switching bulbs on light strings

[ben&bobbi]

ok, i can't afford to buy crates of solid color light strings, but i got several multi colored strings last years on sale.

so i took bulbs out of 5 sets, seperated into reds, blues, yellow, etc. Then i recreated solid color strings. Unfortunately, only 1 set relit:mad:

i am assuming i have one LED is not connecting right or something. So i get to remove one at a time and see what happens! Can you remove LED's while plugged in?

Am i the only cheap one around here? anyone else have same problem?

[oldcqr]

Up front warning: I'm not an LED guru.

I don't think you can do what you did with LEDs. Unlike incans, LEDs typically draw different amounts of power for different colors. That also means that rectifiers and other parts of the LED string are sized to that draw.

It is possible that switching all those bulbs around means you have strings that are now drawing too much current (and you killed the rectifier), or that the rectifier is allowing too much current (and you killed all the bulbs).

Again: I AM NOT AN LED GURU, and I may be completely off base. However, this is the way I believe things work.

[LabRat]

LEDs (by their nature) only allow current to flow in one direction. If you have a group of LEDs in series, if one of them is plug in backwards.. it will prevent the entire series from lighting.

I suspect that this may be your issue. The problem (of course) will be finding which one(s) is/are backwards. A small lithium coin battery can be used to test each LED and allow you determine which of the two legs is + and which is -.
It's going to be time consuming...

[oldcqr]

LEDs (by their nature) only allow current to flow in one direction. If you have a group of LEDs in series, if one of them is plug in backwards.. it will prevent the entire series from lighting.

I suspect that this may be your issue. The problem (of course) will be finding which one(s) is/are backwards. A small lithium coin battery can be used to test each LED and allow you determine which of the two legs is + and which is -.
It's going to be time consuming...

This sounds more plausible than my explanation :oops:.

[dmcole]

I think that both Oldcqr and Labrat are right -- I think you have multiple problems going on.

We know for a fact that different color LEDs take different voltages -- typically, reds, yellows and oranges are 2.2 volts, while blues, greens and whites are 3 volts. LED strings are just like incandescent strings -- they are in series trying to winnow down wall power to a level that will drive the individual lamp. Those who have deconstructed LED strings have shown that in addition to rectifiers, there are usually resistors in the string.

A multicolor LED string has to balance the different voltages of all the differently colored lamps -- along with a resistor or two -- to get the combined voltage correct.

A couple of data points:

*I have had the Creative Displays catalog sitting here on my desk for the last couple of weeks, reading and re-reading (as my grandma used to call the old Sears catalog the "wish book," so is the CD catalog for me). The M-6 50-count has some interesting numbers in the "watts per string" column: blues, greens and whites are 4.8 watts per string, while red, yellow and orange are 2.4 watts per string. The multis are 2.4 watts too. So, clearly, CD's manufacturer designed the string with more reds, yellows, oranges than with blues and greens.

*I recently bought my first string of multicolored LEDs: it is a 30-count, with six each of blue, green, red, yellow and orange. So, 40 percent of the string is 3 volts, while 60 percent is 2.2 volts.*

I believe that if a DIYer wanted to build single-color LED strings from multicolor LED strings, they would have to change the resistors in some, if not all, the resulting strings. Without any changes, I think the blues and greens would be under-driven, while the reds, yellows and oranges would be over-driven.


So i get to remove one at a time and see what happens! Can you remove LED's while plugged in?


Yes, that should be fine.

\dmc

*BTW, this is not a CDI string, but yellow in a Christmas-light string? The balance -- with most of colors being in the redish hues -- looks horrible. I just noted that CDI does the same thing.

[cmitcham]

ok, i can't afford to buy crates of solid color light strings, but i got several multi colored strings last years on sale.

Am i the only cheap one around here? anyone else have same problem?

as soon as you purchased that first led, solid color or not, you officially left us cheap folk.

[ben&bobbi]

well, i guess i will try the remove and replace route first. down side is, i don't think the tree will look the same with multi color strings. they are C9 size covers on the LEDs, i could just switch them, but i am sure a blue bulb through a red cap won't stay blue!

i grabbed several when HD had the trade-in deal. they were letting me use the coupon over and over again for as much as i could open the wallet - i mean slide the card for!

[LabRat]

Yeah.. there may well be both problems going on. But you won't see the issue of the wrong voltage(s) until you have the all LED polarities all aligned.
At that point you may see DIM strings.. or blown strings.. depending on the current that is flowing.

As noted LED strings are (in theory) tuned specifically to the LEDs that are included in the string. Swapping things around could affect this.





I think that both Oldcqr and Labrat are right -- I think you have multiple problems going on.

We know for a fact that different color LEDs take different voltages -- typically, reds, yellows and oranges are 2.2 volts, while blues, greens and whites are 3 volts. LED strings are just like incandescent strings -- they are in series trying to winnow down wall power to a level that will drive the individual lamp. Those who have deconstructed LED strings have shown that in addition to rectifiers, there are usually resistors in the string.

A multicolor LED string has to balance the different voltages of all the differently colored lamps -- along with a resistor or two -- to get the combined voltage correct.

A couple of data points:

*I have had the Creative Displays catalog sitting here on my desk for the last couple of weeks, reading and re-reading (as my grandma used to call the old Sears catalog the "wish book," so is the CD catalog for me). The M-6 50-count has some interesting numbers in the "watts per string" column: blues, greens and whites are 4.8 watts per string, while red, yellow and orange are 2.4 watts per string. The multis are 2.4 watts too. So, clearly, CD's manufacturer designed the string with more reds, yellows, oranges than with blues and greens.

*I recently bought my first string of multicolored LEDs: it is a 30-count, with six each of blue, green, red, yellow and orange. So, 40 percent of the string is 3 volts, while 60 percent is 2.2 volts.*

I believe that if a DIYer wanted to build single-color LED strings from multicolor LED strings, they would have to change the resistors in some, if not all, the resulting strings. Without any changes, I think the blues and greens would be under-driven, while the reds, yellows and oranges would be over-driven.



Yes, that should be fine.

\dmc

*BTW, this is not a CDI string, but yellow in a Christmas-light string? The balance -- with most of colors being in the redish hues -- looks horrible. I just noted that CDI does the same thing.

[Mactayl]

You would probably come up with a deep purple with the color combo with the red and blue and I'm sure thats not what your looking for.

[Skunberg]

You would probably come up with a deep purple with the color combo with the red and blue and I'm sure thats not what your looking for.

Just right for Halloween ;-)

[Mactayl]

Just right for Halloween ;-)

There is always that, Halloween it's right around the corner.