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weirdjimmy
12-11-2009, 11:36 PM
OK this might not work. I don't know. But here it goes. Could you buy LED's in bulk and replace the incandescent bulbs in your old strings? It seems to me this would be "GREEN" and save you some green. Just a thought.

Merry Christmas everybody

BF210
12-13-2009, 01:30 AM
Nice thought but won't work. LEDs act very different electrically. The LEDs need a rectifier and some protection circuitry to keep current spikes from turning them into dark emitting diodes (DEDs.) This is typically a small cylinder or lump in the LED string at one or more places.

Save yourself time/frustration/money by purchasing LED strings designed for holiday lighting from the after Christmas or early season sales from the vendors mentioned elsewhere on these forums.
(yet another Don)

dirknerkle
12-13-2009, 11:08 PM
The LEDs need a rectifier and some protection circuitry to keep current spikes from turning them into dark emitting diodes (DEDs.) This is typically a small cylinder or lump in the LED string at one or more places.
(yet another Don)

DEDs?

LOL!!!!!

raethebj
12-27-2009, 02:38 AM
WRONG they don't NEED a rectifier a led is a diode in itself...light emitting diode...... they work fine with ac except they pulse slightly from the 120 ON OFF cycles a second (60 HZ)

Some sets have the rectifiers to eliminate the pulsing...others do not

if u can calculate the voltage correctly and can get the leds to fit by all means do it


one thing tho every led needs to in series the same way..one side of an led is flat at the bottom this is its negitive side.....so you need positive to negative with every bulb

ErnieHorning
12-27-2009, 03:10 AM
You could replace all the lights with LED's. You'd need to add a diode and a resistor. You would also need to water proof all of the LED's. It's a lot of work for maybe not so great of a result.
WRONG they don't NEED a rectifier a led is a diode in itself...light emitting diode...... I doubt that any LED will take a reverse voltage of 170, at least not for long, so a diode that blocks is needed.

jpb
12-28-2009, 11:14 PM
I have done this with 2 low voltage 150 light strings and while it was a success I won't do it again.
I used a small rectifier package at the start of the string and then cut and soldered and insulated each section of the string to get to down to the correct number of bulbs and added a resistor to limit the current.
It was a major effort to get a couple of strings that I needed in Red and Green for my mini trees.

Jon

mrpackethead
12-28-2009, 11:27 PM
You could replace all the lights with LED's. You'd need to add a diode and a resistor. You would also need to water proof all of the LED's. It's a lot of work for maybe not so great of a result.I doubt that any LED will take a reverse voltage of 170, at least not for long, so a diode that blocks is needed.

The reverse voltage however is spread out over 'x' LEDS.. ( if you ware using Blues, say 50 on a 110VAC line ), so you are only talking about 3.5V per led.. that level they can handle.

personally, i'd say do it nicely, use DC.

ErnieHorning
12-29-2009, 12:10 AM
Note that just adding two diodes in series does not make a diode capable of blocking twice the voltage. Their leakages may be significantly different and the low leakage diode will see most of the voltage.

dirknerkle
12-29-2009, 01:31 AM
I have yet to start dabbling in the led string arena, and I'm wondering whether it's feasible to run the LEDs in parallel with straight DC instead of in series? Or are any strings actually designed/manufactured this way at all? I'm thinking that a string of 100 LEDS each drawing 20ma would only be a couple amps of total draw on the line.

Or am I so far off base that it's a completely ridiculous concept?

David_AVD
12-29-2009, 01:55 AM
Whilst you can run LEDs in parallel, they may not share the current well if there's too much resistance in the wiring. The ones closest to the power source may hog more current (and be brighter) than the ones further away.

A Marchini
12-29-2009, 07:34 AM
You could replace all the lights with LED's. You'd need to add a diode and a resistor. You would also need to water proof all of the LED's. It's a lot of work for maybe not so great of a result.I doubt that any LED will take a reverse voltage of 170, at least not for long, so a diode that blocks is needed.

Ya know , I thought that very thing, but then I have seen normal LEDs used in power strip applications with nothing more than a large resistor to cut current in the forward BIAS case. I figured these things would cut out in a day or so , but I know for a fact that we didn't have a large failure rate.

Tony M.

aussiephil
12-29-2009, 09:51 AM
As has already been stated LED's are in themselves diodes (light emitting DIODE), no additional diodes need to be actually added.

Resistors will need to be calculated to limit forward current to 20mA

most standard LED's have a reverse bias voltage rating of 5v and this is a major factor in calculating the minimum number of LED's that can be used in a AC string.
The maximum is calculated by the forward voltage drop that varies by colour.

So lets run some numbers

110v AC has a peak 155v
121v AC has a peak of 171v, this is just 10% higher than 110v and is no doubt seen on the US grid at times.

171 / 5 = 34.2 rounded up = 35 LEDs Minimum quantity to a string to cover the peak voltage on the opposite half of the AC wave.

Strangely the same as a 35 count Blue string you can buy in the US.

All LED strings are half wave rectified by default, the Full Wave strings have a diode bridge arrangement that ensures both half cycles power the leds.......

Full wave strings begin to act more like DC powered strings and all calcs should be based on peak AC voltages.

Back to the original question..
Yes you can, but I would not consider it worth the effort, even in OZ paying $20 for 120 count strings gives a per LED cost of 16cents, even buying Bulk leds at 5c it's just not worth my time.

aussiephil

dirknerkle
12-29-2009, 01:31 PM
Back to the original question..
Yes you can, but I would not consider it worth the effort, even in OZ paying $20 for 120 count strings gives a per LED cost of 16cents, even buying Bulk leds at 5c it's just not worth my time.

aussiephil

So if I'm understanding this right, making your own LED string is really only something you'd want to attempt if you needed it to be a specific custom length for a specific reason (ex: a string with 53, 86, 114 leds, etc.) to cover a specific space evenly. I see no other advantage for building one's own LED strings.

And from the sound of it, the cost/led is what will essentially drive the cost of the retail strings. Even if the cost got down to .05 per LED, we're still looking at a per string cost that's more than double an incandescent string of a like number of lights.

The bottom line for me is that it still looks like LEDs are more of a luxury than a necessity at this time. The power usage differential for an individual homeowner doesn't appear to be that great; even if saves $100/year in electricity, that's not a lot of money and I'd see that as a negligible benefit. This is not to say the collectively, the decreased power usage should every DIYC-er changeover to LEDs would be insignificant; cumulatively it could certainly prove to be a very ecological thing to do.

In my opinion the most useful benefit to the individual homeowner is derived in the total number of lights one can use per electrical circuit, which opens the door for not only more, but more exotic displays without having to add additional power subpanels to the house. For the DIYC-er who feels that he/she is already using the maximum current available in their home yet wants to add more lights, that appears to me to be the logical justification for purchasing them.

One issue I'm struggling with is LED color. Many of those I've seen seem almost unnatural in color and just don't look as "warm." To me, the ambience of a display is as important as the scope. It's why candlelight at the dinner table looks the way it does and why lighting the dining room table with an LED flashlight just doesn't cut it... Hmmm... looks like I've got a few things to get over before I make the switch...

fathead45
12-29-2009, 02:18 PM
well i tried last year and i had 50 leds converted in about 30mins. that included putting hot glue in each socket to seal it. didnt work b/c i had too many leds, but im going to try to revisit it. i have plenty of time to play with it.

dirknerkle
12-29-2009, 02:23 PM
well i tried last year and i had 50 leds converted in about 30mins. that included putting hot glue in each socket to seal it. didnt work b/c i had too many leds, but im going to try to revisit it. i have plenty of time to play with it.

Hmmm... 20,000 converted to LEDs would be only... ummmm... 200 hours....

My eyes are crossed already thinking about that.... arghhhhh :roll:

fathead45
12-29-2009, 02:44 PM
lol that would be alot. i might start this year with my river of blue and slowly do my whole setup if all goes well. only 7k to complete those, lol

Warlock
01-09-2010, 03:34 PM
So has anyone done this with success ???? If so can you please provide a step by step so we all can learn this idea and have success..Also to can you provide the calculations for the resistor values etc that would make this owrk with dc and or 120 volt ac..
Greatly appreciated.
Joe..

synnie
02-14-2010, 03:26 AM
I have 4000 LEDs now which i have converted from Incandescants, and after the first 50 being trial and error to get it right the rest breezed through in no time.Difference is mine run low voltage DC (24-48 depending on strings). Running through Olsen 595's with REN-C's without SSR's.I mentioned doing these quite a while ago but other than John who lives over the pond in the Land of the Long White Cloud noone else seemed to give a stuff....