concept - led dimmer board

[scorpia]

Guys,

i have had an idea in my mind for a while which i have decided it might be time to do something about. Mostly the idea is just a bunch of other boards features all rolled into one to make a dimmer board designed specificly to run led's. both single led's and strings of led's.

from where i stand led's have 2 major issue for us.
1. they really like DC.
2. they really like a constant current source.
neither of which are supplied by the current boards.

so my idea is to make a LED specific dimmer board by combineing a led driver chip with a dc adjustable power supply and a pic chip all on one board to allow us to have a software adjustable dc power source and current limited led driver chip to run led's directly off the board.

when i say software adjustable im thinking design a dc switchmode power supply into the board that will run upto a few amps with software adjustable resistors. so the output voltage can be set from the pc.

Also with the led driver chip like a dimmable version of the chip on the grinch. we could also have a software adjustable current limiting resistor so the current can be adjusted for the chip.

Also being led im sure that this could be make to be very energy effiecent so i have the possiblility of it running from a ac source or a dc battery etc as am option with wireless connection (i allways wanted wireless :) ) so that remote nodes could be setup.

now this would probably require a new plugin for vixen or at least an external program to adjust the settings etc.

im assuming also with my thinking that alot of the led strings people want to run require 24v dc or less to run them as well as less than 100ma per string.

i am going to put some more thought into this over the next little while. and see what i come up with. but i guess at this stage its just an idea and im not even sure if i am capable of designing such a board.

So at this stange i guess im looking at peoples idea's / comments etc.

Peter

[RJ]

So would it be something like this but with a built in adjustable switching power supply? I might not be following you but it sounds like basically what you are describing. It uses a dimming version of the grinch chip, and sets the current based on the resistor. I added mosfets for more current but it is setup to be jumpered to run 120ma max current without them. Although without them it is limited to 17 volts.

http://diylightanimation.com/wiki/index.php?title=Manual_MR16

RJ

[aussiephil]

Scorp,

interesting, i like the idea of the software setable resistors.

I have a DMX - DC Power - LED controller laid out in hardware and working on firmware at the moment, steep learning curve but getting there. It will also handle the standard OZ mini strings.
It's required as part of my conversion to full DC power at 48v.

Good luck with your design, i'll be interested in how it goes as we (OZ) need more options for DC controllers.

Cheers
Aussiephil

[scorpia]

RJ,

similar in that it would use the external dimming chip. i am trying to get away with not running mosfets per channel if i can hence thinking of about 100ma per channel.
my thoughts were that the chip basicly didnt care to much about what the +ve rail voltage was as long as the voltage dropped across the chip was within a perticular range. but that was just my thinking so it could be wrong and i havnt checked any data sheets to i havnt considered maximum voltage limits at this stage.

the idea with the software adjustable dc voltage was to allow it to be fine tuned to have low voltage drop across the chip while allowing a big range of different voltage strings to be run.

phil, if you have any more info you wanted to share i would be greatfull. allways happy to look at other idea's