April's Arduino LED Controller - The Planted Tank Forum
 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 02-21-2012, 06:28 AM Thread Starter
Planted Tank Obsessed
 
Gnomecatcher's Avatar
 
PTrader: (4/100%)
Join Date: Sep 2011
Location: SLO, CA
Posts: 471
April's Arduino LED Controller

So I'm building an LED array with an Arduino microcontroller to simulate a sunrise/sunset effect. I will eventually add on more things, such as an auto-top off, auto-fertilizer (?), auto-water changer, temp and PH monitor, and maybe an ethernet shield with a camera so that I can get email updates with pictures of the tank. I know it's all a little over the top and unnecessary, but I think it'll be a cool way to learn electronics.

Today I got a lot done while I was putting off studying for my econ midterm tomorrow (this is what is wrong with America: priorities). Please excuse any non-tech terms that I use, or if I refer to something incorrectly or think crazy thoughts, as I am a total newbie to electronics (this is my first project ever) and I have had no education whatsoever in this area save what I have learned this quarter in my E&M physics course. If you could do me a favor and correct me whenever and wherever appropriate, I will be very grateful for it.

Anyways here's a quick explanation of what I've got. I don't have much time cause I've got to get some sleep soon. I have 12 Cree XP-G cool white LEDs, a Meanwell 60-48 P dimmable driver, and an Arduino Uno that I'll use with a blank protoboard and a DS1307 real time clock. I have hooked up everything onto a breadboard for now, and I'm using a 2n2222 NPN transistor with a 10V power supply for my PWM input from my Arduino. When I measured the voltage from the power supply (I guess it's a wall wart...?) it was 13V when hooked up to my transistor circuit, so I used a adjustable voltage regulator to get it down to 10V because Meanwell doesn't specify a range for the PWM input. It just says 10 volts, but I don't know how close I have to be to 10V, so I played it safe. The transistor pulls the 10V to ground as the Arduino turns it on and off, and I can vary the duty cycle from the Arduino with one of the example codes it came with until I write my own code. For now I am trying to get the hardware finished before I start learning to code, so that I can have something to test the code on.

So the problem I ran into today was that when I finally finished and had everything hooked up, I found that it was incredibly difficult to adjust the brightness of the LEDs smoothly. I am adjusting their brightness by adjusting the duty cycle from my Arduino, but the brightness of the LEDs rapidly decrease between somewhere around 13-14% (duty cycle), and the current jumps from 230 mA to 0 really fast. I want to be able to somehow limit the current further and push back the threshold voltage so I will have more room to work with. I added a resist in parallel and it had the desired effect, but I feel that this is tacky and a waste of power. All I had was a 5W resistor laying around, and it got hot in less than a minute, so I would need a 10W if I did use this method.

Does anyone have any ideas on how I can improve on all this? I suppose this isn't the most appropriate place to get advice, seeing as I would find more advice on an electronics or Arduino forum, but I thought I'd ask anyways.

Maybe tomorrow I will draw up a circuit schematic if that will help anyone help me.

EDIT: Just a note that I'm not sure is helpful or not, but when I applied my 10V PWM signal to my driver, it was reduced to approximately 7V.

EDIT EDIT: If anyone has suggestions for what else I could add on to my controller, have at it!

I moss be in love

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by Gnomecatcher; 02-21-2012 at 03:52 PM.
Gnomecatcher is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 02-21-2012, 12:54 PM
Algae Grower
 
PTrader: (5/100%)
Join Date: Aug 2008
Location: Lakeland, FL
Posts: 138
I've found a few threads on different reef forums for this project. I'll find them again and post them here during lunch.

Subscribing as I've been looking to build a controller too.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pb300 is offline  
post #3 of 6 (permalink) Old 02-21-2012, 04:21 PM
Planted Tank Enthusiast
 
O2surplus's Avatar
 
PTrader: (4/100%)
Join Date: Jan 2010
Location: "Out West, in the Land of Fruits & Nuts"
Posts: 877
Your dimming trouble is a well documented behavioral trait of the Mean well led driver.There are plenty of threads around that describe the exact same problem. The driver will not exhibit linear dimming below about 15%. If you want extreme linear dimming performance you'll have to either find an "off the shelf" driver that meets your requirements, or build your own driver using the Onsemi CAT 4101 or National Semi Conductor LM3409. Both of these Chips can be dimmed to less than one tenth of 1%.
O2surplus is offline  
 
post #4 of 6 (permalink) Old 02-21-2012, 05:08 PM
Algae Grower
 
PTrader: (5/100%)
Join Date: Aug 2008
Location: Lakeland, FL
Posts: 138
Here is one of the threads. They even get an android app working with the controller.
http://www.reefcentral.com/forums/sh....php?t=1987110


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pb300 is offline  
post #5 of 6 (permalink) Old 02-23-2012, 04:17 PM Thread Starter
Planted Tank Obsessed
 
Gnomecatcher's Avatar
 
PTrader: (4/100%)
Join Date: Sep 2011
Location: SLO, CA
Posts: 471
I saw that thread, but it's soooo long. I couldn't even make it to the end.

I didn't even realize that they made an android app for it.

I moss be in love

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Gnomecatcher is offline  
post #6 of 6 (permalink) Old 02-23-2012, 05:45 PM
Algae Grower
 
PTrader: (0/0%)
Join Date: Nov 2011
Location: Winnipeg, Canada
Posts: 107
I'm assuming your resistor is in parallel with the LED array?

Another option could be to run two strings of emitters in parallel, although that wouldn't work if you wanted more than ~650ma current.
tentacles is offline  
Reply

Tags
None

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome