T&L Publications

evahle wrote:I really want to stay with non-programmable ICs for this one.

I believe that so many beginners(and amateurs) would like to stay away from programming to start with.

Why? That's a painful limitation.

Do you have any recently purchased electronic
equipment (that may be found in a retail store)
that doesn't use a uC (or derived technology such
as COB or ASIC)?

Just catching up on this thread and found it is similar to a project I am just thinking about. I too want to be able to control 1000+ LEDs. The project goal is to control a high number of single color LEDs, such as blue, to mimic rain drops falling down a window pane.

I am still new to ICs (and not strong in electronics) yet am not afraid to get my feet wet with them or programming. I have been doing a lot with TLC5940NT (Datasheet: http://focus.ti.com/lit/ds/symlink/tlc5940.pdf) along with an Arduino. Great driver overall, yet only 16 Channels. I can daisy chain them and address a large number, yet it's not clear to me if there is a limit to the number of TLC5940NTs I can chain. Also I don't think they are too beneficial for multiplexing.

Pros and Cons to trying to use them to reach 1000+, would need 63 of them and that's a lot of wiring.

I wanted to see if you found any other ICs in the last 2 years that might have worked better or you might suggest now.

If you want 1000 led's turned on sequentially use 2-16 pin processors linked to provide 32 separate outputs and wire all the leds in parallel banks of 32 with a common for each of the 32 led banks. Then use 2 more processors to ground each bank in sequence. (32 X 32) = 1024! Creative use of output expansion chips would reduce the processor count. Google for LED Display strobe techniques. The 7 segment display is often used with this technique. Load the desired character segments, directly or through an encoder. turn on the common for LED#1, turn of fthe common, load the next character, turn on the common to #2 and so on. Do it fast enoughthe LED's look like they are on all the time, not strobed. You will not need a 1000 port chip or as was mentioned in a previous post a single pole thousand throw switch!
Len

Lenp, makes total sense now.

I was thinking too straight forward. I will have to investigate if the TLC can do LOW versus HIGH so that I can control the common grounds as you suggested. Thanks a bunch! Will starts small and test a 16 x 16 matrix first.

This thread may no longer be active but has lots of good ideas. My suggestion would be some 4514 and 4515 chips. Have one drive the horz. lines and the other the vert. Add 16 Rs and some counters or whatever And you have a big matrix thats fairly easy to wire up. (get the HC parts for 20 mA at 5V.)

Einar M wrote:This thread may no longer be active but has lots of good ideas. My suggestion would be some 4514 and 4515 chips. Have one drive the horz. lines and the other the vert. Add 16 Rs and some counters or whatever And you have a big matrix thats fairly easy to wire up. (get the HC parts for 20 mA at 5V.)

Actually I'm still watching my original post on this project. I'm glad you've been trying to come up with something without processors (as I originally asked for). If we use processors and you know how to program them, the project becomes easier of course. I can do both, but I was wanting to get beginners and amateurs to want to join in on this project, and later start using processors to simplify the whole thing. I guess I'm just a teacher at heart.
Anyway, thank you!

Good to hear back from you. Your idea was inventive and should get the prize for fewest ICs. Often the simplest circuit invovles finding the right ICs. There is nothing creative in my suggestion. The '4514 is a 4 to 16 decoder with active high outputs and drives LED anodes and the '4515 is the same but with active low outputs and drives the cathodes. A '4040 counter would provide the input ( but they have data latches making them perfect for uCs too). A schmitt trig such as '14 or '132 would form an osc and the two inverters needed for a 32 by 32 array. Since 74HC family parts work from 2 to 6 volts we can get away without current limiting Rs by dropping the voltage below 3.3V. So a 1024 LED system would use 6 ICs, one R and C for an osc , and a couple of bypass caps ; a total of ten components. Power could be a 3V battery, or a wall wart ( of any voltage ) with a resistor to control current ( V+ - 3 / .01 ) and a zener for safety ( anything from 3.6 to 5.6 V ).

Wow, this is an old project, but still a goodie! A schematic is in order I think.

Ok, here is the final schematic to the 1,000 led (one led on at a time) sequencer.

has anyone thought to just daisy chain a bunch of old school 4017 counter chips ?
i did this with a down and dirty clock i built, it sampled the 60Hz line frequency. was really good, til a CFL light got near it, or anything else that emitted a lot of EMF, then it went into warp time.lol
.
. . .

Hi,
A better knowledge of the features of the LED and circuit, which can lead to efficiency improvement and powerful design tools. It is found a detailed way to describe something of the LED. This is very valuable information for the design process https://www.kynix.com/Blog/397.html

If you know more about it, you will make a better result of what you want, hoping it can give you a little help.

Sincerely,
Leo

I'll vote for a 1000 position, single pole rotary switch with a pulley.and ....Ooops, showing my age again!
Really though, in the days of yore, theater marquee lighting was operated by motor driven switches, and I'll just bet the RFI was splendid!

That would be an interesting looking switch. Haha.
I've seen (on tv) a board with lots of nails in a row that they'd slide a wire across, to fire small explosives to imitate a machine gun. Now I'm showing my age too. Haha.

you think that is something, try working on the electro mechanical rotary ratchet switch units on a old pinball machine.. or Jukebox..Phuuuu ! ! !

Naw, go work on a Stroger line switch, a step by step office or a crossbar at the ancient telcos.
It's click, clack...click,clack...click,clack...click,clack...then silence then Alarms!!