LED Lights,

[MrMoocow]

Hello,
This could be posted in several forums but I guess I'll just choose this one. I need some resources that explain how to connect about 12 LED Digits [0-9], wire em up and such, then connect them to a serial port where a VB program can set the values. I realize this is a pretty big undertaking and don't think someone is going to give me a walkthrough, but links to any sites even just on the mechanical part would be most appreciated. Brad,
Hey! email me any time! Bradsvb@yahoo.com

 

[johnwm]

This is quite a wide subject.
Try breaking it down into easy bits.
For the hardware bits start somewhere like:

http://links.epanorama.net/links/pc/interface.html

or do a Google search on 'Hardware Interfaces' etc.
As far as the software bit is concerned, you can only do the detailed bit when you know what the hardware will look like, but driving 7-segment LED arrays is quite easy.
Your hardware will finish up with an addressable register for each LED array. It will all be fed from a Serial to Parallel convertor. The output of the various bits will feed each segment, so your sofware will just need to decode a single digit into a bit pattern to light the appropriate segments.

It will all be a lot clearer when you have the hardware under control, si I would start from there! Let me know if this helps
________________________________________________________________
If you want to get the best response to a question, please check out FAQ222-2244 first

'There are 10 kinds of people in the world: those who understand binary, and those who don't.'

 

[THOMASNG]

I'm a specialist at this.
1) Know how LEDS work:
a) A LED is a 0.6 VDC load. Too keep it from
burning out at higher voltages, you need to
place it in series with a resistor (to take
up any excess voltage). Failure to do this
will result in a burnt-out LED!
b) LED's, like all other diodes, are polarized.
Hook them up one way, and the LED comes on.
Hook them up the reverse way, and the LED
stays dark.
Verify these things before proceeding.
2) VB can access the serial ports via MSComm.
3) The data passed by through the serial port will be
in serial format. You will have to add hardware to
interept the signal into something that will light
the correct LED's.

This is probably way beyond your knowledge level! Can
you use a second PC, with the standard (and free)
communications program, HYPERTERMINAL?

 

[MrMoocow]

" Can
you use a second PC, with the standard (and free)
communications program, HYPERTERMINAL?"

Yes I could, as to the first reply i should get the hardware set up first, I figured that. Any suggestions on books or articales though? I hate to waste LED's at 1.99 a pop. Brad,
Hey! email me any time! Bradsvb@yahoo.com

 

[instar4per]

Brad, just wondering, what is your budget on this project?

I can help you with any part of this that you could need (<pimp>I've done electronics, and was on BattleBots </pimp> ).

If you'd like my help, I can, I'd just like to warn you that a cheap solution is going to put you without a parallel port. If you can handle this (go buy a $4 computer from a thrift store, and jack the parallel port from that thing if you need to), then you'll have no problem.

The voltages from the LED's won't be a problem. Just use the +5v from the PSU, and make sure each LED has it's own resistor (you can use a bridge). The reason to not use one resistor for all of them is that causes the LED's to change brightness levels when different numbers of them are on.

A good value to use for +5v is a 1k ohm resistor. This will push 5ma through each LED, which is a nice brightness (but ensure your LED's can handle that much).

Please ask me if you need more assistance, rather than experimenting on your own. I've made some big mistakes getting in over my head...
-iNSTA
aim: instar4per
email: instar4per @ hotmail.com

 

[MrMoocow]

I work at a computer store with lots of 486's and what not lying around, the only rare commedity is LED's, those i have to be careful with. My budget for the initial &quot;look its possible&quot; is something under 30 bucks. Then I'll make the actual project with a bigger budget. You say take the parrel port? Interesting...

Please post more details, and how hard is it to wire? Brad,
Hey! email me any time! Bradsvb@yahoo.com

 

[instar4per]

Yes, parallel port.

This stems from my projects &quot;back in the day&quot;, where I used a hacked joystick to provide digital and analog inputs (I could measure the temperatures of things using a thermisistor), and I could check for open doors with the modified buttons.

I would then use the parallel port and a demultiplexer (A device that essentially converts base 2 into the decimal equivalent) to control up to 128 different devices that required a digital state (on or off), through one 8-bit parallel port.

This was all done through QBasic, mind you. Visual Basic might be more difficult, based on the low-level inputs required.

At one time, I even had serial communications going across my parallel port . It was just rather slow, as it was time-sliced across 127 other channels.

The wiring isn't too difficult, although you need to be careful with it. The first thing I'd suggest doing is going up to your local RadioShack, and picking up:

-an experimenters breadboard
-the 3-pack of 22ga solid-core wires
-the pack of pre-cut breadboarding jumpers
-a value-pack of 1/8w resistors
-at least 8 2N2222 signal transistors

With these supplies, I can teach you to control 8 LED's at the same time. If you need more (and most likely will, if you're running LED displays), then we get into the fun of demultiplexers, capicators, and charge-pumps . -iNSTA
aim: instar4per
email: instar4per @ hotmail.com

 

[phonesex]

Is there something special about your LEDS? Last time I looked you can find some under 2 cents each, and resistors are about the same price.

 

[strongm]

I suspect that MrMoocow is referring to 7 segment displays, rather than simple LEDs...

 

[THOMASNG]

Simple &quot;dot' LED's at $1.99 a pop is WAY, WAY too much!
Mail order them from

http://www.jameco.com.

You can also buy a
pair of &quot;dual-in-line&quot; 330-ohm resistor networks, each
of which will give you eight 330-ohm resistors in a single DIP.
A more sophisicated circuit would use a 7-segment display
and a 7447 decoder driver, but it's too easy for a beginner
to mess it up.

A good place to start would be THE ART OF ELECTRONICS, by Paul Horowitz and Winfield Hill.
A good reference for the nitty-gritty details of the serial port (ie, the actual pin-outs) is BUILD YOUR
OWN LOW-COST DATA ACQUISTION AND DISPLAY DEVICES, by Jeffrey Johnson.
Both of these should be available through your
local library and

http://www.amazon.com.

Thomas Ng

 

[MrMoocow]

Yes as i said before they are &quot;LED Digits [0-9]&quot; (thats what Radio shack calls em). For clarification they are the letter 8, but you only light certain parts ect ect ect. I'm going to go buy supplies hopefully this monday, as I have that day off. Brad,
Hey! email me any time! Bradsvb@yahoo.com