Meanwell LDD driver: for those who want to dim to 0 using Arduino

[O2Surplus]

Did you hide that resistor under the LDD, then? I figured it would have to go on the other side.

Also, do they trim the board to fit your layout or will it arrive 5x10 and I have to saw it?

The resistor is a tiny M1206, so it won't interfere with mounting the LDD.(The LDD has soft potting epoxy on the bottom) + if you mount the LDD to an "open frame" chip carrier that will also create extra room for the resistor.

The PCB's will come pre-cut to the dimensions that they were designed with. There's no further cutting necessary.

 

[nemosworld]

I think you guys are doing an excellent job with these board designs, with that said, I was wondering if anyone considered a board with pull down resistors or something else so that we can run fans off the same power supply, i was thinking a 10x10 board with 4 drivers on one side and the step downs and connectors on the other side. hope i explained that right.

 

[O2Surplus]

I think you guys are doing an excellent job with these board designs, with that said, I was wondering if anyone considered a board with pull down resistors or something else so that we can run fans off the same power supply, i was thinking a 10x10 board with 4 drivers on one side and the step downs and connectors on the other side. hope i explained that right.

I try to integrate 12V regulators into most of my driver PCB's as it only costs about $.80 to do so. The problem is- The LDD-H can handle voltages much higher than most 12V regulators can manage. It's easier, cheaper, and more reliable to add a separate DC/DC step down converter to your led build than to try and integrate it all into one PCB design.
Believe me- I've attempted what your proposing and when something goes wrong- It gets ugly.
Here's an example- I crammed 6 CAT4101's, a 12V reg, a 5V reg, and a full blown Arduino w/ ds1307 RTC into one Pcb. It all worked great until one misplaced connection was made and "POOF! $70 went up in smoke!

 

[tomservo]

So here's my PCB design for 10 x LDD arranged in 5 channels (x 2 LDD per). The traces and all are designed for up to 1A per LDD if the board is 1oz copper (typical).

This board is UNTESTED.. I am putting it up for review and to share. I suggest waiting until O2Surplus has at least looked over it before you send any off for production.

This board has a 42v (max) -> 12V switching regulator, and a linear fan speed control with trimpot. All outputs to a 12 pin val-u-lok connector and inputs are through the usual 2-pin terminal strips that O2 used on his. The switching regulator is available in a high voltage version good to 60v if one was looking to do a higher voltage version (up to 52v or whatever the LDD is good for). Digikey even has some of the HV ones in stock but they're about twice the price @ $3.22 ea.

The switching regulator is rated to 1A, which should be more than sufficient as the intention is to pair 1 board with 1 light (and presumably 1 fan).

I'll copy a parts list for this later, as well.

 

[iced98lx]

would be good to pass a PWM to the fan for speed control vs the trimpot, if you wanted. You could then ramp up the fan based on light % values or other programmatic values. Just a suggestion

 

[O2Surplus]

OK- I'm looking it over now.

 

[O2Surplus]

Tomservo-

I looked it over and made a few tweaks. I added a ground plane to the top & bottom layers( using the "Polygon" command) and eliminated all the extra ground traces. I also re-sized and relocated a few traces. It passes the Itead DRC as is, but spend some more time with it and tweak it to your liking.

 

[Eud]

O2Surplus,

I'm playing with modifying your board a bit to use 3.5mm connectors instead of 3.81mm just because they're only 20 cents from iteadstudio instead of close to $1 from Mouser for the phoenix ones.

80 cents each doesn't seem like that big of a deal, but it ends up being quite a few dollars if I bought enough of them to distribute to folks when I mail out the extra boards I'll get from iteadstudio. Or is there another place you like to go to for components? Mouser also sells those 1206 resistors for like $1.50 each which seems kind of high too, but I'd been planning to just order all of the bits from them because they're the only in-stock source for the LDD drivers at the moment, even though they're expensive.

Do you think it's a bad idea to use the 3.5mm ones?

 

[O2Surplus]

O2Surplus,

I'm playing with modifying your board a bit to use 3.5mm connectors instead of 3.81mm just because they're only 20 cents from iteadstudio instead of close to $1 from Mouser for the phoenix ones.

80 cents each doesn't seem like that big of a deal, but it ends up being quite a few dollars if I bought enough of them to distribute to folks when I mail out the extra boards I'll get from iteadstudio. Or is there another place you like to go to for components? Mouser also sells those 1206 resistors for like $1.50 each which seems kind of high too, but I'd been planning to just order all of the bits from them because they're the only in-stock source for the LDD drivers at the moment, even though they're expensive.

Do you think it's a bad idea to use the 3.5mm ones?

I used the 3.81mm screw headers on that board because I'd scored 400 of them on FleaBay last year. IIRC, I paid less than $.05 each. I source most of my parts through DigiKey, but I also use http://www.findchips.com/avail?part= just to make sure that I'm not getting hosed. Do a search for yourself, and I'm sure you can locate cheaper sources, paying $1.50 for a 1206 resistor is akin to highway robbery.

 

[Eud]

OK. I'll look around. I'll also ask the guys at work who know about such things.

 

[Neoferdina]

Thanks MagicJ for that info. Super helpful. I'll try to machine up my enclosure this weekend and see how things go in the enclosed space.

I think you guys are doing an excellent job with these board designs, with that said, I was wondering if anyone considered a board with pull down resistors or something else so that we can run fans off the same power supply, i was thinking a 10x10 board with 4 drivers on one side and the step downs and connectors on the other side. hope i explained that right.

As mentioned previously, I'd do a separate DC/DC step down off the main board. They're cheap off eBay. From experience they have a tendency to go whacky on you, especially if you're not paying attention.

What I'm doing (and this might be a good mod for the future boards as well) is to put the DC/DC step down off the driver board (I'll be putting mine right in the hood) and control the input power to it using a PN2222 transistor on the driver board. What I'm doing here is using channel 1 (I'm calling the first channel that turns on in the morning and last to turn off at night channel 1 - ie. royal blues) to control power to the fans. If you connect the base of the of the transistor to the Vout,+ of the driver through a high value resistor (5K to 10K) and connect the collector to the -ve pin of the DC/DC step down and the emitter to ground, the transistor acts like a switch (since it will be in saturation).

To translate this into English, when the driver is dimmed to "off"/0% there is no voltage applied to the Vout,+ pin - thus the fans are off. But as soon as the driver is dimmed on, even the slightest bit, the transistor "switches on" and turns on power to the fans. This way the fans only come on when the LEDs are on and you don't need to waste a channel on your controller and extra time programming in order to control your fans. The PN2222 transistors are about $0.15 ea... much cheaper than all the fancy fan controllers people use.

 

[tomservo]

Sorry, whacky double post..

 

[tomservo]

You really ought to look somewhere other than mouser, they are famous for having terrible pricing to individuals / small orders.. They're like auto parts stores. Try Digikey, or ebay for some of that stuff. Digikey is in minnesota and they ship out very quickly and for low money. (Those $1.50 resistors are $.18 at digikey)

O2: Thanks, I couldn't really figure out how to do a ground plane, so this is obviously much better. It's good to have someone else look these over, and with the different layout I noticed I hadn't made the shared channel 4 & 5 out- trace as big as it ought to be - fixed, now. Also, after reviewing 2 pin terminal block pricing, I changed the board to use an 8 terminal block from digikey at only a slightly higher price but I can have it tomorrow instead of in 2-10 weeks from china. Do I need to do anything to connect the ground plane to the ground terminals?

iced98: The fan speed is controlled by temperature, I think this is a better solution than controlling it by an arbitrary PWM value, but it would be easy enough to change.

 

[Eud]

Well, looks like I can get 100 of those 1206 resistors for $4, 100 of the 3.81mm headers for $16, and 20 of the machined pin socket adapters for $8 all shipped from China in 2 weeks, heh. not bad. Glad you suggested to look there instead of where I was looking.

 

[Eud]

Neoferdina, darn you, that sounds like a good idea too, but I think I'm going to pull the trigger on this design instead of waiting for O2Surplus to make another mod to a board to add what you're suggesting.

 

[Eud]

OK. I ordered parts and the RGB boards that O2Surplus just posted. Will post back when they arrive with pics. 8)

 

[zachts]

octoparts is a great search engine also for comparing part cost and availabity. I recently saved $5 bucks on an order for one part even after shipping over digikey by ordering from arrow electronics for one part out of my order. It pays to shop around.

Ocotoparts will tell you everyone selling LDDs and who acualy has the ones you want in stock!

 

[Neoferdina]

Neoferdina, darn you, that sounds like a good idea too, but I think I'm going to pull the trigger on this design instead of waiting for O2Surplus to make another mod to a board to add what you're suggesting.

:frog: You can still implement it. You can just free-form solder the resistor and transistor in place. They don't necessarily need to be on the board.

 

[Eud]

:frog: You can still implement it. You can just free-form solder the resistor and transistor in place. They don't necessarily need to be on the board.

Ok. I will give that a try. I think I'm also going to take the outputs and run them through a double row of terminal blocks to let me put a big, 5W 1 ohm resistor on each string so I can easily measure current in each string in situ.

 

[rott]

this is off topic would anyone have a few spare regulator 7810 they would part with?