LED drivers

[vitreous99]

Was close to buying the ChaetoMax for a refugium in the back of my biocube 29 and then realized this was a great learning opportunity... So I'm gonna do my first LED dyi. 

 

4 x 3w LEDs (Forward Voltage is 2.3V@700ma) 

 

I am assuming that I need a driver than can supply 700ma of current or less... at 9.2v (2.3v x 4 leds)... Less if I want to dim? 

 

This driver can't supply low enough voltage? 

"-Max # LEDs -7 LEDs  (or combined LED voltage not exceeding 24.5V)

-Minimum Voltage output - 12.5Vdc" 

 

Is there a min number of LEDs a driver can drive? 

[Lingwendil]

Each driver you find will have minium and maximum voltages. The Meanwell LDD series are the most common and versatile drivers and are very common in these projects, and feature a 3 volt drop from whatever voltage you supply it with, so you need to keep that in mind... The LDD-L will be perfect for most lower-voltage needs. If you need more than 32~36 volts, the LDD-H series is what you want.

 

LDD_L series at LED supply are as cheap as $3.49 each, $4.49 each if you want the wired version. All the specs are listed on the page. Free shipping on them too!

 

I use the L series a bunch, very foolproof and affordable. I like to use 19 volt laptop power supplies with them, and since these drivers are a "switching" power supply, they will not run any hotter at higher voltages this way.

[rO.oster]

13 hours ago, Lingwendil said:

Each driver you find will have minium and maximum voltages. The Meanwell LDD series are the most common and versatile drivers and are very common in these projects, and feature a 3 volt drop from whatever voltage you supply it with, so you need to keep that in mind... The LDD-L will be perfect for most lower-voltage needs. If you need more than 32~36 volts, the LDD-H series is what you want.

 

LDD_L series at LED supply are as cheap as $3.49 each, $4.49 each if you want the wired version. All the specs are listed on the page. Free shipping on them too!

 

I use the L series a bunch, very foolproof and affordable. I like to use 19 volt laptop power supplies with them, and since these drivers are a "switching" power supply, they will not run any hotter at higher voltages this way.

If voltage is minus 3V fro whatever you supply, how many Amps does the power supply have to be?  i.e can you use a 12V 1A wallwart as a powersupply?

[Lingwendil]

You might be able to do it with a 12 volt power supply, and since the string will only use .7A, the 1A supply should be fine. You may encounter issues with headroom for adequate voltage at such a close margin though. Won't know until you try it, but if you haven't bought the power supply yet, go with a higher voltage (14~24 even would be fine, the LDDs won't care about the extra) to give you some breathing room.

[rO.oster]

What about a driver like this:

 

http://disti-assets.s3.amazonaws.com/straightroadelectronics/files/datasheets/7986.pdf

 

It says its for 1-3LEDs, but is that based on an assumption of the forwarding voltage?  What would happen if you tried to run 5 LEDs, total voltage at 350mA is 11.25V, on the CU3512-01 driver?

[Lingwendil]

Correct. Forward voltage is all the driver cares about. It can't "see" how many LEDs are in each string. So long as the string is within the capabilities of the drivers output you should be fine.

 

 

[Cintax]

There are several options here depending on your skill level, familiarity with electronics and available tools. It's important to note that LEDs are best operated as constant current devices so the forward voltage will fluctuate based on the current presently passing through the load. A 700mA driver will provide 700mA at 100% duty cycle. If you have the channel set to 50% duty cycle than the driver should be providing approximately 350mA. My 30 gallon tanks has an LED array using Mean Well drivers controlled by an Arduino. I have run the same array using LDD drivers controlled by an Arduino. I spilt water on it and killed the driver board unfortunately. I am presently working on an array using an ESP8266, Nanobox V3.1 array and the Blynk application on my phone. If you intend to have these come on and off at one brightness, you can do this quiet simply. I would look into a Mean Well driver that does the AC/DC and LED driving on one. For on and off time, you can run it on a simple timer. What are your goals with this DIY project?

[rO.oster]

59 minutes ago, Cintax said:

There are several options here depending on your skill level, familiarity with electronics and available tools. It's important to note that LEDs are best operated as constant current devices so the forward voltage will fluctuate based on the current presently passing through the load. A 700mA driver will provide 700mA at 100% duty cycle. If you have the channel set to 50% duty cycle than the driver should be providing approximately 350mA. My 30 gallon tanks has an LED array using Mean Well drivers controlled by an Arduino. I have run the same array using LDD drivers controlled by an Arduino. I spilt water on it and killed the driver board unfortunately. I am presently working on an array using an ESP8266, Nanobox V3.1 array and the Blynk application on my phone. If you intend to have these come on and off at one brightness, you can do this quiet simply. I would look into a Mean Well driver that does the AC/DC and LED driving on one. For on and off time, you can run it on a simple timer. What are your goals with this DIY project?

Just to simply run a 5ish LED array on thre oustide of Chamber 2 behind a Biocube tank for chaeto growth

 

In my display, with 42w 700mA invertronics, I dim and run these at 40-50% and grow SPS.

 

I think a constant current 350mA 13v supply puck is the ideal situation here, controlled by a timer in reverse cycle to the display lights.  Just need to calculate the total forwarding voltages and be under the max output voltage of the supply.

 

We are trying to find a LED driver weak enough to drive small numbers of leds in a inexpensive simplistic fashion.

[vitreous99]

I'm concerned that 350mA isn't enough and that 700mA is probably overkill for our application. Although I would have preferred an integrated power supply and driver I've ordered an LDD-700L (not H) and I'll find a computer AC/DC power supply as Lingwendel suggests.

 

As for dimming I'll probably use an Arduino Nano... But now I'll have to have 2 sources of power... Which feels less than ideal. 

 

This link is a worth while summary of all of the options meanwell offers... 

 

https://www.ledsupply.com/blog/#article/1634

 

Probably could have found more precise option if I was more patient. 

 

I am still confused about the LDD-700H... Could it safely drive only 1x3W LED w/forward voltage of 2.3 volts?

 

[Cintax]

Based on your indication you plan to have four 3W LEDS you can likely go with something like a 12V 1A power supply. You can get these fairly cheaply or salvage one from something you have around. I would use a DC/DC switching board (super cheap on AliExpress) to get me the 5V needed for the Arduino, but you could use a LM7805 voltage regulator with a heatsink on the cheap. 

 

The output range on an LDD-700L is 2-36Vdc. The sum of the forward voltage from your four LEDs is 9.2Vdc at 700mA according to your specifications. The driver appears to be able to run anywhere between one and fifteen LEDs with a forward voltage of 2.3 Vdc at 700mA provided you have a power supply large enough. 

[vitreous99]

23 hours ago, rO.oster said:

What about a driver like this:

 

http://disti-assets.s3.amazonaws.com/straightroadelectronics/files/datasheets/7986.pdf

 

It says its for 1-3LEDs, but is that based on an assumption of the forwarding voltage?  What would happen if you tried to run 5 LEDs, total voltage at 350mA is 11.25V, on the CU3512-01 driver?

rO.oster, CU3512-01 says 1-3 for 1W(watt?) LEDs. The LEDs I'm looking at are, I believe, 3 watt LEDs (LUXEON Sunplus). Think we'd have to move up to the CU7012-01, and even then you'd be limited to 2 LEDs. 

[vitreous99]

1 hour ago, Cintax said:

Based on your indication you plan to have four 3W LEDS you can likely go with something like a 12V 1A power supply. You can get these fairly cheaply or salvage one from something you have around. I would use a DC/DC switching board (super cheap on AliExpress) to get me the 5V needed for the Arduino, but you could use a LM7805 voltage regulator with a heatsink on the cheap. 

 

Cintax, you're reminding me of an old almost forgotten arduino project I was involved with. 

 

Really nice DC/DC 5v 1A supply for arduino... 

https://www.ezsbc.com/index.php/featured-products-list-home-page/psu3-5.html#.WmqaFHNOk0M

 

It's a drop in for LM7805 and you don't need a heat sink. Then I could pull off of the same DC source as used for the lights.

[rO.oster]

31 minutes ago, vitreous99 said:

rO.oster, CU3512-01 says 1-3 for 1W(watt?) LEDs. The LEDs I'm looking at are, I believe, 3 watt LEDs (LUXEON Sunplus). Think we'd have to move up to the CU3512-01, and even then you'd be limited to 2 LEDs. 

Do you mean CU7012-01?  As far as limited to 2 LEDs as stated in the description, its all up to how many and at what forwarding voltages they are running at:

11 hours ago, Lingwendil said:

Correct. Forward voltage is all the driver cares about. It can't "see" how many LEDs are in each string. So long as the string is within the capabilities of the drivers output you should be fine.

 

 

But I dont understand fully the 1Watt at 350mA and the 3W at 700mA other than thinking the wattage gets higher as you up the amperage right?

2 hours ago, vitreous99 said:

I'm concerned that 350mA isn't enough and that 700mA is probably overkill for our application.

 

This is the greatest unknown here, so if you can drive it with a dimmable 700mA is your safest bet.  I already have the parts on hand (and shoulda reasearched using before frying my LEDs) so ill give the 350mA x 5 Luxeon Rebel ES LED setup a shot.  We should compare growth results later this year!

[Cintax]

Wattage is a function of Voltage times Current.

P = V * I

 

If you have 12 Volt power supply that can provide 1 Amp then it can supply 12 Watts.

 

Your four LEDs operating at 700mA having a total forward voltage of 9.2 Volts would consume ~ 6.44 Watts.

 

[Cintax]

10 minutes ago, vitreous99 said:

Cintax, you're reminding me of an old almost forgotten arduino project I was involved with. 

 

Really nice DC/DC 5v 1A supply for arduino... 

https://www.ezsbc.com/index.php/featured-products-list-home-page/psu3-5.html#.WmqaFHNOk0M

 

It's a drop in for LM7805 and you don't need a heat sink. Then I could pull off of the same DC source as used for the lights.

Those actually work very well and would be far superior to a LM78xx.

[vitreous99]

47 minutes ago, rO.oster said:

Do you mean CU7012-01? .... 

 

We should compare growth results later this year!

Yes CU7012... Corrected above. Thanks 

 

For sure we'll have to compare! 

[vitreous99]

Thanks http://www.stevesleds.com

Packaged up very nicely...see pic

Got a mystery pack of leds to play with too ?

 

@Lingwendil

I ended up getting the ldd-700L with wires from ledsupply, thanks for the tip there. 

 

It will be a bit before I get get to the build but I'll try to post when I start getting it together. 

 

Another little article I found very helpful on the topic of drivers for any one just getting into leds: https://www.ledsupply.com/blog/#article/931

[vitreous99]

How hot will this ldd-700l get driving 4 3w LEDs? Trying to understand if I can mount the near my arduino nano or do I need to mount it on the heat sink with LEDs? 

[Cintax]

10 minutes ago, vitreous99 said:

How hot will this ldd-700l get driving 4 3w LEDs? Trying to understand if I can mount the near my arduino nano or do I need to mount it on the heat sink with LEDs? 

It wont get very hot at all. There is not risk in mounting it near your other components.

[vitreous99]

OK controller hacked together... And it's working so far ?

 

Video testing controller cycling with green LED at 100%/75%/50%/25% 

Thinking I'll probably end up at 75%

 

[Cintax]

Awesome. Nice work! I see you went with a DC switching voltage regulator to power the micro. They are perfect for projects like this. 

 

How are you going to process time of day? I use Wemos boards now but my original array runs on a promini with rtc attached via i2c.