swimmer4uus
Member
48"
I saw another build on nano reef that the guy has 2 20" long heat sinks. Pretty impressive
DIY LED questions
- Thread starter swimmer4uus
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48"
I saw another build on nano reef that the guy has 2 20" long heat sinks. Pretty impressive
swimmer4uus
Member
Another question. Is there such a thing as a 1 ohm potentiometer? Well, one that ranges from 1 ohm up to maybe 10 ohms?
swimmer4uus
Member
Got the first half of the LEDs on the heatsink. Tomorrow I'll get some more wire to solder them together. I've got an essay due tonight otherwise I'd try to get them done. Still waiting on my POTs, resistors, thermisters, and the blues.
swimmer4uus
Member
Standard 90g acrylic. Soon after getting the lights finished, I plan to buy a decent sized carpet anemone. I just want to make sure I have enough light for it.
swimmer4uus
Member
Well it's getting closer and closer. Tomorrow I'll do some work on it before I head to work. Maybe. I have a pretty important midterm on Thurs. Friday I for sure have off of work, so hopefully by then my last resistors will come in and I can start soldering up the driver circuits. Once those are done, it will be time to fire up all the LEDs at once.jy
arty:
I need to figure out what's up with my soldering gun/probe. I'm melting a lot of the wire's plastic insulation. Tested with cutting away more, but I don't like how it looks with wire showing.
arty:I need to figure out what's up with my soldering gun/probe. I'm melting a lot of the wire's plastic insulation. Tested with cutting away more, but I don't like how it looks with wire showing.
swimmer4uus
Member
If only I didn't have homework due.
swimmer4uus
Member
So figured I'd share some pictures of the drivers I wired up. First shows the configuration of the back side of the PCB, and how I bent/will solder up the wires. The others just show different steps.
NOTE: Wired up the mirroring LM317's wrong in the above picture. Wow, that's what happens when you rush it
So here's one with the correct wiring.
NOTE: Wired up the mirroring LM317's wrong in the above picture. Wow, that's what happens when you rush it
So here's one with the correct wiring.
zigginit
Member
so you are making your own drivers? it looks like you know what your doing but i dont know anything about that so i cant tell. how did you learn how to make them? is it as simple as that and what is the rating on the driver? i would be intrested in doing this myself if i can understand it better. and how much dose each one cost?
swimmer4uus
Member
Yes it's easier, a little cheaper, but you have to do the math with it. The LM317 version is not as efficient as say buckpucks, but it's cheap, and very easy to do. Google LM317 constant current driver.
swimmer4uus
Member
Now, for compairison. The first picture shows the LEDs on. In the background is the window in the kitchen, open, with a bright and sunny day outside. That's how bright these babies are
swimmer4uus
Member
Well the final wiring isn't completed yet. I still have to solder up all the second half of LEDs on the other heat sink, as well as get them hooked up to drivers. I'm looking for a quick connect to make this thing really a plug and play. Almost like the connectors used on mp3 players, headphones and such.
Here's the adjustable driver I made. Simple setup. The switch makes the driver go from 1050mA to 520mA
Also here's with the heatsink flipped over.
One string wasn't connected hence them not being on.
The connections where made with the aligator clips. I'm not too sure how I'm going to do that in the end, but I'll be sure to update
Here's the adjustable driver I made. Simple setup. The switch makes the driver go from 1050mA to 520mA
Also here's with the heatsink flipped over.
One string wasn't connected hence them not being on.
The connections where made with the aligator clips. I'm not too sure how I'm going to do that in the end, but I'll be sure to update
zigginit
Member
so am i looking at 4 drivers on one project board? why are the 2 in the middle laying down? i like the way that you did this and would like to know a really dumbed down explanation of what im looking at. is that all thats in a driver 4 resisters and whatever that black thing is? (what is it). nice build so far.
swimmer4uus
Member
Yes, you are looking at 4 drivers on one board. The two in the middle are laying down because I messed up on my first two, so I had to cut their lead wires. When I made that protoboard I only had those left so instead of waiting, I salvaged those.
As far as drivers are concerned, this is very timid. First off I did a couple calculations to figure out how exactly I could make something like this. I (at the time) only had 1.2 ohm resistors. I wanted the switch to go from basically half power, to full power. I put 2 resistors in series, effectively making one 2.4 ohm resistor. Then put two of those in parrallel. (Math wise all I did was take 1.2 times 2, then divided by 2) Now, with the switch to the left, all the current goes through the left 2 resistors in that driver circuit. When the switch is to the right, the current is divided and goes through all 4. Short version, the switch makes the 4 resistors combine for 1.2 ohm resisitor, and 2 resistors for 2.4 ohm.
Here's what a single driver circuit would look like, with only one resistor.
Now as far as getting the LEDs up and running, the LM317 will do just fine. I'd personally recomend having a smaller current driving the LEDs, as I went for 1000mA, and the 317 gets HOT! Hence me probably not using these, and also hence the delay for this getting on my tank.
I've been reading on reef central the DIY driver thread. Although I won't be using the same configuration (they are running Boost Topology), since my array is already wired at 5 LEDs in series, I'll be building a buck topology using the NCP3066 chip.
This is basically my circuit, what you'd find in the data sheets for the NCP3066.
As far as costs go, its pretty close to the LM317, and honestly I should have gone this route first. BUT, it was good learning.
Here's my BOM, just ordered today.
I'll be sure to update as I make my first prototype. Oh yeah, and Rsense in the circuit is my R1, and Rs is my Rsense
zigginit
Member
wow thanks for the great write up on this. it sure dose seem like you know a thing or two about doing electrical work. wish i could learn more about it. what is the ADJ on the first pic mean and why dose it jump in line past the resistor? dose the negitave end just go from LED to power supply again?
swimmer4uus
Member
Well, I'm at the begining stages. If you had a chance to ask my girlfriend, I'm sure she would tell you how much I read up on stuff like this. Also, I'm a mechanical engineering major and some of the basic courses we have to take are electrical circuits.
So, for your question, the LM317 has 3 pins. Here's a picture for you to reference to.
So from left to right we go Vin, Adj, Vout
The Adj pin must be connected to the output wire AFTER the resistor because...well because. The internal circuitry will basically let all the current you can feed to this thing through, and it'll end up overheating, and shutting down. BUT! With the resistor and the Adj wire connected, THEN hooked up to your LED string, the LM317 will regulate voltage(and indirrectly current), to what you set up the resistor value to. Simple calculation really. You take 1.25 and divide it by what current you want to drive your LEDs at. So, if you want 750mA on your LEDs, 1.25/.75 = 1.7777 Ohms. (750mA = .75A) You must divide by amps, not miliamps. There's some other stuff associated with the LM317, but not much else. You can get the parts at your local Radio Shack if you want to try it yourself.
Here's a picture to look at of a simple tester I found online
And some other circuit someone used the LM317 for. Note the black heatsink. The LM317 when driven close to 1A will get VERY hot.
zigginit
Member
ok thanks again for taking the time to explain this to me. i really love this kind of thing and want to get more into it. i think its good to know this kind of stuff.
so i see your calculations above and have a question. so you want to drive at 750ma so you used 0.75A. the 1.25 was the resistor you used. what does the 1.777 mean? what roll does that number have in this? isnt 1.777 Ohms more then the 1.25 resistor you put on it? is the differance between the 1.25 and the 1.777 mean something?
so i see your calculations above and have a question. so you want to drive at 750ma so you used 0.75A. the 1.25 was the resistor you used. what does the 1.777 mean? what roll does that number have in this? isnt 1.777 Ohms more then the 1.25 resistor you put on it? is the differance between the 1.25 and the 1.777 mean something?
swimmer4uus
Member
Sorry, I forgot to label the 1.25. The full equation is 1.25V/R=Your current.
I used a 1.2 ohm resistor so 1.25/1.2=1.04 which is why they are running super hot. They're at 1000mA.
1.7 would be the resistor you would use to get 750mA. The higher the resistor, the lower your current will be. It's an inverse relationship