DIY modular led with arduino controller
- Thread starter Metalsniper
- Start date
It's been a long time since I did any Arduino research, but I seem to remember an issue with the Arduino PWM output voltage not matching the inputs of the LED driver. The Arduino PWM output is 5V, and the Meanwell "P" driver needs 10V PWM input. Unless you're comfortable building simple electronic circuits, you may want another solution. You only need a transistor and resistor for this one. The difficult part is soldering without damaging the components with too much heat. Simple transformers don't respond quickly to sudden voltage changes needed for PWM.
The good news is that the Arduino code is freely available all over the Internet for dimmer applications. As far as boards, I'd recommend the Mega because of the extra memory.
I have an alternative. Consider multiple LED circuits on separate timers. It worked well for me. You can have a couple blue strings and a couple of whites. Have the blues timed to come on say, an hour apart in the morning, followed by the whites. Then reverse the order for the power-off times.
Here's a thread that has the transistor schematic to convert from 5V to 10V. Scroll to the bottom. https://sites.google.com/site/caddnima/myreeftank/led_controller
The good news is that the Arduino code is freely available all over the Internet for dimmer applications. As far as boards, I'd recommend the Mega because of the extra memory.
I have an alternative. Consider multiple LED circuits on separate timers. It worked well for me. You can have a couple blue strings and a couple of whites. Have the blues timed to come on say, an hour apart in the morning, followed by the whites. Then reverse the order for the power-off times.
Here's a thread that has the transistor schematic to convert from 5V to 10V. Scroll to the bottom. https://sites.google.com/site/caddnima/myreeftank/led_controller
The sample parallel circuit shown in the diagram has serious flaws that could result in burning up all of the LEDs. Pretty graphics do not mean good circuit characteristics. The use of fuses in a parallel LED circuit is a very bad idea, and I'm not sure why they used 1 ohm resistors. They don't provide any branch circuit protection whatsoever.
You're much better off with a single series circuit and no resistors or fuses.
What are the voltage and current requirements for each LED?
You're much better off with a single series circuit and no resistors or fuses.
What are the voltage and current requirements for each LED?
Crit21, I've got some experience under my belt doing through hole soldering and small electronic work so no worries when it comes to soldering a simple circuit. In terms of the 5V to 10V bump circuit there are numerous plans out on different forums to solve that very issue. For example there is a rather comprehensive LED controller that covers this exact issue over on the EVIL EMPIRE. The other alternative is the typhon controller that I wrote about earlier; it is based off the arduino with the ATMega328 chip, which offers both 5V and 10V PWM dimming.
The purpose of the 1 Ohm resistors is to measure the current through parallel branches to ensure that they are pulling the same current and one doesn't go into cascade failure from overdriving one strand.
Why do you say that fuses in a parallel circuit is a bad idea? The fuses are there in the case of a LED failing and causing an open circuit on one strand, resulting in the other strand getting all 1400mA instead of 700mA. In this situation the fuse blows and prevents the failure of both strands.
The reason I want to build a controller is partially just for the experience of having done so, and also because I want to be able to have more complicated sunrise/sunset. I would prefer the LEDs turn on slowly instead of just OMG FULL ON, OMG FULL OFF. That's kinda the purpose of going with a dim-able driver and LEDs in the first case.
Just because you asked here is the info on each LED
Turquoise: Vf is about ~3.5V with a max driving current of 1000mA but recommended 700mA
Red: Vf is about ~2.5V with a max current of 1000mA but recommended 700mA
Royal blue: Vf is ~3.0V with a max current of 1500mA I think, running it at 700mA
Blue: Vf is ~3.6V with a max current of 1000mA but recommended 700mA
True Violet: Vf is ~3.6V with a recommended current of 700mA but a max of 1000mA
Cool white: Vf is ~3.5V with a max current of 1500mA running it at 1000mA
Neutral white: Vf is ~3.5V with a max current of 1500mA running at 1000mA
I think I got those all right.
The purpose of the 1 Ohm resistors is to measure the current through parallel branches to ensure that they are pulling the same current and one doesn't go into cascade failure from overdriving one strand.
Why do you say that fuses in a parallel circuit is a bad idea? The fuses are there in the case of a LED failing and causing an open circuit on one strand, resulting in the other strand getting all 1400mA instead of 700mA. In this situation the fuse blows and prevents the failure of both strands.
The reason I want to build a controller is partially just for the experience of having done so, and also because I want to be able to have more complicated sunrise/sunset. I would prefer the LEDs turn on slowly instead of just OMG FULL ON, OMG FULL OFF. That's kinda the purpose of going with a dim-able driver and LEDs in the first case.
Just because you asked here is the info on each LED
Turquoise: Vf is about ~3.5V with a max driving current of 1000mA but recommended 700mA
Red: Vf is about ~2.5V with a max current of 1000mA but recommended 700mA
Royal blue: Vf is ~3.0V with a max current of 1500mA I think, running it at 700mA
Blue: Vf is ~3.6V with a max current of 1000mA but recommended 700mA
True Violet: Vf is ~3.6V with a recommended current of 700mA but a max of 1000mA
Cool white: Vf is ~3.5V with a max current of 1500mA running it at 1000mA
Neutral white: Vf is ~3.5V with a max current of 1500mA running at 1000mA
I think I got those all right.
Nah, the current issues aren't too bad. I run the two "blue" strings at 700mA and the one white string and 1000mA in order to keep them cooler. I could have probably gone higher on both but why? this is only a test fixture anyway. It'll probably end up over the frag tank when we finally get it set up. If my tap ever shows up I'll finish it up then bring it to the meeting at the firehaus(sp?) so people can see what the colors look like. Unfortunately since the demo is so small its not likely to be enough light for a standard sized tank.
All of the LEDs are not from cree though, only the whites and royal blues are I think. The "exotic" colored LEDs are from ledgroupbuy.
All of the LEDs are not from cree though, only the whites and royal blues are I think. The "exotic" colored LEDs are from ledgroupbuy.
Metalsniper, I don't know what your background in electronics is, but you have all the right answers. I think you'd be much happier in the long run if you can use series circuits using drivers of the desired current. They're much more straightforward, and if an LED fails, the circuit is open and you don't have to worry about runaway or fuses.
I've used low value resistors when measuring current in parallel circuits. They're usually not kept in the circuit long term though, unless you want a permanent test point. Keeping in mind that a resistor has a voltage drop, they will subtract from the overall voltage drop across the LEDs in the circuit. Sometimes that's a desired effect so that you don't exceed the LED voltage ratings.
The resistor in each branch needs to be rated to handle the current and wattage. Assuming you have 2 parallel branches with 1A in each branch, the resistor must withstand 2A after one branch fails, and until the fuse blows in the second branch. Since that would require a 2W resistor minimum (2A through a 1 ohm resistor = 2W), the recommendation of a 3W resistor is correct.
Good luck with the Arduino. It sounds like fun.
I've used low value resistors when measuring current in parallel circuits. They're usually not kept in the circuit long term though, unless you want a permanent test point. Keeping in mind that a resistor has a voltage drop, they will subtract from the overall voltage drop across the LEDs in the circuit. Sometimes that's a desired effect so that you don't exceed the LED voltage ratings.
The resistor in each branch needs to be rated to handle the current and wattage. Assuming you have 2 parallel branches with 1A in each branch, the resistor must withstand 2A after one branch fails, and until the fuse blows in the second branch. Since that would require a 2W resistor minimum (2A through a 1 ohm resistor = 2W), the recommendation of a 3W resistor is correct.
Good luck with the Arduino. It sounds like fun.
I have 240 LEDs driven by 4 drivers. Split into 5 strands on each with 12 LEDs in each strand. Other then a couple failed LEDs I have had no problems.
For the larger tanks building only in series is not an option.
If its done properly, parallel builds are fine. And metalsniper has a good plan and everything in order.
I also stated my build with the ardurino but ended up going with an apex. I actually have spare boards if you need them. Found it too much work and so I just went with a commercial product instead.
Sent from my HTC Incredible
For the larger tanks building only in series is not an option.
If its done properly, parallel builds are fine. And metalsniper has a good plan and everything in order.
I also stated my build with the ardurino but ended up going with an apex. I actually have spare boards if you need them. Found it too much work and so I just went with a commercial product instead.
Sent from my HTC Incredible
Crit21, I don't really have a background so much as I like to tinker with everything so I've had lots of practice. However, I don't plan on leaving the resistors in long term after I have the two strands balanced, just long enough to do a high temperature test to make sure I don't get runaway.
thatOneguy1126, Thanks for the vote of confidence. Also, what arduino stuff do you have?
thatOneguy1126, Thanks for the vote of confidence. Also, what arduino stuff do you have?
On the same lines as thatOneguy's comment, generally the reason behind not doing every strand on its own driver is because it is cost prohibitive and it takes up a lot of space. The reason I want to only use two drivers is because if you look at my proposed design earlier, I only have space for as many. I was alternately considering going with a micropowerdirect powersupply coupled with a few buckblocks, but that is still early in the though process.
thatOneguy, if you find the hydra board and shields and are looking to sell them or get rid of them I might be able to take them off your hands. If you find it, is the hydra board already assembled?
thatOneguy, if you find the hydra board and shields and are looking to sell them or get rid of them I might be able to take them off your hands. If you find it, is the hydra board already assembled?