resistor-multiplexed-led display,

How "misinformed" they are, :slight_smile:

magagna:

Hippynerd:
Where do you get resistors for less than one cent each? I get them cheap on the internet, and they are 2-5 cents each, in packs of 100 or more.

Pretty much anywhere. Here's some 10K resistors from DigiKey for 0.2 cents each at qty 100:

http://www.digikey.com/product-detail/en/1622826-4/A106045CT-ND/3477682

As an aside, this is easily my favorite thread of the new year.

Those are 1/16w 0402 smt parts, I actually have some of those, have you ever tried soldering them?

I should look over digikey and mouser more often, but I find them those sites a bit overwhelming.

How about regular 1/4W carbon resistors then? $0.01 each for 10-lots.

I don't like what Tayda did to their website - the menu shows up on the left, while anything selected now shows up underneath it with a big empty space next to the menu.
My screen is set to 1280 x 800 - anyone else seeing the same?

Looks to be IE9 thing - don't see the layout issue with Google Chrome.
IE9 didn't used to do to that, this is fairly recent.

works fine for me

edit: firefox

CrossRoads:
How about regular 1/4W carbon resistors then? $0.01 each for 10-lots.
http://www.taydaelectronics.com/resistors/1-4w-carbon-film-resistors/10-x-resistor-220-ohm-1-4w-5-carbon-film-pkg-of-10.html

I don't like what Tayda did to their website - the menu shows up on the left, while anything selected now shows up underneath it with a big empty space next to the menu.
My screen is set to 1280 x 800 - anyone else seeing the same?

Looks to be IE9 thing - don't see the layout issue with Google Chrome.
IE9 didn't used to do to that, this is fairly recent.

On IE 8 it works ok, with chrome when you mouse over a menu category on the left the submenu displayed is 95% hidden behind whatever picture is displayed in the middle of the screen, just that very edge of the submenu can be seem. I just sent them an email about it. I'm at 1280x960 display.

Lefty

CrossRoads:
How about regular 1/4W carbon resistors then? $0.01 each for 10-lots.
http://www.taydaelectronics.com/resistors/1-4w-carbon-film-resistors/10-x-resistor-220-ohm-1-4w-5-carbon-film-pkg-of-10.html

I don't like what Tayda did to their website - the menu shows up on the left, while anything selected now shows up underneath it with a big empty space next to the menu.
My screen is set to 1280 x 800 - anyone else seeing the same?

Looks to be IE9 thing - don't see the layout issue with Google Chrome.
IE9 didn't used to do to that, this is fairly recent.

I think thats where i got the ones am currently using. after shipping their costs go up 2-5 times depending on your patience.
Standard 7 - 16 Days $1.08
Economic Express 6 - 9 Days $4.08
DHL Express 2 - 4 Days $16.00

I can also get them from thaishine, for a few bucks with 4 day shipping. Its much better than the local prices (about a quarter each), but its no 10 for a penny.

I've only used the slow/cheap shipping. I stock up when I buy, $30-40 worth of stuff at a time, so shipping becomes a small part of the total price.

Hippynerd:
I should look over digikey and mouser more often, but I find them those sites a bit overwhelming.

I agree they can be daunting at first but they're manageable. I much prefer DigiKey's interface; I find it the easiest to use. Many times if I get something from Mouser, Newark, etc. I'll find it on DigiKey then cut & paste the part # at the other sites.

I start by searching for as close to what I need as possible, e.g. "atmega328p-au" or "1/4 watt 10k resistor". This generally does a good job of getting close.

Next I check the "In Stock", "Lead Free", and "RoHS Compliant" boxes and search again; there's usually no point in searching if they don't have it in stock and the other two seem to help whittle things down further.

Next I start going through the search boxes like "packaging" or "height", etc. for things I know I want, e.g. a specific size or footprint and click "apply filters" each time.

When the result list is a reasonable size I sort by "unit price" and buy the cheapest one (unless I know I'll eventually need a lot of the part, in which case I give "quantity available" some weight).

Having said all that, I try to do as CrossRoads says and batch up purchases at one of the Chinese companies; this is usually the overall least expensive option.

mousers interface is down right frustrating to me, but its better than it was?

digikey is overwhelming until you get it, then once you do you can take an idea like "i need a shift register" and filter it down to the cheapest one in the quantity range you want, while meeting your requirements with two - three filter passes, its almost an art

I don't buy Chinese or e-bay generally (WS2803 is one exception), except for iteadstudio.
dipmicro.com in Canada/Western NY, taydaelectronics in Thailand
and Digikey, Mouser, Avnet, Pololu.
Sometimes Newark. They have eagle symbols for some parts too.
Phoenixent.com for strip sockets & headers & wirewrap stuff.

I use these sources for their repeatability.

Digikey/Mouser both irritating digging down trying to find things like header strips. I buy that kind of mechanical stuff from pololu and phoenixent instead.
For resistors, caps, transistors, diodes, surface mount, digikey is the best.
Mouser has best prices on Atmel parts.
Avnet for TPIC6x595 shift registers.

I usually stick to digikey and mouser for small quantities

I got to give props to arrow and avnet, they are 2 of our suppliers at work, and hey, they buy me nice lunches hehe, and both have good support even if they dont know who you are

DK on the other hand sent me 250 .1uF 805 caps, which were suposta be 5Amp rectifier diodes in a SMC package (for those not familiar with surface mount packages its a grain of rice vs a jellybean, never mind its totally the wrong component), and I got a deadline on (next)Tuesday ... I had to get bitchy with them and reorder somewhere else cause a couple weeks later and people still cant find info on the mix up is not cool, so they are a bit on my list right now