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My Mouser resistors came in today. With the exception of the 56 Ohm, all are 1% tolerance.

I tried various values and the results were a little surprising.

All of the current value are the measured forward current across any LED. 100mA is the the max rating - we don't ever want to exceed this. Also, cable length is not taken into account (measured values are with 24.0V supplied directly to the MMFL). My power supply can only read current to a 10mA precision. In some cases I show precision to 5mA. This is because I measured total cuirrent across both paths and divided by 2.

Red: 100 Ohms=80mA

Red: 94 Ohms=90mA (94 Ohms was a test with two 47 Ohms in series)

Red: 82 Ohms=100mA

Red: 68 Ohms=120mA <-- 68 Ohms is one of the two values recommended by PDF!

Green: 51 Ohms=95mA

Green: 47 Ohms=105mA

Blue: 47 Ohms=95mA

White: 47 Ohms=95mA

Now, these results differ slightly from my earlier results. One reason is that my previous values were calculated, as I did not have the resistors. The other is that I measured these on the latest batch of LEDs from CeCe.

I should point out that the first batch of Red from CeCe was VERY strange. How strange? Of the 16 red LEDs I received, they were ALL incorrect in some way.

Clear LEDs have three ways to denote anode and cathode:

1) The Flat side of the rim denotes the Cathode (-)

2) The Short lead denotes the Cathode (-)

3) The large triangle terminal in the clear bulb dentotes the Cathode (-)

So back to my 16 Red LEDs...

By the time I made my discovery, I had snipped my legs, so I have no idea if the lead lengths were wrong.

One of the LEDs had the flat side of the rim on the wrong side. Believe it or not, this is not that uncommon.

But the shocker was that ALL 16 had the LED chip installed BACKWARDS! Yup, the large triangle terminal was the Anode.

I had to verify this several times and I still can't believe it.

The latest batch I got from CeCe all look correct, but this should be a lesson to all - Check each and every LED for polarity before you install them. You may be able to do this with a fresh AA battery (if 1.5V induces any light from the LED). Two batteries in series is fine for all LEDs except the Red (3.0V overdrives Red).

So here's the bottom line on resistors - get yourself an array of values and measure against your batch of LEDs.

I now have a nice array of values and many spares. I can package sets of 1W resistors, put them in an envelope and send them to you for a couple of bucks a set. I don't want to make any money on this; just want to cover postage and recoup some of what I spent on them. I have 47 Ohm, 51 Ohm, 56 Ohm, and 68 Ohm. I'm going to also pick up some 82 Ohm.

If I packaged a few of each so you could experiment on the values, I'd have enough for probably 40 kits. Again, PM me if you are interested.

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I rend into the same issues, send them a email about this.

I should point out that the first batch of Red from CeCe was VERY strange. How strange? Of the 16 red LEDs I received, they were ALL incorrect in some way.

Clear LEDs have three ways to denote anode and cathode:

1) The Flat side of the rim denotes the Cathode (-)

2) The Short lead denotes the Cathode (-)

3) The large triangle terminal in the clear bulb dentotes the Cathode (-)

So back to my 16 Red LEDs...

By the time I made my discovery, I had snipped my legs, so I have no idea if the lead lengths were wrong.

One of the LEDs had the flat side of the rim on the wrong side. Believe it or not, this is not that uncommon.

But the shocker was that ALL 16 had the LED chip installed BACKWARDS! Yup, the large triangle terminal was the Anode.

I had to verify this several times and I still can't believe it.

Check each and every LED for polarity before you install !!!

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I noticed on the unit I tested for another member here that the construction of the LEDs themselves looked to be fairly low quality... ironically especially the red which 2 of them had 2 of the 4 dies in each LED were dead from the get go.

Has anyone found a source of good quality LEDs in this form factor?

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If you are experimenting with R valus, and don't really know what the heck you are doing, here's a way to test without soldering and unsoldering the resistor in place:

When you install your LEDs, don't clip the leg on the very bottom row (the pin nearest the edge of the board on R8, G6, B6, W6, etc).

Don't install the resistors.

To test a resistor, solder one end to the un-snipped leg of the bottom-most LED (again, R8, G6, B6, etc).

You can then test the circuit by connecting 24V to the (+) terminal and Gnd to the other end of the resistor (the end that is NOT soldered!).

Example: to test R with Green, solder one end of R to unsnipped G6 (or unsnipped G12). Connect +24VDC to "G+". Connect Gnd to unsoldered end of R. At this point, only 6 LEDs should be lit (8 if you are testing Red). Repeat for other test R values.

If you hook up the power backwards, it will not harm anything - but don't leave it that way for long. If you connect ground to the wrong side of the resistor, you will fry your LEDs (but they will be REALLY bright for an instant, he-he). It must go to the unsoldered side.

When you have the value you like, solder the R in the proper location and snip the remaining LED leg.

Done - nice and neat with no de-soldering.

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I noticed on the unit I tested for another member here that the construction of the LEDs themselves looked to be fairly low quality... ironically especially the red which 2 of them had 2 of the 4 dies in each LED were dead from the get go.

Has anyone found a source of good quality LEDs in this form factor?

I think CeCe has only 1 die; correct me if I'm wrong. I think Topbright sells multi-die.

BTW, how could you tell 2 die's were out? They are too bright to see what is going on inside.

CeCe's Red is definitely low quality. Aside from the problems I mentioned earlier, I saw one Red with an air bubble in the lens. This will shorten the life.

I also had one Green that simply would not come on fully bright.

When you look at these under a high power magnifier you can see that all of the dies are installed at various rotations. Don't know if that's simply a manufacturing artifact.

This out of 2 fully populated boards and 8 more populated only with Red and Green. Still 10 more to go...

Not to be a Debbie Downer, but these issues we are all finding are part of the ballgame when it comes to DIY projects. I'm certain that LOR's XMAS Flood will be a high quality product when it hits the shelves. No doubt that is a big reason why it's taking so long. Wouldn't it be just perfect if we spent all this $$ on the MMFL only to result in varying degrees of success and then to have LOR release their product later this year for $60 each?

Edited by brianfox
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I think CeCe has only 1 die; correct me if I'm wrong. I think Topbright sells multi-die.

BTW, how could you tell 2 die's were out? They are too bright to see what is going on inside.

Just dim it down...LOL!

Wouldn't it be just perfect if we spent all this $$ on the MMFL only to result in varying degrees of success and then to have LOR release their product later this year for $60 each?

We all wish, but I don't think that will be a realistic price knowing what will be in it... kinda... nevermind :rolleyes:

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Hello again. I finally have my cherry-picked R values that work great with my LEDs.

Red: 82 Ohms (100 mA)

Green: 51 Ohms (100 mA)

Blue: 47 Ohms (95 mA)

White: 47 Ohms (100 mA)

The current was observed with a 1 ft CAT5 cable.

I then put a 50 ft cable in place, and the current dropped by 5mA-10mA. So, for typical runs in a display, the forward current should be safe for the LED. But again, this is based on the LEDs that CeCe shipped me - your batch may be overdriven by those values. Do NOT take my R values as the perfect values.

In my testing, the MMFL works really great. The old "floods" I am replacing are simply the clip-ons with the big round aluminum reflector that you can buy from Home Repo. I was using lighting gels and 75W bulbs. I estimate that one color of the MMFL is about the equivalent of a 60W bulb. I imagine that when the glass has condensation or fog on it, the output will be a little less (no heat from LEDs to burn away that fog...)

Green by far had the most intense output, followed by Red and White. Red was by no means dim, een though the LEDs have a very low mcd rating. Blue was rather unexpected. The blue LEDs from CeCe have a surprising amount of fluorescence. Anything white that the blue light touched positively glowed, yet everything else had a royal blue to it. I kind of wish they were more pure blue.

There was a good deal of washout at a 10ft distance; 5ft from my walls resulted in the most uniform spread with no hot spots. I still can't figure out what the heck to do with White in my display. Anybody think about what they will do? I guess I could "strobe" the white for effect. I am using a fixed Power Supply right now so I cannot color mix as I have no controller yet. I wonder if adding white to a color mix will make it brighter or wash it out.

On the subject of CAT5 couplers, the really cheap 50 cent ones were mentioned. I happened to have some of these and I observed that you get what you pay for. The CAT5 male connector had a lot of play in the female coupler, and it was possible to make the LEDs go out by wiggling the connector. In my opinion, this is NOT the way to go, as those couplers come in several flavors: cheap, cheaper, and cheapest.

The RJ45 ECS mating system, on the other hand, seems to be highly reliable. Yes, they are expensive at about $4 each, but I don't feel they will let me down. I do have to say having tried them out - they are not the easiest things to work with. To unmate the connector is a several-step process, and you need a small screwdriver to make the RJ45 connector unclip from the locked position. It is by no means a quick disconnect. But seriously, if you connect it once at the start of the season and disconnect it once at the end of the season, it's not that big a deal. Much better than dealing with an unreliable coupler.

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I still can't figure out what the heck to do with White in my display. Anybody think about what they will do? I guess I could "strobe" the white for effect. I am using a fixed Power Supply right now so I cannot color mix as I have no controller yet. I wonder if adding white to a color mix will make it brighter or wash it out.

I use them in my display. I flash them with my other white lights in songs like White Christmas. Use them as blinders. Use them to light-up your display while you are out fixing your display at night.

On the subject of CAT5 couplers, the really cheap 50 cent ones were mentioned. I happened to have some of these and I observed that you get what you pay for. The CAT5 male connector had a lot of play in the female coupler, and it was possible to make the LEDs go out by wiggling the connector. In my opinion, this is NOT the way to go, as those couplers come in several flavors: cheap, cheaper, and cheapest.

Actually .38 cents is what I pay - don't pay .50 cents! I've done more than observed - I used these cheap connectors last year and they are still working fine today. In fact, they show no signs of corrosion. Even if they did go bad... I could purchase 11 of the cheap couplers for one ECS connector.

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  • 4 weeks later...

Hi All: I just made my first 3 MMs. I love them. I have gone through this thread completely and have not found an answer to my question/comment. I was really surprised at the heat that these things give off. When I tested the first completed board with all of the LEDs on, it got so hot that I almost burned myself. I will show my ignorance and ask if this is normal. When I mounted the MM into the fixture things really heated up. I also started having problems with the LEDs. One or two on each board quit working because of the heat (I guess). I ran a test on the temperature. With everything closed up and the lense cover on, the temperature reached 306 degrees F, right on top of the LEDs. The temperature just under the board but still inside of the fixture reached 120 degrees F. Is this really normal? I realize that for many applications the lights will be off more than they will be on and that you normally will not have all of the lights on at once. Has anyone else had problems with the LEDs breaking down because of the heat? I am having to go back and replace the bad LEDs (yes, I did test them with a tester before I installed them) and that takes extra time.

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Hi All: I just made my first 3 MMs. I love them. I have gone through this thread completely and have not found an answer to my question/comment. I was really surprised at the heat that these things give off. When I tested the first completed board with all of the LEDs on, it got so hot that I almost burned myself. I will show my ignorance and ask if this is normal.When I mounted the MM into the fixture things really heated up. I also started having problems with the LEDs. One or two on each board quit working because of the heat (I guess). I ran a test on the temperature. With everything closed up and the lense cover on, the temperature reached 306 degrees F, right on top of the LEDs. The temperature just under the board but still inside of the fixture reached 120 degrees F. Is this really normal? I realize that for many applications the lights will be off more than they will be on and that you normally will not have all of the lights on at once. Has anyone else had problems with the LEDs breaking down because of the heat? I am having to go back and replace the bad LEDs (yes, I did test them with a tester before I installed them) and that takes extra time.

When using High Output LEDS such as the Strawhats and many others, the do give off quite a bit of heat in the form of light. As far as heat at the board level, the strawhats should still be fine. When I was beta testing a "certain" LED flood 2 years ago, I measured 170 to 200 deg+ the glass with a laser temp meter with all the LEDS on for 10 minutes! This is mostly light generated heat being dispated. Contrary to popular belief LEDS do generate heat. In most cases they are able to disapate it rather quickly. Cramming 50 plus HO LEDS into a small area, you are going to have to dispate quite a bit of heat from the light somewhere.

The temps you saw are actually pretty much normal so do not fret on that side.

The issues of why you are having to replace LEDS has been documented several times. There have been many discussions on this subject, within this forum and many other forums. Bottom line is HO LEDS are designed to work with a "constant current" supply. While they will work with the simple current limiting design, it is not the correct way to power them. Toymakr000 has the right idea in his reply, just the wrong parameter.

In my testing I have run more of the same Strawhat LEDS in simular housings steady on for hours at full brightness ( 100% or level 255) without fail. But I am feeding the HO LEDS with a "constant current" designed supply. HO LEDS will fail if they are overdriven by too much voltage and not enough current. If you are driving these HO LEDS directly with a standard DC power supply and current limiting, they will eventually fail, or the limiting will be so far under the full threashold of what these HO LEDS can do. There are too many variables that change between the DC current, voltage and cable lengths while PWM dimming. You can calculate the current limiting resistors till the cows come home, but the variables will always constantly change, and failures will eventually result. A constant current design takes all this out of the equation. It does not matter if the HO LEDS are 1 ft or 100ft away from the power source and it is able to adjust the current demands and voltage drops/change at the LED, reducing the chances for failures.

Even when I do a spot testing to verify a LED before soldering in or even an entire group on a board after soldering, I use a constant current bench supply to protect the LEDS.

1730_mid.jpg

Edited by mnkyboy
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Jim,

I have 21 MMFLs and have tested them with all LEDs on for hours. They are not not to the touch and I haven't had a single LED fail.

If you are using CeCe's LEDs, you are definitely running them at dangerously high current levels if yours are getting hot. You are simply frying them.

You need to get an ammeter and make sure you aren't putting more than 0.1A through any LED.

What are your resistor values and resistor wattage? What are you using for a power source? Hopefully not a wall wart.

William,

Since we are all using DC controllers (like a CMB-16D), doesn't the controller keep the current constant? You aren't suggesting a constant current source for the controller, are you?

Edited by brianfox
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William,

Since we are all using DC controllers (like a CMB-16D), doesn't the controller keep the current constant? You aren't suggesting a constant current source for the controller, are you?

Hi Brian..

Controllers such as the CMB-16D are PWM DC controllers. They are good controllers but not designed to control HO LED's. Sorry, they do NOT and cannot keep current constant at the LEDS. Most HO LED designs that are out right now tend to use current limiting resistors which will work with the HO LEDs but is not correct and failures are and have been prone to happen.

I am also not suggesting the use of a constant current power supply as a source for the controller either as it doesnt solve the problem and this type of power supply for each flood would run about $300+ each. The issue is not the power supply feeding the controller. The issue is the connection between the controller and the HO LED's and the "current limiting" concept. As I said before it will work, but it is not correct.

The power supply I showed in the previous post is what I use to test RAW HO LEDs with because it is a lab grade constant current power supply(B&K 1730) and only 3 amp. But I can connect the LEDS directly to the power supply without fear of damaging the LED by too much voltage. As soon as the LED reaches its reverse voltage, the supply automatically switches to "constant current" mode.

What I am suggesting is properly driving HO LEDS with constant current! This is a "totally" different concept from using a PWM DC board mentioned.

Edited by mnkyboy
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And constant current supplies - the internet provides your every need:

http://www.aliexpress.com/fm-store/701799/210028141/LED-Constant-current-drivers-series.html

If you are looking at DMX, also consider the _very_ nice and professionally built Lynx Aether which is about to go on co-op:

http://diylightanimation.com/index.php?board=31.0

Here is a direct comparison with the MightyMini and the Aether flood:

http://diylightanimation.com/index.php?topic=2641.msg30789#msg30789

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Hi All:

I want to thank everyone for the responses. There is a lot of food for thought. To answer an earlier question, each column of lights is running between 82 and 90 mA (calculated across the resistor). That should be well within the 100 mA limit.

I have tried something else that, seemingly, has helped a lot. I made up a new board with 2 changes. 1. I left the leads on all of the LEDs (sticking out the bottom of the board) instead of cutting them off. I thought this might help dissipate some of the extra heat by providing additional heat sink area away from the top of the board. 2. I also mounted the resistors on the under side of the board instead of the top. Again, the idea was to get the heat away from the LEDs and the top of the board and to move the heat to the rest of the enclosure so that more heat could be released through the enclosure (those resistors get very hot).

My test (with this minor redesign) seems to have been a success. The temperature on top of the LEDs went from a measured (with all LEDs on) 306 degrees to a measured 237 degrees, a 69 degree drop, with no other changes. The temperature below the board went from 120 degrees to about 130 degrees (which is what I wanted). I ran the test for several hours and had no LED failures or reduction in brightness. Of course, only time will tell if this will help the longevity of the LEDs. Tentatively, I think it will.

I am also going to try a constant current setup to find out what the effect is. We shall see.

Again. Thanks for your comments.

Jim

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My first 6 boards I also put the resistors on top... my last 3 I thought to myself.... why not put them on the underside! I was thinking heat also, so I'm glad I wasn't the only one with that thought!

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I'd' be a little nervous leaving the leads sticking out - seems like a great potential for a short circuit if something gets jostled...

I agree. Snip those leads.

And to Jim -

You mentioned that the current was "calculated". I know Ohm's law is pretty straightforward, but did you MEASURE the current? Any basic meter will let you do this.

I think just about everyone would agree - 1/2W LEDs should not be getting too hot to touch. And if you are using the recommended 1W resistors, the resistors should not even be getting warm. At < 100mA, those resistors will practically be acting as heat sinks for any surrounding parts. Something's not right...

If an infra-red thermometer was used to read the temperature, I'm wondering if the LEDs were operating an any part of the IR spectrum, producing a bogus reading.

Edited by brianfox
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  • 2 months later...

HOLY CRAP! What have I gotten myself into here? After reading most of the posts on this thread, I need to get some clarification as I just purchased my LEDs and resistors from c-leds.com.

1. Is the resitror values and LEDs correct from the package available from c-leds.com?

2. What is the consensus on controllers for the MMs?

3. Enclosure for the controller; Where and how much?

4. What power supply should I be using, and where should I get it?

5. It seems as though everyone is getting their stuff from a number of different places/suppliers. Is c-leds.com the best place to get everything, or should I have gone elsewhere?

6. With all the talk of failures of LEDs and such with the LOR DC controller, should I even be using that controller? What is my other option that is comparable in price and works with LOR?

I'm sure I have other questions, but I just can't think of them right now.

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HOLY CRAP! What have I gotten myself into here? After reading most of the posts on this thread, I need to get some clarification as I just purchased my LEDs and resistors from c-leds.com.

1. Is the resitror values and LEDs correct from the package available from c-leds.com?

2. What is the consensus on controllers for the MMs?

3. Enclosure for the controller; Where and how much?

4. What power supply should I be using, and where should I get it?

5. It seems as though everyone is getting their stuff from a number of different places/suppliers. Is c-leds.com the best place to get everything, or should I have gone elsewhere?

6. With all the talk of failures of LEDs and such with the LOR DC controller, should I even be using that controller? What is my other option that is comparable in price and works with LOR?

I'm sure I have other questions, but I just can't think of them right now.

There's been a ton of talk about the R values. CeCe sells kits with reasonable values. In my opinion, some of her R values are a little high. CeCe is also more expensive than other brands that popped up.

Enclosures...

You have a lot of choices here. You can go cheap:

Google MQF150, made by Cooper. I used to see these as low as $6.50. They are OK in my opinion, but limit where and how you can mount them.

I went with this:

http://www.acehardware.com/product/index.jsp?productId=3800144&CAWELAID=407256421

The ones I got were from Ebay but these are cool because you can clamp them wherever you need them. The housing is dark blue so it hides well.

Not to be outdone, Harbor Freight sells a dual lamp mounted on a little sled. Each light can be rotated indiviaually. It sells for about $17.

Power supplies...

You need a 24V supply. The question is - how much power? They come in 100W, 150W, 200W, etc. Assume 25W per MMFL you want to control. If you have 8 lights, you will need a 200W supply ay a bare minimum. It's always safer to buy more than you need.

Here's a link to a 350W supply:

http://cgi.ebay.com/New-24V-DC-14-6A-350W-Regulated-Switching-Power-Supply-/120589302236?pt=LH_DefaultDomain_0

modders_cn sells all sizes at a decent price. Expect to pay around $20

Housing...

You're going to need to mount your DC controller and power supply in a housing of some sort. Most people use:

http://www.yourbroadbandstore.com/product.php?pid=706098

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To Disney-fan-Reborn:

I understand your frustration with trying to gather information. I wrote a "how to" on the subject that will, hopefully, answer some of your questions. I tried to upload it with this response but it must be to big. Therefore, follow this link - http://www.wrightslights.info/resources/MightyMiniHowTo.pdf . I hope that it will answer some of your questions. For everyone on the forum, I welcome any and all constructive comments.

Jim

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  • 2 weeks later...

To Disney-fan-Reborn:

I understand your frustration with trying to gather information. I wrote a "how to" on the subject that will, hopefully, answer some of your questions. I tried to upload it with this response but it must be to big. Therefore, follow this link - http://www.wrightslights.info/resources/MightyMiniHowTo.pdf . I hope that it will answer some of your questions. For everyone on the forum, I welcome any and all constructive comments.

Jim

Jim, nice job with the tutorial. It helps even more than previous instructions. HOWEVER, as this is my first time wiring one of these things, I need to know where the DC power supply goes. I'm going to be using the LOR DMB-16D controller to run these lights. I do better with pictures, so if anyone can include some pics of their ENTIRE build of the MMs with a LOR DC controller, I would GREATLY appreciate it! Thanks in advance!

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