PICO's DIY Thread - Advise, Ideas and Technology - NO PANEL REPS!

[PICOGRAV]

For clarification, when looking for LED drivers. To run one Vero 29 I need 39v and 3.1a. To run two, Would I need 39v and 6.2a

This is right, they might use anywhere from 38 volts up to 45 volts to pull that current, depending on temperature and age. You really do need the sense terminals connected yes, you will have no control over the voltage if you don't, with out them you are always in constant current and would be able to drive the LEDs but you would be, like driving them blind.

I think once the sense's are connected everything will become clear, proper adjustment should be like this, turn all the knobs counter clock wise to zero, first middle out the fine volt and amp adjustments. Next give the amp "Course" knob a quarter turn clock wise, then work your voltage up from the "Course" voltage knob until the LEDs illuminate, keep increasing the voltage until you hit the current limit set be the quarter turn on the amp knob, once the you hit the set current limit DONT increase the voltage yet, LEDs will be very dim at this point. What you would do now is go another quarter turn or maybe a little more with the amp knob and then increase the voltage again, keep doing this until you reach the correct amps. At this point bring back the current by turning the course current knob counter clock wise just until you are on the edge if the current/voltage limiter. Now you have a dialed in current and you should leave the current knobs alone for the rest of operation, you can dim with just the voltage, always bring the voltage up and give it about a quarter turn past the current limit, so it will take up the slack if the LEDs resistance drops.

I would not dial in the LEDs with the constant current control, its a much more rudimentary system compared to the way the voltage is regulated and you will see, jumps up and down quiet sporadically.

I think the fan should be replaced, if you want to do some extended tests, maybe take the old one out and mount a DC fan on the outside of the case with a small external power source, the cross flow air is needed to cool sensitive components of the Power Supply system.

 

[PICOGRAV]

If you run them with 6,2 Amps you have to run them in parallel then the the amps gets split to 3,1A each. In this case, if one led Fails then you suddenly run the other led with the hole 6,2A which might destroy it too....so imo you should run them with 78V and 3,1A in series...if one led Fails it might get "dark" because the circuit is disrupted...but the other led wont take damage

Lax I know your heart is in the right place but...

You would actual run the risk of "Destruction" of of both the LEDs when one fails, running them in series rather then parallel. Having them in Parallel creates two closed circuits from the power supply out put instead of one, if one did fail the other would be un effected, unless it damages the power source.

Running any LEDs in series is not as easy as you would think, the variable resistance complicates the load through a single circuit, the LEDs are all independent of each other and if one LEDs resistance goes up, it will bring a constant current source voltage up with it, whitch will in turn dump the extra amps into the LED with a lower resistance, you can help stop this by running parallel resisters with the LEDs but then you are wasting power.

Lax, I still love you and I am going to get fuking high right now!

 

[lax123]

Pico, last time I asked you this:

I sent him Pictures of the Panel and the led. He said that my led prolly got damaged because im driving it in series with other leds of different Forward voltages.
XMLU2 has 12 Vf, while im using it in combination with 3,3Vf CW and 3,4Vf blue etc.
I explained to him, that that would be no Problem and anyways every led Vf is a bit different and so on and that im driving it at 650mA instead of 1000mA, so that it actually should last longer etc...
Using a Driver with 36V-76V and 650mA. Combined Vf about 50V.

Am i wrong? That would would be a really hard hit for me lol

You also said ist complicated etc:

Normally you could calculate the resistance of the load and then work from that but I dont think that information is available and it changes depending on heat and voltage as well.

But then guod said to me:

your calculation and thinking is right.

Then I also asked JMD, Master of Electronics degree, he also said im right... I asked you to Show me links or sources that are explaining what you are saying...can you give me those? Pico when you just Google: led series parallel.... you will always find to rather NOT to drive them in parallel but to drive them in series with a CC. Please Show me otherwise. Is it maybe that you never realized I was talking about doing that with a CC Driver?

 

[PICOGRAV]

Pico, last time I asked you this: You also said ist complicated etc: But then guod said to me: Then I also asked JMD, Master of Electronics degree, he also said im right... I asked you to Show me links or sources that are explaining what you are saying...can you give me those? Pico when you just Google: led series parallel.... you will always find to rather NOT to drive them in parallel but to drive them in series with a CC. Please Show me otherwise

I'm sorry Lax but your experiment when you drove all the LEDs in series is a perfect example and proves why its a bad idea, one of you LEDs became over driven in the circuit because it was becoming saturated with current.

Most LEDs are low voltage and it is difficult to drive say, 100 leds all in parallel, so most systems use mostly series stings, LED manufacturers do take this into consideration and design somewhat a balancing circuit into high power LEDs but these decreases the efficiency slightly, this could be a consideration when choosing an LED diode for an array. The COBs I am using are just a bunch of series and parallel strings, with well designed junctions (where they connect), very special care is taken when designing these junctions, they need to have high resistance stability at various temperature ranges and there physical placement on the die is very very important, they have to prevent current runaway in-between each LED diode on a microscopic level. This should be another consideration when selecting the very best LED Array.

 

[lax123]

I'm sorry Lax but your experiment when you drove all the LEDs in series is a perfect example and proves why its a bad idea, one of you LEDs became over driven in the circuit because it was becoming saturated with current.

I bet you are wrong. Please Show me atleast one Google/WWW source... Also i think this is wrong:

Most LEDs are low voltage and it is difficult to drive say, 100 leds all in parallel, so most systems use mostly series stings

Its the other way around! They would drive 100 leds in series if they could, but 100leds Need e.g. 400V and thats not easy to achieve on the one Hand and on the other Hand you dont wanna be around those 400V and 1Amps, so there are safety issues...so they splitt them up in parallel. And since you cant crank up that Voltage as you please, you would have to use several CC led Drivers...but that increases costs, so its cheaper to drive them in parallel with a higher current Driver. Please provide sources that say otherwise...

 

[MrFlux]

Lax I read that one of your diodes in a series string blew up. This can happen if you first plug in the CC driver and then connect the string. The initial voltage of the CC driver can be too high which will cause a current spike when you connect the string. The correct way is to power the CC driver with the LED string already attached.

Btw your understanding is fine don't let yourself be confused.

 

[PICOGRAV]

I bet you are wrong. Please Show me atleast one Google/WWW source... Also i think this is wrong: Its the other way around! They would drive 100 leds in series if they could, but 100leds Need e.g. 400V and thats not easy to achieve on the one Hand and on the other Hand you dont wanna be around those 400V and 1Amps, so there are safety issues...so they splitt them up in parallel. And since you cant crank up that Voltage as you please, you would have to use several CC led Drivers...but that increases costs, so its cheaper to drive them in parallel with a higher current Driver. Please provide sources that say otherwise...

I am the source.

 

[lax123]

Lax I read that one of your diodes in a series string blew up. This can happen if you first plug in the CC driver and then connect the string. The initial voltage of the CC driver can be too high which will cause a current spike when you connect the string. The correct way is to power the CC driver with the LED string already attached.

Btw your understanding is fine don't let yourself be confused.

Yea, this happend after 2 months of my Panel running 18hrs a day. So no wrong connecting there...Also i think i would actually be too scared to wire that all while its running lol, except its a 12V pc fan. I read that usually a led Fails withing the first some 1000hrs or something like that usually if not it will last very Long. I hope thats the case and my other +80 leds in series (3CC drivers)go all the way

I am the source.

Ok, i give up. I just hope you dont help a newb here resulting in blowing himself up...

 

[Frosty69]

ok so i made my first led ligght and i used 660nm and its really red. well im about to order more leds for my second light but i wanted to get some opions on what you thought before i buy. i am planning on doing a led light bar and i want to do a strip of 14 maybe 15 if i my driver can handle it.

im planning on using this driver http://www.rapidled.com/mean-well-lpc-35-700-constant-current-driver/

3 of these http://www.mouser.com/ProductDetail/Osram-Opto-Semiconductor/LCW-W5AM-JZKZ-4O9Q-Z/?qs=/ha2pyFadujmOZQbPThBemLXPXLRBcvMbzT28Yra2eR7oE%2buYDSbnZK%2b7qXtO2BJ

1 of these http://www.mouser.com/ProductDetail/Osram-Opto-Semiconductor/LD-W5AM-3T3U-35-Z/?qs=/ha2pyFadujxvV9KtwBXXOy7tCuSuR6cRbK3YEq3sAFmkxkdZJDcVQ==

and ten of these http://www.mouser.com/ProductDetail/OSRAM-Opto-Semiconductors/LR-W5AM-JXJY-1-Z/?qs=sGAEpiMZZMu4Prknbu83y2bVDy/fnbrN2x3W5FW4oSc=

are these good leds or are there better ones i should be looking for?

thanks for the help

 

[PICOGRAV]

ok so i made my first led ligght and i used 660nm and its really red. well im about to order more leds for my second light but i wanted to get some opions on what you thought before i buy. i am planning on doing a led light bar and i want to do a strip of 14 maybe 15 if i my driver can handle it.

im planning on using this driver http://www.rapidled.com/mean-well-lpc-35-700-constant-current-driver/

3 of these http://www.mouser.com/ProductDetail/Osram-Opto-Semiconductor/LCW-W5AM-JZKZ-4O9Q-Z/?qs=/ha2pyFadujmOZQbPThBemLXPXLRBcvMbzT28Yra2eR7oE%2buYDSbnZK%2b7qXtO2BJ

1 of these http://www.mouser.com/ProductDetail/Osram-Opto-Semiconductor/LD-W5AM-3T3U-35-Z/?qs=/ha2pyFadujxvV9KtwBXXOy7tCuSuR6cRbK3YEq3sAFmkxkdZJDcVQ==

and ten of these http://www.mouser.com/ProductDetail/OSRAM-Opto-Semiconductors/LR-W5AM-JXJY-1-Z/?qs=sGAEpiMZZMu4Prknbu83y2bVDy/fnbrN2x3W5FW4oSc=

are these good leds or are there better ones i should be looking for?

thanks for the help

I like these LEDs, when I first saw the name OSRAM I thought these could be nice, I like the specs, there is not as much info available for these as some other company's provide, but the DATA sheet looks OK.

They will be tricky to mount, have you used this packaging before? How will you be mounting on the bar?

As you you can see here in the data sheet for the Blue and Red, there will be a mismatch between the Vf:

Blue:


Red:


At 700 ma the driver will have to saturate the circuit with at least 3.42 Volts to push through the blue LEDs, this will push the Red LEDs past the rated output causing problems.

If you continue with these LEDs you will have to use two drivers or implement a balancing circuit which will bring in its own losses in efficiency.

You might know this already but I am all about the COB, or LED Arrays but I see why you might do this, for side lighting? If so I can have a look there might be some easier to mount LEDs that are still for the right price, I am also thinking about maybe doing a side LED bar, if I do I will surely post it here.

How did that grow turn out or are you still pushing her?

 

[guod]

I like these LEDs, when I first saw the name OSRAM I thought these could be nice, I like the specs, there is not as much info available for these as some other company's provide, but the DATA sheet looks OK.

They will be tricky to mount, have you used this packaging before? How will you be mounting on the bar?

As you you can see here in the data sheet for the Blue and Red, there will be a mismatch between the Vf:

Blue:
View attachment 2886273

Red:
View attachment 2886274

At 700 ma the driver will have to saturate the circuit with at least 3.42 Volts to push through the blue LEDs, this will push the Red LEDs past the rated output causing problems.

If you continue with these LEDs you will have to use two drivers or implement a balancing circuit which will bring in its own losses in efficiency.

...
?

Bullshit...


@frosty69
For Oslon Gölden Dragon go here

 

[PetFlora]

Posted this on my thread but since you guys are into DIY...

It just keeps gettin better led heat sink

increases thermal conductivity but also directly reduces production costs. In the case of applications that already had inadequate thermal conduction rates and then came to require an active cooling system, the reliance on these active cooling systems can be greatly reduced; reducing the size of these systems or eliminating them altogether will also reduce production costs.

http://www.sinkpad.com/how-sinkpad-helps.php

 

[PICOGRAV]

Bullshit...


@frosty69
For Oslon Gölden Dragon go here

View attachment 2886692

Have fun replacing your LEDs every few months. The potential for destruction is very high in this set up. If you can not grasp the idea if variable resistance inside of the LEDs I don't think you will ever be able to design a great panel.

Here are the calculations for the circuit=

Blue LEDs - normal resistance calculations -r= e/i 3.42V/700ma = 4.885 ohms x 4
Red LEDs - normal resistance calculations -r= e/i 2.5V/700ma = 3.57 ohms x 10

Total Resistance = 55.24 ohms
Total Voltage = 38.668 Volts (E=RxI)

In a perfect world with no temperature differences the voltage drops will be stable across each LED but that is not a practical way of thinking.

Here are the Relative temperature vs Vf;


So as you can see things are not as simple as you would expect, I believe it is possible for this circuit to work yes, but I dont recommend it and I have explained why.

 

[tags420]

http://led.linear1.org/led.wiz

 

[PetFlora]

Now that tiny panel is what I'm talkin 'bout! Hell Ya! How many watts, or does the link provide the 411?

Now imagine another circle of clusters wrapped around this panel/snow flake

Bullshit...


@frosty69
For Oslon Gölden Dragon go here

View attachment 2886692

 

[MrFlux]

http://led.linear1.org/led.wiz

Tags I know you mean well but that wizard is very old (like in tripping over his own beard). It will advise to put a resistor in the LED string. This is not very efficient and leads to all the sort of mist and confusion that you can see going on in this thread. Nowadays most (sane) ppl use a constant current driver.

 

[PICOGRAV]

Tags I know you mean well but that wizard is very old (like in tripping over his own beard). It will advise to put a resistor in the LED string. This is not very efficient and leads to all the sort of mist and confusion that you can see going on in this thread. Nowadays most (sane) ppl use a constant current driver.

Also it dose not even address Frosty69's original question in regard to using a single driver to push current through 3 different types of LED's that have different forward voltages.

I think most of these problems people have are coming from the CC drivers, not having any voltage control is idiotic.

 

[tags420]

Tags I know you mean well but that wizard is very old (like in tripping over his own beard). It will advise to put a resistor in the LED string. This is not very efficient and leads to all the sort of mist and confusion that you can see going on in this thread. Nowadays most (sane) ppl use a constant current driver.

It applies to CC drivers and still works figuring out driving the same chips with one driver(Like how many could this driver drive?). The problem with using different chip company/models is the variable between fV, but that's just part of the game. Most of the time having them on separate drivers is the only/best way. Doesn't mean they have to be the same model drivers for everything...only what the series/parallel/array calls for with the selected chip.

Running different COB's would have the same issues.

Why do you not have to use resistors with CC's. If the chips don't fit the driver perfect then there will be some excess voltage right, what happens with it?

 

[PICOGRAV]

It applies to CC drivers and still works figuring out driving the same chips with one driver(Like how many could this driver drive?). The problem with using different chip company/models is the variable between fV, but that's just part of the game. Most of the time having them on separate drivers is the only/best way. Doesn't mean they have to be the same model drivers for everything...only what the series/parallel/array calls for with the selected chip.

Running different COB's would have the same issues.

Why do you not have to use resistors with CC's. If the chips don't fit the driver perfect then there will be some excess voltage right, what happens with it?

The driver constantly varies the voltage its supplying to the circuit, if the LEDs heat up the resistance normally drops, so you use less volts to push the amps through, if the LEDs cool down, normally the resistance will go up so you need a higher voltage.

In my setup, when the LEDs are cool from the night cycle, I need about 41 volts to get the 3 amps~ per LED, when the system warms up, this drops to about 39.6 volts. The hotter everything gets the less voltage I need to apply to the COBs to get the rated amperage.

It is still a good idea to use resistors to balance long series strings of LEDs.

 

[PICOGRAV]

Also looks like the mods are playing favorites, I specifically made this thread so I could speak my mind and now I am being censored, there is more then enough warning in my first post to warrant my reply's and I had never been told it could not go down like this. I have seen worse then what I wrote many times on this forum...

Can you please restore the integrity of this discussion?

EDIT: if anyone would like to see the actual reply I made to stardustsailor, just PM me and I will send it to you. It must have hit a fuse or something, I dunno?