on/off timer for diy led build?

sk8ter20art

New member
i am in the process of building my first LED light for my 20g. trying to keep things cheap and simple. I already have my leds, drivers.

trying to figure out a diy method to making my own on/off controller for my lights, nothing fancy just day/night mode. I work a rotating shift so sometimes i get home very late to change the light mode on a decent schedule. The light i am using is a cheap light meant for freshwater and is not bright enough, and has no timer.

I do have an arduino duemelove, just not familiar with using RTC for this type of purpose. would like to have ability to change the on/off times if necessary. I am capable of soldering circuits together just not knowledgeable enough to create them.

google search didn't provide any results that i saw suitable for this project, or had too much going on to simplify what i needed. So if anybody can point me in the right direction that would help a lot.
 

dread240

New member
easiest way imho is with a driver capable of fully turning off with the dimming circuit

since you already have an arduino, pick up some meanwell ldd drivers and a laptop power supply (more then enough power for a small 20g build)

run the dc power from the laptop power supply to the ldd's... and buy a simple rtc board (I picked one up off ebay for like 3 bucks shipped prebuilt)... use the prebuilt sketches to make it work, and build your timers off of that
 

Ronic

New member
+1 with what Dread240 said.
If you go with the laptop power supply it could feed the power to the arduino and the led's so you will just have one power cord. And it can all be stuck into a project box to make it nice and clean.
 

mcgyvr

New member
Well you didn't give any info on the drivers so its impossible to really answer without those details BUT..

Just get 2 regular lamp timers. One for day, one for night.
 

dread240

New member
regardless of driver model, i still don't see where people have made a on/off timer for there setup. do all the diy people just manually change it over?

I have been looking at the using the arduino with pwm for dimming and using a transistor to switch between the external power supply. based off this tutorial

http://thecustomgeek.com/2011/08/30/using-pwm-outputs-with-an-arduino-and-a-led/

my on/off timer is the arduino... I control 6 channels of LED"s all driven off of meanwell ldd-700h (12 drivers total), the arduino varies the pwm output to the dimmer throughout the whole day... ramp up for a few hours, stay at peak, then ramp back down to off (well i leave a few violet and blue on for moonlights, but 95% are off)

You also don't want to be driving the high power 3w led's directly from the arduino. That's why we're all using seperate drivers and using either pwm or analog signals to the drivers to control dimming
 

sk8ter20art

New member
Looks like I am going to be using transistors and pwm from the arduino to drive the leds. And a old external hard drive dc converter 12v 2A for power. Dread240 you mind sharing your arduino sketch?

Probably gonna include 3 2in pc fans to aid in cooling. And get a dedicated arduino micro.
 

moncapitane

New member
on/off timer for diy led build?

Looks like I am going to be using transistors and pwm from the arduino to drive the leds. And a old external hard drive dc converter 12v 2A for power. Dread240 you mind sharing your arduino sketch?

Probably gonna include 3 2in pc fans to aid in cooling. And get a dedicated arduino micro.

You might check out the other posts for arduino on this forum. There are tons of good programs out there, some even include sunrise/sunset and storms. Here are just a few of those:
http://www.reefcentral.com/forums/showthread.php?t=2210357
http://www.reefcentral.com/forums/showthread.php?t=1987110
http://www.reefcentral.com/forums/showthread.php?t=1847680
http://www.reefcentral.com/forums/showthread.php?t=1831741
 

mcgyvr

New member
Looks like I am going to be using transistors and pwm from the arduino to drive the leds. And a old external hard drive dc converter 12v 2A for power.

so a resistor to regulate the LED current?
are these high power LED's?
have you calculated the power dissipation in the resistor?

or are you just talking about "dimming" them and not "driving" them.
 

sk8ter20art

New member
They are 3w high power leds. And I will be using a tip120 transistor (not resistor) to pwm the leds from the 12v power supply, the arduino will be controlling the pwm of the transistor for dimming control. Will have 4 transistors set up total one for each color.
 

dread240

New member
I am seriously confused as to what you're trying to accomplish here...

I see in your sig a 75g DT... that's what I have.. I have 96 LED's over my tank.. that would require 24 circuits assuming I had 4 LED's on every 12v circuit

Why not do something like a meanwell 700ldd-h (or a 1000ldd-h) on a 48v power supply, which allows up to 16 LED's per string (4x what your setup is describing) and all it requires is a pwm signal to a single pin of the driver (which is nothing more then an analogWrite command in arduino on a pin)

Further I see you mention a 12v 2a power supply... well even if you're talking bridgelux led's they max around 700ma (670 if i recall) so that's only enough power for 12 LED's.....

(rough numbers but kinda standard)

forward voltage : 3v
current : 700ma

4 led's forward voltage : 4 x 3v = 12v
3x 700ma strings = 2100ma 2.1a
 

dread240

New member
for reference... my tank required a 7.3a 48v power supply (that's 350w worth of power for LED's)

you're looking at only 24w worth of power (12v x 2a = 24w)
 

sk8ter20art

New member
This is not for my 75gal. This for my 20 gal (mentioned in first post). I am am going for a cheap high power led setup with an automatic on/off and dim cycle. I already have a marineland led light that was 50 bucks and is a p.o.s.

I am about $600 short on parts for my 75gal setup so its not even ready yet.

I am at work now, will post some type of diagram later for review, also the power chord I already had, can change if needed.
 
Last edited:

sk8ter20art

New member
ok here is my crude diagram of what i am trying to put together. please forgive me if I have made any newbie mistakes:headwally:. i may add 2 whites to the center cluster depending on final looks, haven't gotten to the point to test it out yet.

Oh and thanks for all the help by the way.:thumbsup::thumbsup::thumbsup:

led info

white:3w, vf 3.5-4, 700ma
blue: 3w, vf 3.2-3.6, 750ma
red: 3w, vf 2.1-2.4, 700ma
uv: 3w, vf 3.2-3.8, 700ma

power supply i have on hand 12v 2A (similar to laptop charger), may also have a laptop charger somewhere might be a different voltage/amp.

diagram i copied for dimming control of leds.
ledwiring_zpsdb743b75.png


my crude wiring diagram for whole setup, I have 3 heatsinks one for each cluster approx 3x3inchs.
layout_01_zps13ece4db.jpg
 

mcgyvr

New member
Its full of newbie mistakes
it won't work at all.
An LED is NOT a lightbulb.. It needs to be powered by a current limited supply.
Also the sum of the max forward voltage of an LED series string must be less that the power supply voltage.
I smell smoke in your future.
 
Last edited:

sk8ter20art

New member
ok well i did some digging around and found the laptop power supply that i have. The laptop power supply is rated at 19v 3.16A. Based on my led diagram below what would you recommend for powering my leds? Keep in mind i am trying to keep this cheap and compact. I will be using the arduino to control the pwm of the leds, so i can have an auto day/night cycle. I would like to include the arduino 6-9v and 2 small 12v .13a fans.

also i just realized i did not draw in the power connectors for the upper string of white leds (yellow)

2x 4 white leds -day only
3 blue leds -day and night
2 red leds -day only
2 uv leds -day and maybe night (will have to see)

I would also like to ask how running leds parallel affects the power usage?

led_wiring_zps1b63f81d.jpg
 

dread240

New member
First... that color rendition will be pretty terrible... but even with what you have there...

36v power supply and 4x meanwell ldd-700l

The 700l driver's can be found for as little as $3.70/ea... your diagram up there shows your largest string as 8 4v led's... so the 36v supply gives you the required overhead for the 32v demand to have them all on one string... dimming and control is ridiculously simple with a simple analogwrite command from an arduino to the pwm input.... coupled with a rtc and you can program any light cycle you want with it

If you didn't mind a few bucks more, and wanted room for expansion down the road... then a 48v supply with meanwell ldd-700h drivers will work perfectly fine in this application too, and allow you to add even more led's per string down the road if you feel the need
 

sk8ter20art

New member
First... that color rendition will be pretty terrible... but even with what you have there...

36v power supply and 4x meanwell ldd-700l

The 700l driver's can be found for as little as $3.70/ea... your diagram up there shows your largest string as 8 4v led's... so the 36v supply gives you the required overhead for the 32v demand to have them all on one string... dimming and control is ridiculously simple with a simple analogwrite command from an arduino to the pwm input.... coupled with a rtc and you can program any light cycle you want with it

If you didn't mind a few bucks more, and wanted room for expansion down the road... then a 48v supply with meanwell ldd-700h drivers will work perfectly fine in this application too, and allow you to add even more led's per string down the road if you feel the need

i meant to draw the whites as 2 strings of 4, dont know if that would change much as far as power requirements.

What kind of amperage would the power supply need to be? if i were to use the 4 700ma meanwells, 2.1A or higher?
 
Top