How do I control 72 100V 2000MHz EL Wires?

Forum 2005-2010 (read only) Hardware Interfacing
#1

Hi everybody,

I am working on a (rather hasty) project with EL Wires (Light emitting wires), which work with a couple of 100V/2000Hz/250mA inverters. (datasheet of the cables: http://www.elam-lytec.com/pdf/04S_common.pdf, specification of the inverters: http://www.kitelight.nl/var/images/KD15.JPG)

I need to control 72 separate pieces of this wire stuff, with a total length of about 30 meters. These pieces will form 3 digital characters (23 pieces per character) in a distinct font (regular digits with 7 bars would have been so much easier... :-/ ).

Therefor I want to keep the circuits as simple as possible. This is a simplified sketch of what I think it should be like. Each inverter can handle wires between 10-20m, so I choose to use three, makes sense when you're building 3 big characters anyway ;)

Question 1: How can I do this? How do I get the 5v from Arduino to switch 100v cables? I am guessing getting 72 TIP120's or something alike, or is there a better solution? Maybe some way cheaper solution with ICs that can handle these high voltages and do the same? I can imagine there has to be something which has 1 pin for the incoming curent, 8 for the incoming signals and 8 for the outgoing signals. or something alike, does that make sense?) I am not looking forward to solder 72 triacs.. ;) Anyone who has done something like this before?

Question 2: In order to get the required number of outputs I am using planning on using four 74HC595's (+ 1 regular digital pin) to create a three 8 * 3 grids (24 pins where I need 23 on each), which theoretically works fine to control leds, but have no idea if this can handle 72 wires. Should I go for this solution or maybe use a proper (led drivers?) ICs instead? If so, which ones?

I have put myself in a situation which makes me feel completely noobish once more, great!

[u]ANY HELP OR SUGGESTIONS GREATLY APPRECIATED!![/u]

#2

transistors + 74HC595s is how I'd do it.

Note that you can chain 74HC595s to each other, so you can get away with just 2 digital pins for the whole thing.

Of course, the more digital outputs you use, the shorter the chains will be and the faster you'll be able to update the display so it depends on which part of the balance suits your application best.

Oh, remember to connect the -ve side of the inverters to your logic 0v or the transistors won't work properly.

#3

Thanks!

Do you have a suggestion as to which transistor I should use? I don't suppose just any can handle the 100v load, or can they?

remember to connect the -ve side of the inverters to your logic 0v or the transistors won't work properl

Thanks, great tip :)

#4

use a transistor rated for Vce>=150v so you have some headroom. google knows where all the datasheets live

#5

Octopart has a cleaner search which doesn't give all the odorous hits when you search. ;) http://octopart.com/

#6

Okay, so I ordered and received a whole bunch of NPN (Vcb=170,Vce=150,Veb=5) transistors, but didnt pay enough attention: these are mechanically placeable and therefore VERY hard to solder (soooo tiny, and my hands are not). But I'll manage. Here's the datasheet: http://www.farnell.com/datasheets/62375.pdf

Since they are NPN: is this the way I should put them in the circuit?

#7

Add a resistor between the arduino/74hc595 output (which you've labelled +5v for some reason) of about 1k, or you'll blow something up (probably the IC's output rather than the transistor). Remember that a transistor's base-emitter junction looks like a diode to whatever's connected to it.

other than that, it looks fine.

#8