DIY LEDs - The write-up

[TheFishMan65]

Most multimeters require you to move the probe from a voltage/ resistance location to a current. Some have multiple currents location for different max current or AC/DC voltages. Pick the largest DC one available.

With the power off. Disconnect the positive contact of the meawell to the LEDs. Connect solidly the positive meter probe to the positive meanwell. Also connect solidly the negative probe of the multimeter to the LED. Apply power. The current is now flowing through the meter.

I hope this helps.

 

[kcress]

If you overdrive the wart (if I am reading you correctly) you may fry the wart. Don't try and pull 3.75 amps out of a wart meant to supply 1.2 amps. It gets really hot and quits working. I don't understand it - the magic smoke didn't come out?

Hi Fishman. Any wallwart that is even vaguely legal has to have a fuse in it to prevent wall fires when the loads they are hooked to or doltsD) overload them. The fuses are never replaceable.

Hey and thanks for the summaries. The only thing you seem to have missed was the stacking up of non-PFC drivers. We don't want someone's house burned down due to a DIY LED luminare.

 

[HeneryH]

Paralleling LED Strings – NOT RECOMMENDED

Mine parallel strings work fine. I run three Meanwells each with three strings in parallel. I never tested or balanced the Vf, just fired them up and they run well balanced to the eye.

 

[TheFishMan65]

kcress,

I would have thought it would blow sooner than 2-3 hours. I got a LCD monitor and power supply at a yard sale. The connectors matched so I didn't think any more about it until I didn't have a picture.

Henery,

I didn't say it would/could/should not work. If you understand all the possible failures and designed around them fine. For most people trying to design a system this maybe a bit much on the electronics end IMHO and probably many others

 

[GEORGEDOPE]

Mine parallel strings work fine. I run three Meanwells each with three strings in parallel. I never tested or balanced the Vf, just fired them up and they run well balanced to the eye.[/B][/SIZE]

Henery
More info please. How many LED's on a string and what kind? Do you have fuses on each string, if so what size? What Meanwell are you using? How long has it been running?

 

[HeneryH]

The only extra step I took was to make sure to use three strings so that if one blew then my remaining two would take the extra current.

No extra current balancer circuits or anything were used.

Given I could go back and start over, I'd probably go serial but I had these drivers and went ahead using them. I crossed my fingers and they worked fine thankfully.

They worked so well in fact, that I am wondering if there is some sort of natural balancing going on with the LEDs.

 

[GEORGEDOPE]

Paralleling LED Strings "“ NOT RECOMMENDED


But what other opitions do we have if we want to run 150+ leds and not have 12+ Meanwells that might burn the house down when they start up.
Or have a 240V driver? That would be scary.

 

[TheFishMan65]

That is why I bulid my own driver. Sort of like the buck puck. I think you could find a 24 volt 25 amp (600 watt) supply it would not be cheap. But I found a 10 amp one on ebay with PFC for pretty cheap; so I could use 3 of those.

I agree that there should be a better solution, but I don't know what it is.

I have to ask. If two string blow can the third take all the current (and can you sink the heat)? If not I would add fuses. I believe it will be a lot cheaper than replacing 12 LEDs.

 

[CJO]

Sorry to be such a pest guys but for some reason I'm having way too much trouble finding out how much current my meanwell us producing. I want to run my xpgs at 750mA. Can someone give me a step by step guide on how to measure the current using a multimeter. I think I'm doing it all wrong to be honest and I'm just getting
more confused when I ask a question. Thanks!

How to adjust your LED driver
1. Make sure your driver is connected to power and turned off.
2. Connect the V+ output of the driver to the positive (+) terminal of the first LED in the string.
3. Connect the negative (-) terminal fo the last LED in the string to the positive (+) test lead for your multimeter.
4. Connect the negative (-) test lead for your multimeter to the V- output of the driver.
5. Make sure that the test leads of your multimeter are connected properly (usually the positive [+] test lead needs to be connected to a different jack in the meter than normal) and set the meter to the proper range for testing amps.
6. If you have an adjustable potentiometer inside your driver (such as the eln-60-48d), make sure that it is turned all of the way clockwise!
7. If your driver is dimmable, connect the Dim+ and Dim- wires to the appropriate control source (i.e., connect the eln-60-48d Dim+ wire to a +10V source and Dim- wire to ground).
8. Turn on the power source for the driver. Your lights should turn on and your meter should read the amps being provided by the driver.
9. Slowly turn the potentionmeter in your driver clockwise until your multimeter reads the correct output. For most LED's, this will be between 700mA and 1A.
10. Do not turn off your meter or disconnect it! This could easily blow all of your LEDs. Instead, first disconnect the power to the driver.
11. Now you can turn off your meter and disconnect it. Be sure that you return the leads on your meter to the proper place(s) for reading voltage so that you don't blow your meter the next time you use it!

CJ

PS- hopefully I didn't miss anything!

 

[Jay1982]

Thanks CJ! I think I've grasped about everything you saying. So I put the positive probe on the first led's postive pad, and the negative probe on the last led's negative pad, correct?

 

[jtma508]

CJO...

On #6 didn't you mean counter-clockwise??

 

[stugray]

So I put the positive probe on the first led's postive pad, and the negative probe on the last led's negative pad, correct?

NO.. Imagine putting the whole string together just like you are about to fire it up, now imagine cutting the wire that goes from the last LEDs Negative terminal to the Driver's V- and installing the meter in there as if it were just a wire.

And YES CJO meant turn the SVR2 Pot all the way COUNTER-Clockwise before turning on.

Stu

 

[Obi-dad]

According to Cree, the maximum junction temperature is 150oF.
...
CJ

Good info, but one typo - the max junction temp is 150 C, not F (large difference).

 

[pheinzig]

When you folks are mounting these star boards using drill/tap method...are you using 2 screws or 4?

 

[Jay1982]

NO.. Imagine putting the whole string together just like you are about to fire it up, now imagine cutting the wire that goes from the last LEDs Negative terminal to the Driver's V- and installing the meter in there as if it were just a wire.

And YES CJO meant turn the SVR2 Pot all the way COUNTER-Clockwise before turning on.

Stu

AH! Ok thanks. I can just use both wires that are coming from the meanwell, yes?

 

[akindbro4u]

AH! Ok thanks. I can just use both wires that are coming from the meanwell, yes?

no give me a minute I will upload some pics for you.

 

[westmoorenerd]

Hey thanks for catching that, I re-read the spec's. I was looking at the line above the amp's needed!

Easy fix. Ill order another wart to power them. 2 each would be what....roughly 88% power? My math may be a little off, but im happy with that kind of power out of these puppies.

Running 2 on one wart will run them around 90% max speed which is plenty...you could even run them all one one power supply, it might not give you the speed you need on the fan to cool the heatsinks enough.

 

[Jay1982]

no give me a minute I will upload some pics for you.

Thanks! I really don't understand why I'm not grasping this :lmao:

 

[pheinzig]

Running 2 on one wart will run them around 90% max speed which is plenty...you could even run them all one one power supply, it might not give you the speed you need on the fan to cool the heatsinks enough.

Ill get a second wart for the other two, and eventually Ill by a nice $60 12v powersupply capable of running all 4 plus any extra mods I want to do to the system at a later date.

 

[akindbro4u]

ok setting your meanwell current with a dmm

this is how I have my drivers attached to the led string using a ballast disconnect from tyco.

ok first you power off your driver, then disconnect the coupler as seen here.

next insert your meter in line. You will see here I made a sort of patch cord to do this, but it is not necessary.

you will notice that the ground side is a continuous circuit, and the meter is installed in line with the voltage. . verify all connections, and turn on the driver. Adjust to your desired current.