LED and driver questions

[perkint]

I would recommend the LDDs again, for the same reason as suggested earlier. Personally I wouldn't run the XPE2s at 1.5A since they have a max drive of 1A! To be honest, I wouldn't use XPE2s except for deep blue. XTE are better for royal blue if you want Cree and still cheap, and XPG2 or XPG3 (if you can find the 3s cheap) are still good value/performance and much better than XPE2s for whites.

I'd actually do a mix of deep blue, royal blue and white, and run them on a few of the tiny LDD700-L, from a single 12V PSU which can also power the arduino and fans

Tim

 

[liquidis54]

Thanks for the help! 2 more quick questions now though. So you say I shouldn't run the led's past 1 amp. Does that meant that each LED in a string is pulling the same current? I assumed that if I bought say a 1.5amp driver and ran 2 LED's they would each pull 750mah. Is that wrong? And 2, if I use pot's to control the dimmers, how can I still program sunrise/sunset and will the dimmer be controllable from the arduino or will I have to use the pot's?

 

[oreo57]

Voltage adds in series.. Amps add in parallel..
So a series string runs at whatever amps you feed it but need V(f) X diodes of voltage..
10 3V (at say 700mA, current draw and voltage are related) diodes in series is 30V. Note LDD "drop" about 3 V so you would need a 33V (min) power supply.
LDD will control the voltage so the string only gets 700mA, and yes each diode will be at 700mA (approx)

I assumed that if I bought say a 1.5amp driver and ran 2 LED's they would each pull 750mah.

That would be correct IF wired in parallel (not recommended, has "issues"). Not correct if wired in series..

not sure what you would net pots for if you are controlling the PWM w/ the Aduino.. just cut max..

Parallel top,series bottom, in case..

TOP: voltage needs: =V(f) of a single diode.
Amps = 1/3 mA of driver output per diode

Bottom:
Voltage needs 3x V(f)
Amps = mA of driver output

 

[perkint]

I wouldn't use pot's personally. Just use an arduino. For less than $20 you can put a little controller together which will do sunrise/sunset quite easily

Tim

 

[oreo57]

I wouldn't use pot's personally. Just use an arduino. For less than $20 you can put a little controller together which will do sunrise/sunset quite easily

Tim

Or this for $25-ish..Need to shop arounfd though..

 

[perkint]

Yeah, I know you like that one, but I prefer the full DIY solution. Nothing to do with having written my own controller code or anything like that :thumbsup:

Tim

 

[oreo57]

Yeah, I know you like that one, but I prefer the full DIY solution. Nothing to do with having written my own controller code or anything like that :thumbsup:

Tim

Well the only reason I like that one is avoids reinventing the wheel for many..
and, sometimes, 1/2 the price of anything else available..and close to the full DIY w/ only a little solder sweat equity.
Still..got to put up w/ the goofy Chinese software and need a computer to program it..

Coding is for masochists..:lolspin:

 

[liquidis54]

The arduino nano v3 is essentially the same as the Uno for functionality. It has 6 PWM channels (0-255 levels) so you can easily bolt 6 pot's onto a nano and output a PWM signal based on each pot' reading to each of the 6 channels. The PWM signal goes straight to the LDD (although a pull down resistor can help prevent the LEDs flashing on at full power when rebooting).

This is what left me confused about using pot's with an Arduino. I had just assumed that the Mean Well Drivers used an analog dimmer so you had to use a pot to simulate an analog output. Also, you guys are super helpful. I really appreciate it!

 

[perkint]

Well the only reason I like that one is avoids reinventing the wheel for many..
and, sometimes, 1/2 the price of anything else available..and close to the full DIY w/ only a little solder sweat equity.
Still..got to put up w/ the goofy Chinese software and need a computer to program it..

Coding is for masochists..:lolspin:

True - I code for a living and enjoy messing around with stuff for myself at home, but finding the time is not easy!

This is what left me confused about using pot's with an Arduino. I had just assumed that the Mean Well Drivers used an analog dimmer so you had to use a pot to simulate an analog output. Also, you guys are super helpful. I really appreciate it!

You can use the pot's as a simple solution if you just want to be able to manually alter levels and do not want to mess around with a screen and user interface. The LDDs only take PWM dimming, not analogue.

Tim

 

[consumer]

Hmmm I thought I saw an LDD driver at some point that could actually do dimming via an internal pots. But yeah might as well use an arduino for that and shell out the extra few $$$

I have another question, I probably should start a new thread for, not sure. Anyway I'm sourcing all the materials I need to build my super light, and one of the final pieces of the puzzle are optics.

What degree of optics should I have? For example, my tank is 24" wide, 24" tall, if I run two rows of lights at about 8-10" above water level (at the most), I'm thinking I would probably be best to have 40 degree optics? That should pin-point the light nicely but also have all the tank covered. Or should I 60 degrees? I think because I'm running two rows that the 40s should be ok.

I have decided to go with the XP-G3s for the white lights then throw in some red/deep red and cyan, and obviously royal blues as well. The XP-G3s can run at 2A, so I'll get the LDDs that have a 1.5A current which should fit nicely. The XP-G3s that I am sourcing have the highest bin but a minimum CRI of 70, but I think that should be ok because I am having reds as well. All colours dimmable by separate LDDs.

Having ~50 or so of those LEDs is surely going to be enough light.

What a learning experience!

 

[oreo57]

40 degree optics give 6" cones of light at 8" at the water line.
Blending colors also becomes problematic..

@60 your cones are 9"..
by 30" light to substrate your cone has widened to 34.6"

 

[consumer]

Ok I probably should get 60 degree ones then.

Can I just get any brand optic? Are they all fairly similar?

 

[perkint]

Never used optics myself, but my understanding is that they are anything but all the same!

Tim

 

[oreo57]

Ok I probably should get 60 degree ones then.

Can I just get any brand optic? Are they all fairly similar?

Optics are not my forte..but I lean towards reflectors over lenses at angles around 60-90 degrees..
But here are a bunch of choices:
http://www.carclo-optics.com/optics-for-leds/cree/xp-g3/?bp[offset]=0&bp[limit]=300

80 degree reflector:
http://www.digikey.ca/product-detail/en/carclo-technical-plastics/10170/1066-1010-ND/2641626

Ledil is another popular brand..

 

[perkint]

Not seen them before - look interesting

Tim