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Inspired by PaulB but failed. Need help with DYI LEDs

Lostinthedark

Lostinthedark

NJRC Member
I took apart my old Ocean Revive S026 and tried to use the parts to make a six foot long LED bar to compliment my T5s. I wired all the LEDs together in 2 groups of 24 just as the lights were. I checked them with a pair of "AA" batteries and everything looked great. When I tried to hook up the power supplies the lights continuously flicker as if they are shorting. It happens exactly the same on both sets of 24. I checked all the connections and can't see any shorts. Is there something I am missing? I have a "-" and a"+" going from the power supply to the lights. No ground. The LEDs are hooked up in parallel, + to + and - to - . Seems simple enough. What am I missing?
 
trivan

trivan

I'm no expert, but my guess is your power supply is the issue. I'm guessing the original didn't have the power supply direct to the LED's. Is that what your doing?
If there was a circuit board in between, that board probably regulated the power to make it a constant supply. Many power supplies actually turn on and off hundreds times a sec.
 
Lostinthedark

Lostinthedark

NJRC Member
Yes it was going to a board. I have it going straight to the LEDs. Someone on another site said it had to be wired in series not parallel. I started rewiring it but my soldering iron burnt out.
 
Lostinthedark

Lostinthedark

NJRC Member
njtiger24 aquariums said:
You might be sending too much power to the LEDs.
Click to expand...

I took it off a board with 24 LEDs and hooked it up to 24. I'm not an electrical engineer in the least but am trying to muddle my way through this.
I'm going to try re soldering them in series and see if that works. I burnt out my soldering iron last night so have to get a new one.
 
redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
I'm prefacing my comments by letting you know that I don't know what I'm talking about. However, what little I do know is that you can't simply flip series and parallel connections. Without changing the power source, you need to set up those LEDs how they were set up in the original fixture. Simply put, a parallel circuit gives every device (LED) on that circuit the voltage coming from the power supply. On a series circuit, that voltage is "shared" by each device, and if I assuming the same resistance on each device, the voltage to each device is determined by simply dividing the volage by the number of devices. As an example, a power supply putting out 48 volts, with LEDs arranged in parallel, each LED would recieve 48 volts. When set up in series, and assume 24 LEDs, each LED recieves 2 volts.

That being said, the first thing that came to my mind was how you had these LED's mounted. If they are LED beads, and they are mounted on a conductive metal, could you be gounding them out (shorting out) because the positive and negative sides of the bead are contacting the metal mounting piece? If you have a multimeter, this is easily checked.
 
Lostinthedark

Lostinthedark

NJRC Member
They are on aconductive surface but I tested them with 2 batteries and they all lit up. How did PaulB attach his to his copper pipes? Did he use a insulator?
 
redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
I'd be willing to bet your issue is that you are shorting out / grounding out the beads.

I went back to Paul B's build and you can see he mounted the beads on a disc of copper, allowing the positive and negative leads to be soldered separately (not contacting the copper):

2015-02-02%2000.24.42_zps3zuq75hv.jpg



If you mounted your beads directly on a flat stock, and then soldered them, the solder most likely contacted the flat stock and now shorts out the beads. The reason the battery check worked is that I'm sure you were only checking one bead at a time....and therefore it would work fine. But once you energized the whole thing, beads grounded / shorted out. That's my guess, and I'm sticking with it.

Again, a multimeter would immediately identify if this is the issue.....you can pick one up at Harbor Freight for cheap....maybe about $5.

image_11746.jpg
 
redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
If your problem is that the positive and negative leads are contacting the flat stock, I just took an old bead and found that you can bend up the leads. That's a potential fix, if that's your problem.

 
saltkreep88

saltkreep88

Also make sure you are thermal compound and that the one you pick is not very conductive. If you didn't use compound your leds will burn out very quickly and if the compound is high conductive like some are that could make the shorting issue above worse.
 
Lostinthedark

Lostinthedark

NJRC Member
Its a total of 55 Mixed blue from 420 to 480. Very little effect with the ATI 8x60 T5s on. I was looking for a little more "POP".

At least all it cost me was time. I had all the pieces to try it. Makes a beautiful sunset effect though.
 
redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
Glad to see you've got it figured out. If your interested, the blue beads I purchased off eBay were 453 nm. I paid $20 for 50 beads, and I just looked them up and they're down to $16, free shipping.
 
Paul B

Paul B

NJRC Member
I was here a few months ago and a few decades ago. I just don't read every post on every forum so I missed it. You could have PMed me. :grin:
 
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