I'm only about 75% sure that that's right. I'm hazy on the subject myself, but that seems correct, yes. O2Surplus or some of the more experts here should confirm.
Meanwell LDD driver: for those who want to dim to 0 using Arduino
- Thread starter pwreef
- Start date
I'm only about 75% sure that that's right. I'm hazy on the subject myself, but that seems correct, yes. O2Surplus or some of the more experts here should confirm.
rrasco
Active member
I think the ones people were using were SMD? If not, 1/4W may be too much resistance and affect the dimming signal.
Oops, I did exactly this... electronics noob + lots of wires + guessing = massive fail.
Somehow I had the brilliant idea of connecting the arduino ground to the (-) wire output (v out) on the driver. I touched it very briefly, it made a sound so I immediately broke the connection. Then over about 2-3 seconds the LEDs flickered a bunch and the driver EXPLODED! Seriously it blew a bunch of resin out the side and started shooting out smoke like a firecracker. It smells horrible. The LEDs aren't burned out at least, but now I need a new driver.
Could someone be a hero to all us noobs and draw out a simple diagram on how to dim these using a pwm signal from the arduino? Seriously that would rock. I need to figure this out so I can order another driver and not worry about screwing up another driver.
rrasco
Active member
Hahaha....good story.
Don't feel bad, I blew a whole bank of drivers on a system. I had everything wired up and my little snafu was when I was testing, I connected the PWM signal to a 12V source instead of the 5V terminal right next to it. Nothing exploded, but they certainly don't work anymore. Live and learn.
Don't feel bad, I blew a whole bank of drivers on a system. I had everything wired up and my little snafu was when I was testing, I connected the PWM signal to a 12V source instead of the 5V terminal right next to it. Nothing exploded, but they certainly don't work anymore. Live and learn.
Nothing special about the tiny ones except that they fit nicely under the LDD. As long as they're 10k resistors or higher seems like you could put whatever size you were comfortable with. It's a pull-down resistor, just intended to be a high enough resistance that in normal operation no current flows from the PWM pin but when the voltage is turned off the pwm pin is shorted to ground. you won't run hardly any current through it ever, so no need for a 1/4 watt one.
Disaster averted!
1) Due to living very close to a certain well-known figure in the aquarium LED world I was able to pick up another meanwell LDD-1000h - I've lost track of how many times he's helped me out. This one has pins out the back instead of wires, but I found a $.99 IC socket at radio shack that fits this thing perfectly!
2) I figured out the PWM dimming and successfully tested it out on one of my LED strings. I decided to go over this thread once more in-case I missed something and indeed there was a good schematic on post #523 on page 21.
Turns out it's really simple and I almost stumbled on it on my own.
1) Due to living very close to a certain well-known figure in the aquarium LED world I was able to pick up another meanwell LDD-1000h - I've lost track of how many times he's helped me out. This one has pins out the back instead of wires, but I found a $.99 IC socket at radio shack that fits this thing perfectly!
2) I figured out the PWM dimming and successfully tested it out on one of my LED strings. I decided to go over this thread once more in-case I missed something and indeed there was a good schematic on post #523 on page 21.
Turns out it's really simple and I almost stumbled on it on my own.
So I'm still struggling a bit with the right way to get 12V and 5V out. I don't have the education to build my own circuit around a switching regulator, and a linear one, if I understand them right, is basically a fat resistor, which seems like it wouldn't be the best thing.
I feel like the problem some people are having with dimming using something like the Steve's Aquarium Controller Interface is caused by using an inconsistent common for the 5V input to his board and the reference common that the LDD measures the PWM signal against, which must be the V_in- of the LDD coming from the 48V power supply. I bet people buy a 5v wall wart and use that to power the Steves controller and to generate the PWM signal, and it doesn't work.
At the moment I'm thinking I'll buy one of these:
http://www.mpja.com/48V-Input33V-5V-and-Dual-12V-DC-to-DC-Converter/productinfo/18248 PS/
Which will give me 5v and 12v outputs and should have the same common as the power supply and the LDD input.
You folks who know things, does this seem right?
Alan
sfsuphysics
Active member
Kind of splitting hairs, but aren't the LEDs backwards in that diagram? Vout+ goes to the anode side of the LED (the bottom part of the triangle symbol). I realize that the LEDs often have + and - written on the boards they're mounted to, but it was one of those little things I learned from electronics class so might as well put my knowledge to use
Or actually it looks like these could be used to power an aquarium controller interface?
Meanwell SCW05C-05
http://www.jameco.com/Jameco/Products/ProdDS/1953330.pdf
Fan could easily go on a wall wart since nothing cares about the common for that.
Edit: Nevermind. Those look like they're made of unobtanium. Saw one on ebay from taiwan, but that's it.
Meanwell SCW05C-05
http://www.jameco.com/Jameco/Products/ProdDS/1953330.pdf
Fan could easily go on a wall wart since nothing cares about the common for that.
Edit: Nevermind. Those look like they're made of unobtanium. Saw one on ebay from taiwan, but that's it.
sfsuphysics
Active member
Yeah if you order some do yourself a favor and order some extras just in case. Even if you're confident you won't blow one up like I did you could potentially end up a hero to someone else who did
Apex 0-10V VDM to one of the Steve's Aquarium Controller PWM interfaces shown here:
http://shop.stevesleds.com/product.sc?productId=47&categoryId=29
which takes a 0-10V analog signal and outputs a PWM signal for digital dimming drivers like the Steve's drivers. Then that PWM signal gets sent to the PWM input of the LDD. You have to supply the interface with 5v, though, which I think should probably share a common with the Vin of the LDD.
Steve says that you can power his interface from the 5v output he provides on his drivers, but since I'm using the LDD, and not his drivers I gotta get 5v from somewhere else.
I got the boards! 10 of the O2Surplus 3-up boards including the pull-down resistors, which I'm still not confident I'll be able to solder without shorting them out they're so tiny.
Ordered Jan 22, so just about 4 weeks with the slowest shipping.
I also got an Arduino Uno board and a XBee Pro for free.
Ordered Jan 22, so just about 4 weeks with the slowest shipping.
I also got an Arduino Uno board and a XBee Pro for free.
Soldering the resistors is easier than you think. I should tell you that I did find one small defect with that Pcb. The pulldown resistor in the very middle is not connected to ground. You'll need to scratch the coating next to the ground pad and connect it with a small bit of solder. Other than that the Pcb works perfectly.
Ok, thanks. Will scratch it off and solder it. Going to try to build the boards tomorrow.
