Do LED Christmas Strings Go Out In Sections Like Regular Minis?

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On Monday, December 7, 2015 at 5:47:28 AM UTC-5, Ed Pawlowski wrote:

My question did not relate to "going out as string" but "going out in sections". For example, the icicles light I use are about 20' long. They are wired as five 4' sections. If you pull a bulb, that 4' section will go out. That also happens when a bulb is loose or cracked, etc. Sometimes even checking/changing all the bulbs in a section doesn't help
This weekend I combined 3 strings into 2 by cutting out sections that I couldn't get to work and soldering in good sections from the other strings. I was hoping to avoid "sectional outages" with LED strings, but I guess they are wired the same way.
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On 12/07/2015 06:44 AM, DerbyDad03 wrote:
[snip]

That's what happens wit series wiring.

I've found it usually doesn't. The problem is elsewhere, likely a poor connection.

A LED requires a low voltage (I just measured on a white one and got 2.9V). Running it on 120V would require creating a voltage drop of about 117V. This takes a big resistor that wastes a lot of power. A series of 25 of these LEDs takes 72.5V and the resistor has less voltage to drop. This design wastes a lot less power than 25 separate resistors, one for each LED.
BTW, some LED strings will use a full-wave rectifier and some don't but put different series of different polarities. If you connect it to DC only some LEDs light. Change polarity and the others come on. An electronic controller could use that for a 2-way flasher.
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Ideally, a power supply would exist that would create 2 or 3 volts DC, and each LED would be wired in parallel (individually). This power supply would have capacitors to eliminate flicker. But these mass produced light strings are made cheap, to sell cheaply, so they use the series wiring....
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As LEDs are mainly a current device instead of voltage devices they operate beter in series even if it means a real pain to find the bad one if it opens.
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On Mon, 7 Dec 2015 15:13:11 -0500, "Ralph Mowery"

If this is true, then do the LED "home bulbs" with multiple LEDs have series wiring? (meaning the ones you screw in place of a regular lightbulb on your ceiling).
I know this is not the case for battery operated LEDs. I have a 72 LED stick type flashlight, and it's very bright, (but eats batteries). For some reason, one of the LEDs burned out. The others work fine.
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I don't know how the 'home bulbs' are made. I was staying with the Christmas string types.
The flashlights have to be in parallel as they require a volt or two to light up. If they were in series it would take a lot more voltage that the batteries could put out.
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On 12/7/2015 7:44 AM, DerbyDad03 wrote:

As I stated, they go out "individual" One bulb only.
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On Monday, December 7, 2015 at 8:35:08 PM UTC-5, Ed Pawlowski wrote:

What happens if you *pull* a bulb (good or bad) out of the string?
Do any other lights go out?
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On 12/07/2015 04:47 AM, Ed Pawlowski wrote:
[snip]

Mine say that too, and sometimes that happens (I don't know how it bypasses the bad LED). Still, the most common failure is a whole series goes out.
When I put out lights, it is common to find a (50-70 LED) string where only half of it lights.
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On Monday, December 7, 2015 at 1:34:52 PM UTC-5, Mark Lloyd wrote:

"Half" would be OK, if the half were at the beginning or end of the string That's easy to work around. In my case, it's usually a section (or 2) somewhere in the middle of the string that's out. Rarely are the 2 sections contiguous.
That's what I was dealing with this weekend. I'd mark the first and last socket of a bad section, cut it out, and solder in a good section from another partially bad string in its place. I wanted to keep the strings the same length as the originals because I know how many strings I need to do my house and where I want the plugs to end up.
After I got them all repaired and hung on the house (with the one new string I needed because of the repairs) I looked up to find one 4' section that was out. It wasn't out while on the ground, and it wasn't a "step ladder reachable" section either. So, time to reposition the extension ladder and climb back up. Luckily, it only took about 10 bulbs for me to find the iffy one. I pulled the bulb, straightened the wires around the base and put it back in.
It's all good...for now.
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On 12/6/2015 11:01 PM, DerbyDad03 wrote:

path anywhere, will cause the string the not work. I just bought a string of 60 LED lamps with C9 size/shape covers. There are actually 2 series circuits, so if one LED is removed, 30 LED will go out and the other 30 will remain on. I don't know the predominant failure mode of these LEDs, however, if an LED fails as a short circuit, the other LEDs should remain on. If it fails open, where back to tracing bulb by bulb. This brings me to the most irritating problem. Running the LEDs at 60Hz produces an annoying flicker because they are on for one half cycle and off for the other. Why can't they design them with full wave rectifiers? It would only require adjusting the series resistor or whatever they use, to not over power the LEDs from lighting them on both half cycles. BTW, I have added external full wave bridges and yes they produce less flicker and yes they are brighter and yes I have not had them go bad due to over powering the LEDs.
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On 12/07/2015 07:34 AM, Art Todesco wrote:
[snip]

Some strings do have full-wave rectifiers. You could find out which by wiring a diode (1N4004) to a 120V outlet and seeing if both series still light, or only one. For testing purposes, I have 2 of these, one for each polarity.
You might TRY using a full-wave rectifier to feed the strings with 120VDC. This probably won't work because the 2 series require opposite polarity.
The series resistor will need to be a little less, since the rectifier adds a 1.4V voltage drop (two diode drops).
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On 12/7/2015 2:02 PM, Mark Lloyd wrote:

the brightness. Also, I just bought a string of 60 LED lights, which are 2 30 LED series circuits. Luckily, adding a full wave bridge externally still lights both strings. I put a cheap dimmer before the full wave bridge, and even at full, it reduces the power to almost where it was before using the bridge and makes the flickering tolerable.
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