Halloween Forum banner

21 - 40 of 41 Posts

·
Registered
Joined
·
1,056 Posts
One more note about using an "enclosure" to assure the foam is not touching the lights - if you are mixing lights like I did (Lots of orange, some red and some purple), you can layout your strings so that you have the mix of colors you want in a single [wiffle ball / water bottle bottom / etc]. Try tying some together with twist ties or hot gluing their bases together like I did. The result, after applying the foam, will yield sort of a blurry mixture of the colors coming from a single spot. With the program controller for the lights changing the rythm and pluse, each grouping looks like a live ember pulsing in its different heat ranges. Hope this is clearly expressed.
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
Mokknoir, would you mind posting some closer macro pics of the damage? It's not clear enough to say, but it looks as if the damage isn't the LED itself, but the solder joints. You may be onto something with the guess on the foam, but it appears from the pic that it possibly melted the heat shrink and shorted at the LED leads. I'm assuming these are AC powered by a wall wart, and not by battery pack, correct?


Just an FYI for everyone, bad connections increase resistance, and heat is the byproduct. LED's of these types themselves do not get hot enough to be a fire hazard in close proximity, or directly contacting foam. Their heat output is strictly minimal, so slow down the panic.


That said, I run old incandescent strings in mine which were built just before the Halloween LED strings became common, all 3 different versions (for the last two years for one of the three *cauldron boil over*, and in the third year for the last two *hell hole & cauldron coals*) with zero problems. And, I don't cover them with whiffle balls, nor plastic bottle bottoms.


For clarification: I'm not recommending that everyone follow my path, just reporting my own results.


I strongly suspect that the reason behind this is one or possibly two scenarios, but I'd like a little more info before presenting them so we can narrow it down.
 

·
Registered
Joined
·
154 Posts
I am guessing there wasn't a whole lot of current limiting resistors invloved here.. yikes!!

I am glad that didn't happen when you were not paying attention and actually catch your house on fire.
 

·
Wild Fandango
Joined
·
1,494 Posts
Honestly, this could have happened with any product. Mishandling at the factory or at the store or by the user and you can end up with frayed wires, short circuits, etc. Or a damaged set missed (or "missed") by quality control. Granted, extremely cheap stuff off eBay is more likely to have bad solder connections and thin wires that can overheat, but it could be a freak occurrence with any light set. I still figure LEDs are much safer than using minis (or worse, C bulbs).

I used plastic to separate the bulbs from the foam when I made my hot coals, not due to any fire concerns but simply because I want to be able to replace them when needed, even if they are LEDs and far less likely to fail.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #25
Mokknoir, would you mind posting some closer macro pics of the damage? It's not clear enough to say, but it looks as if the damage isn't the LED itself, but the solder joints. You may be onto something with the guess on the foam, but it appears from the pic that it possibly melted the heat shrink and shorted at the LED leads. I'm assuming these are AC powered by a wall wart, and not by battery pack, correct?
I'll see what I can do about closer pictures, but I'm using my phone camera, so not sure about how good they will turn out. However, after looking at the damage much closer in the daylight, I agree with you. The most obvious clue is that the damage is never at the LED, but ALWAYS on the solder points. They were indeed powered by AC, no wall wart though, the electrical plug was soldered directly to the controller board. These were just a cheap Chinese version of the 8-function string lights.
 

·
Registered
Joined
·
301 Posts
Ok guys on my fire with foam I had left it on for 3 days straight and tested the heat it didnt change one bit, I agree looks like the solder points were faulty and those lights you bought sorry to say were crappy. Also I would not recommend wrapping any of those lights in plastic first theres really no point. The foam would be better directly on it to allow any small small small amount of heat to escape through the tiny air pockets or holes.
 

·
Wild Fandango
Joined
·
1,494 Posts
I don't actually leave the lights wrapped, it's just that I used a layer of cheap vinyl sheeting over the lights before I sprayed the foam. Then I peeled the plastic off the foam - I was actually surprised that it came off so easily. The biggest problem I have with LEDs is since the sets I have are not diffused, if you don't have the lights pointing straight up at the foam, they don't illuminate it. Right now I'm using two sets which creates enough light anyway. One of these days I'll either make a clip rack to hold the lights pointing up or just put a piece of mylar underneath them.
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
I'll see what I can do about closer pictures, but I'm using my phone camera, so not sure about how good they will turn out. However, after looking at the damage much closer in the daylight, I agree with you. The most obvious clue is that the damage is never at the LED, but ALWAYS on the solder points. They were indeed powered by AC, no wall wart though, the electrical plug was soldered directly to the controller board. These were just a cheap Chinese version of the 8-function string lights.

Ahh gotcha. :) Well there's a number of things in that control box that could've gone wrong. From a single out of tolerance component, to the voltage regulator going bad (if it uses one), and bypassing straight AC into the circuit. Even a mishap on the production line, and someone mistakenly putting in the control board designed for European 50hz power sources. The results could be the same from any number of different reasons. But obviously the solder joints weren't capable of handling whatever the root cause was, and hence the hot spots. ;)

Hopefully it was from an honest mistake, and not an "Idc. Just ship it" type of company. I'm really sorry that set didn't work out for you.



*snip* The biggest problem I have with LEDs is since the sets I have are not diffused, if you don't have the lights pointing straight up at the foam, they don't illuminate it. Right now I'm using two sets which creates enough light anyway. One of these days I'll either make a clip rack to hold the lights pointing up or just put a piece of mylar underneath them.

Where I'd go with that, in order to get a nice, widely dispersed light, is with 5050 or 3528 SMD LED's (if you feel comfortable soldering surface mounts). They typically have a viewable angle of 110-130°, and are perfect for such a project. Not to mention, being much cheaper than straw hats, and with no diffusion necessary due to the very wide angle, a good deal more light output is available.


If you don't feel up to the task of soldering such small components by hand, then you can also get them in adhesive backed strips. Although a little more work is necessary because the strips are flat, so you'd want to cut them to length, and solder jumpers between the adjacent strips. On the upside; no external current limiting resistors are needed, as they are already assembled on the strip. :)
 

·
Wild Fandango
Joined
·
1,494 Posts
I may use that idea for an indoor fireplace for both Halloween and Christmas, but the "grave to hell" is outside in swampy FL weather, the orange strands I have are outdoor rated and have been going for 3 seasons of rain, while I'd have to bury SMDs in epoxy or otherwise figure out some way to adequately waterproof them. Thanks!
 

·
Registered
Joined
·
60 Posts
Discussion Starter #30
Ask and ye shall receive

... sometimes.

Here's a close-up shot of an LED that had damage. This is what they all typically look like damage wise.

IMAG0333.jpg

Here's a section of the strand that is even further evidence; you might not be able to tell from the photo, but this is one continuous strand section with all but one of the LEDs damaged, exept for one. The telling part is that the undamaged LED is in the middle of the line of damaged LEDs:

IMAG0345.jpg

This is the controller:

IMAG0343.jpg

Here's the controller board:

IMAG0344.jpg


This controller doesn't look very complicated. I'd love to be able to build my own (hint, hint, <cough><cough >, tutorial request?)
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
I may use that idea for an indoor fireplace for both Halloween and Christmas, but the "grave to hell" is outside in swampy FL weather, the orange strands I have are outdoor rated and have been going for 3 seasons of rain, while I'd have to bury SMDs in epoxy or otherwise figure out some way to adequately waterproof them. Thanks!

Np! :) Well since we aren't talking about an app where you'd want a perfectly evenly spread cone of light, a coating of clear silicone caulk, or even hot glue makes a very good insulator, especially from the elements. Ofc, if you go the pre-assembled tape strip route, they do come in waterproof versions too. You'd probably want to fully pot the controller though, being outside 24/7/365 imho. :)


Ask and ye shall receive

... sometimes.

Here's a close-up shot of an LED that had damage. This is what they all typically look like damage wise.

ATTACH=CONFIG]135114[/ATTACH]

Here's a section of the strand that is even further evidence; you might not be able to tell from the photo, but this is one continuous strand section with all but one of the LEDs damaged, exept for one. The telling part is that the undamaged LED is in the middle of the line of damaged LEDs:

ATTACH=CONFIG]135115[/ATTACH]

This is the controller:

ATTACH=CONFIG]135116[/ATTACH]

Here's the controller board:

ATTACH=CONFIG]135117[/ATTACH]


This controller doesn't look very complicated. I'd love to be able to build my own (hint, hint, <cough><cough >, tutorial request?)

Confirmed, definitely over voltage, or not enough current limiting. Whether by design, or simply component failure, that's what we're seeing. That coupled with some really horrible soldering...uh, I hesitate to call that "skills" Lol! But yeah. :)

It might be possible to reverse engineer it. But you see that little tab sticking up in the center of the board between the caps, diodes, and the transistors below ? That appears to be a SIP (single inline package), and very likely that SIP contains a micro controller. Determining which, and that's the hard part, because they typically coat them w/ an opaque epoxy and or remove the markings so that reverse engineering is near to impossible.

The Chinese know an awful lot about reverse engineering, so they tend to be a little more careful about leaving visible clues. However, if there are any markings, and you can get a few higher res pics of the back (part number off the SIP, transistors, diodes, and such), I could possibly work something up for you when I have a little more time available. No promises until after 'ween though. ;) :)
 

·
Registered
Joined
·
120 Posts
Sigh, those look like exactly the strings I have for this project :(
not exactly sure how I want to proceed now.

sorry if I missed it above but did you have more than one string and did they all do the same thing?

I am going to find a safe place and plug in my strings and let them run for a few hours and see what happens
 

·
Registered
Joined
·
566 Posts
Great info on a potential problem. When I made my "HOT COALS" I ran the wire for my lights under a 2' x 3' piece of peg board then poked the lights themselves up through the peg board holes. I cut small water bottles in half and placed these over the lights then sprayed the foam over the plastic bottles and top of the peg board . I put no foam directly on either the wires or lights. Everything has been working great for a couple of years now. While I guess the LED's do generate some small amount heat it actually is very little. You can hold them in your hand and not feel any heat at all. But, if you put foam directly on the wiring and lights I bet there is no way for even a tiny amount of heat generated to dissipate and this might cause them to overheat. I am not aware of any brand of these lightweight LED light strands that are not actually made in China now. Of course, I could be wrong.
 

·
Registered
Joined
·
120 Posts
peg board might not be a bad addition, I will have to look into that.
Not having a lot of luck finding cheap wiffle balls, going to have to start drinking pop from clear plastic bottles fast
 

·
Registered
Joined
·
117 Posts
A quick mention of an alternative to spraying the foam directly onto the lights...

I set down a piece of cardboard, then put various items like cups, a small ball, etc, on the cardboard to create random lumps and bumps, then covered the whole thing in plastic wrap. I sprayed the foam onto that. This way, the stuff underneath wasn't covered in foam, and the plastic wrap will peel right off the foam. Once it was dry I spray-painted it.

It's hollow on the inside so you can then just put your LED lights etc underneath.
 

·
Registered
Joined
·
7,208 Posts
A local retired electrical engineer for a large American Co. told me how his Co. sent the specs. to a Chinese Co., they got the job, made the component, it kept failing because they did not follow those specs. and they just said, "Oh, we couldn't get that metal." End of story. ?? Wow!
The small part they made went into a much larger device used in this country.
Good enough? Says who?
 

·
Registered
Joined
·
120 Posts
Spraying the foam over plastic sounds like a good idea, once the lights are in place do you attach the foam in any way to hold it in place?
Considering the lights are not embedded in the foam and are actually well below it, did you have to do anything to point the lights up or do they come through well anyway?
 

·
Registered
Joined
·
876 Posts
Without better pictures this is just a guess, but a pretty educated one. It is possible there was some type of controller failure.
However I suspect what burned up was the resistors intended to lower the voltage for the leds rather than solder joints.
These LEDs do not draw a lot of current, they also run at a low voltage (typically 3 volts or less) so they don't generate much heat.
Lets look at a common circuit, say you want to power your led from 12Vdc power supply you have laying around (never mind directly out of the wall !).
To reduce your 12Vdc down to 3Vdc the LED needs you likely use a resistor attached to one lead of the LED.
Presto, the led gets 3Vdc, but where did the other 9Vdc go ? The resistor turned it into heat to make it go away (you can't destroy energy, only transform it).
The resistor is now trying to give off 3 times the heat coming from the LED.
How much power is heating the resistors depends on the design of the controller, and how well it's working or not.
Trivia for today.
 

·
Registered
Joined
·
117 Posts
https://www.pinterest.com/pin/370702613056510614/

Scott Garrett, this is the effect of my foam coals made using the method I mentioned. This only has a single string of red LEDs (running off two AA batteries) placed on the ground underneath - I took the photo this afternoon and couldn't find my flicker candles. :)

I haven't needed to worry about mine blowing away but you could easily weigh it down underneath if needed.
 
21 - 40 of 41 Posts
Top