The temperature rise of the strips in open air is actually not too bad. Don’t drive them while still wrapped on the reel… you’ll melt the reel… don’t ask me how I know… :party:
Good idea. It is the same as to drive two strips of half length independently. Or drive the same strip from both sides.
Use two 12V power supplies with isolated secondary circuits connected in sequence to get 24V.
Are they small scraps? Can you post up pics of what you’ve got or a link to pics of the configuration of these strips?
Not extremly bad but if you glue 12V 14.4W rated LED strip to bottom side of half inch plywood and drive it by maximum allowed 1.2 A/m, the temperature rise of LED package will be about 50°C above ambient.
Your oblation saved a lot of other reels, Im sure.
BTW I’ve found site of Chinese LED factory producing both LEDs and LED strips. They have English datasheets available http://www.snowdragonledhk.com/smd-5050-flexible-led-strip-light.htm The maximum LED strip rated power they produce is 7.2 W/m. Also they have water-protected LED strips. Hope they use non-aggressive electronics-grade compound.
Number of LEDs connected in sequence and value of current-setting resistor. For 14.4W-rated 12V LED strip with three 20mA LEDs in package it is 3 LEDs in sequence and 150 Ohm resistor.
My dining room table uses LED strips to mimic Lumiline light bulbs ( Replacing Lumiline light bulbs with LEDs) Each “bulb” has 1.6 meters of strip on them driven at 1 amp. They just get pleasantly warm. I’ve never measured it because their temperature is not high enough to be anywhere near a concern. If that 1.6 meters was spread out over the length of a shelf or counter the temp rise would be quite a bit less.
I warmed up the dining room table and measured the nulb temperatures. Room was 20C, hottest point on the bulbs was 50C (middle of the bulb, middle of the strip). Coolest point was 30C at the end of the dowel, between two strips.
The bulbs have 4 strips of LEDs totaling 1.6 meters each on a wooden dowel around 18” long. There are two bulbs inside each well of the table. The wells are covered by textured glass. I suspect that the hottest point on a single 1.6 meter strip attached to wood in open air would be around 10-15C rise.
1.6 m 1A is 0.625 A/m. My 14.4W-rated power LED strip takes 1 A/m being driven by 12 V and 1.2 A/m being driven by 12.5V. I drove it by 1.2 A/m current during temperature tests. So why is my twice hotter is quite explainable.
14.4 W at 12 V must take 1.2 A/m
Note usually there are three independent LEDs in each 5050 package Usually they are used in separate sequential connections on PCB, connected to own resistors. They are connected between opposite legs of package. But there is also different kind of 5050 LEDs with only one LED crystal internally. It is connected between opposite legs also but each group of three legs is connected by metal internally.
How many resistors are on your PCB per 10 cm segment?
Nothing good I guess.
Well that depends upon if you like your magic smoke confined or free-range. J)
Phone line has low current capability. So LEDs will die without smoke once someone calls this number.
No you would connect the strips in 2S to run them off of 48V. Also, you can’t tell what voltage your phone line will actually have on it. It’s poorly regulated. Ring cycles can be 90 volts AC…
I guess you have three LED crystals in each package or 18 LEDs per section. 6 LEDs and 2 resistors are connected in sequence. I guess it is possible to cut the section routing in the middle and split each sequence into two with 3 LEDs and one resistor as on 12V strips. Also you can use use two 1.5 V AA batteries to test such LEDs. With current limiting resistor if the batteries are new.
Instead of the 2S connection or the 2P connection you could try the 4Q connection… :party:
Usually the “4Q” connection is associated with the release of vast quantities of magic smoke…
Interesting for me too. Is there some legend about “4Q connection”?
Maybe I’m reading it wrong, but here goes:
“ID10T” is a code IT professionals use for when there’s no actual problem we can fix. As a famous comedian hath sayeth, “You Can’t Fix Stupid”. I used to use the term “NAP”, as in “Not A Problem” until some high-ranked ID10Ts thought “Took a NAP” meant I was sleeping on the job. I also used “Chair-Keyboard Interface” until a co-worker, after learning my evolutionary heritage, though I was saying “Cherokee Board Interface”…
4Q is a similar code, in my (red) neck of the woods. You’ll understand when you say it out loud. Try saying this angrily someplace where no one gentile can hear:
“What did you say to me? Ah 4Q!! I’m leaving!”
Maybe codes aren’t the best form of communication….
Dim
Based on my initial testing, you would guess correctly.
Or you can use 2, 1.2v rechargeables to prove the 3-crystals guess!
And if you (or I) cut one off the strip & solder 2 bits of Cat6 in buss fashion across all 3 leads on each side, you can use an 18650 to make the 3 crystals shine quite brightly!! They do get hot, but it’s not like you can hold the other ends of the Cat6 wire to the 18650 ends for very long anyway. It’s no XM-L, but I can surely see where scrounging a handful of these & mounting them on some useful substrate will indeed be worth the effort. Especially since these particular 5050s make a fairly lovely shade of “white”…
Oh, thank you! I didn’t read this in English textbooks… :bigsmile:
Usually it is not a good idea to connect a few LEDs in parallel without separate current-setting resistors. And don’t forget if you overdrive your LEDs they will shine brightly but not long.