Variable Resistor Controller?

Vorex · 10-07-2005, 01:46 PM

Is this possible? What would be easiest? USB? Serial? Parallel? Only solution I could think of (im no electrical engineer) was motorized pot's and use a serial/usb/parallel controller to adjust them, but that seems like a strange way to do it. Anyone know an easier way? (schematics too preferabily)

mushin · 10-07-2005, 03:10 PM

Search for digital potentiometers. They are digitally controllable variable resistor ICs. Digikey has a wide variety of them for a couple bucks. Interfacing with a PC can be done through any of the usual suspects.

Vorex · 10-07-2005, 04:31 PM

so the easiest way would be using the digital i/o's of phigets? Will they be capable of controlling digital pots?

mushin · 10-07-2005, 05:07 PM

I guess 'easiest' is in the eye of the beholder. Personally, I'd wire it up to the parallel port, but I've experiance doing that so it would be easy for me to do again (besides, phidgets are pricey.) For others, phidgets may be an easier way to go.

kiltjim · 10-07-2005, 08:10 PM

For the digital pots, all you need is 2 digital i/o's for up and down. You could use anything. Pihdgets is one way to go, but mushin is right, you would be better off going with a parellel port.

And of course, did you wanna use your computer for it, or can this be physically done? Two buttons would do the same job, but you wouldn't have control over it through an application.

Speaking of an application, you can use wizardpc's app for the parellel port relay card if I'm not mistaken.

Vorex · 10-07-2005, 09:42 PM

relays can be wired to a digital pot? I thought it needed some special i/o that phidgets have--if so i'll get that relay card monday because that website's storefront is only 20min from here....

kiltjim · 10-07-2005, 09:44 PM

No, I was unclear. You would use the app, and connect the input of the digital i/o to the parellel port directly (or with some filtering/protection). You wouldn't use the relay card. Just the port.

Vorex · 10-07-2005, 10:43 PM

Thing is I have 3 seperate lights I need to control independantly...thats why I figured phidgets would be best--can the parellel port handle all 3? or would I need to use more then one get the the result?

kiltjim · 10-07-2005, 11:16 PM

Parellel port can handle upto 8 outputs.

8/2 = 4

You're good to go.

kiltjim · 10-07-2005, 11:19 PM

You are going to need an app that has timers though. I don't remember if wizrdpc's app had them in the final edition. I know it turned them on, and off, but you need it to turn the pin on momentarily.

And if I ever get the thing I am working on finished, it will be upto 256 outputs. Sweet!

Vorex · 10-07-2005, 11:36 PM

heh, any schematic? I think I could handle the software, what im doing is clusters of RGB led's to change the color of a room (could be applied to a car too but thats sometime off for me) I already have them working with regular pot's...I got the idea from: https://netfiles.uiuc.edu/bkpeters/www/LEDBed/ but i figured if it was controlled by your computer it would be alot cooler, I plan on making a winamp plugin that will change the color of the room to the music...

kiltjim · 10-08-2005, 09:08 AM

http://pdfserv.maxim-ic.com/en/ds/DS1669.pdf

Thats the datasheet that shows you it in action. You would pick the application that would replace the pot.

markland556 · 10-08-2005, 03:02 PM

wow, just checked out that site, that has got to be the coolest lighting thing iv ever seen. Im gunna try this out too. LOL

But it would be pretty awsome to change the colors via computer.

kiltjim · 10-08-2005, 11:46 PM

I wanna say maybe 2 years ago, I was playing around with the X10 home automation software, and that would've made an excellent candidate for this. Set colors, at set times: wakes you up with bright white, then a few minutes later with a nice mellow color, by the time you were getting your coffee it would ne back to white again.

I wish I had enough LEDs for this. It would be pretty cool. For now, I wish I could control the fog lights in my car.

Vorex · 10-15-2005, 05:26 PM

I have x10 controlling my house and to have indivdual modules for each light would be LOUD, lol most of the modules make a really loud pop because they use crappy relays when they are activated, i would hate in the middle of the night POW POW POW POW POW firing through the house, plus with x10 you only have 256 possible unique units which makes for 85 indivdual light fixtures (/3 for RGB lights) and in 1 room alone I am using about 35 RGB fixtures...--plus all the rest of the x10 stuff takes up alot of the space too--and X10 is rather slow to respond...

Anyone have a cheap site for LEDs? I feel like im getting shafted, there was one site i used to use that was pretty cheap but i forget the name, it was "ls something"... the last order I did was like 30 bucks from besthongkong.com or something--lots o' leds but that still seems like alot =/