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rlilly
04-24-2008, 10:20 AM
I've got some LEDs left over from my LEDtriks effort and need some red strings. I've also got some incandscent multis that I need to convert to red.

Has anyone converted incandescent strings to LED? If so, did you add a full wave retifier when you did? What 'lessons learned' can you pass on?

I noticed Jeff converted 50 LEDs to make lawn lights in another thread.

dnesci
04-24-2008, 07:17 PM
Interesting Idea Bob. You would have to retify the string as LEDs are DC. If you give it a try keep us informed.

joneslights
04-24-2008, 07:53 PM
This site may help... I have another site to help, but it is on another computer, I'll post ASAP.
http://led.linear1.org/led.wiz

rlilly
04-24-2008, 09:00 PM
This site may help... I have another site to help, but it is on another computer, I'll post ASAP.
http://led.linear1.org/led.wiz

That's perfect! It designs the string for you!

With a full wave rectifier, you'll be getting ~60 (peak) voltage. With a 50 LED circuit, the wizard generates two 25 LED parallel strings with 270 ohm resistors on each leg.

That should work like a charm, but will mean making that 50 socket circuit into two parallel 25 socket circuits.

joneslights
04-26-2008, 02:27 PM
Here's the other site. www.ledcalc.com It doesn't do 110v though.

rlilly
04-26-2008, 04:22 PM
Here's the other site. www.ledcalc.com It doesn't do 110v though.

Yep. It has a maximum of 32 volts and 32 LEDs.

dnesci
04-27-2008, 08:44 AM
With a full wave rectifier, you'll be getting ~60 (peak) voltage. With a 50 LED circuit, the wizard generates two 25 LED parallel strings with 270 ohm resistors on each leg.


Bob, wouldn't you get 110v -1.7v or 108.3v with a full wave retifier? I'm not following your design, but I'm interested.

rlilly
04-27-2008, 09:20 AM
When you full wave rectify, you 'lop off' 1/2 of the 120 V signal, and send it in the opposite direction.

So you're getting a 60 v signal, twice as frequent.

Pictures always explain it better. Check THIS (http://en.wikipedia.org/wiki/Rectifier#Full-wave_rectification) out.

I'll be doing the 4 diode approach. I can build one for about 30c.

omzig
04-27-2008, 12:38 PM
When you full wave rectify, you 'lop off' 1/2 of the 120 V signal, and send it in the opposite direction.

So you're getting a 60 v signal, twice as frequent.

Pictures always explain it better. Check THIS (http://en.wikipedia.org/wiki/Rectifier#Full-wave_rectification) out.

I'll be doing the 4 diode approach. I can build one for about 30c.You only get half when you are using a center-tapped transformer and two diodes (conventional full-wave rectifier). If you are planning on using four diodes (bridge rectifier) without a transformer, then this is not the case.

Chaz
01-02-2009, 12:49 AM
You can "retro" incandescent strings using these LED replacement bulbs.

www.bulklights.com

Simply replace the bulb(s). No additional parts are needed. You can use both incandesent and LED on the same string too.

tonypgst
01-02-2009, 01:36 AM
120VAC RMS is 170V peak to peak in a full wave diode bridge rectifier. Minus the voltage drop of the Diodes (2.8VDC), I've always used a rounded voltage of 167VDC in my calculations when making my rectifiers for my LED strings. This assumes LEDs in series and using a voltage dropping resistor of the proper size and wattage using a calculator similar to this one, http://wolfstone.halloweenhost.com/Lighting/litlec_LEDCalc.html.

stanward
01-03-2009, 02:00 AM
120VAC RMS is 170V peak to peak in a full wave diode bridge rectifier. Minus the voltage drop of the Diodes (2.8VDC), I've always used a rounded voltage of 167VDC in my calculations when making my rectifiers for my LED strings. This assumes LEDs in series and using a voltage dropping resistor of the proper size and wattage using a calculator similar to this one, http://wolfstone.halloweenhost.com/Lighting/litlec_LEDCalc.html.

I hope you all realize that you can buy a pre-packaged bridge rectifier. There are only 4 leads to connect, where as if you purchase 4 separate diodes, you have 8 leads to connect.

tonypgst
01-03-2009, 04:39 PM
I hope you all realize that you can buy a pre-packaged bridge rectifier. There are only 4 leads to connect, where as if you purchase 4 separate diodes, you have 8 leads to connect.

Yep, but in that configuration you have the whole rectifier at one end of the string and it makes it difficult to pass through AC voltage to the female plug end. This is necessary if you want to connect more than one string in line with each other. Otherwise, using the fully package rectifiers, you must sacrifice a line so that you keep the LEDs in series between the bridge.

It is a simple process and you have flexibility in building your own rectifiers using common and cheap diodes.

ukewarrior
01-04-2009, 02:21 AM
I still have not seen a simple, complete, explanation as to how to convert a mini string to LEDs.

Is there a thread for this?

Some concrete examples would be helpful for everyone.

e.g. 50 string mini to 50 RED LEDs.
100 string mini to 100 BLUE LEDs.
Assume you want to be able to have the female end or string-to-string still work.

These two examples would cover a lot of ground since Red and Blue leds have different forward voltages. Plus, You have have the complication of 50/100 bulb counts since most if not all 100 counts are really two 50's put together.
I think this specific info would cover a lot of ground.

Has anyone ACTUALLY done this?
If yes, please show off your work!

Matt_Edwards
01-05-2009, 05:49 AM
I still have not seen a simple, complete, explanation as to how to convert a mini string to LEDs.

Is there a thread for this?

Some concrete examples would be helpful for everyone.

e.g. 50 string mini to 50 RED LEDs.
100 string mini to 100 BLUE LEDs.
Assume you want to be able to have the female end or string-to-string still work.

These two examples would cover a lot of ground since Red and Blue leds have different forward voltages. Plus, You have have the complication of 50/100 bulb counts since most if not all 100 counts are really two 50's put together.
I think this specific info would cover a lot of ground.

Has anyone ACTUALLY done this?
If yes, please show off your work!

Unfortunately, there is no one single good way to convert Minis to LEDs.
I have done 4 Blue Icicles. so I will describe how I did those.
My Icicles were connected in string of 10. at 3.4V per LED, 10 units would be 34volts. I choose 36Vdc as the supply.
adding a series resistor to each string and adjusting the value allows me to set the current in each string. I used 3mm LEDs as they fitted in the lamp housing.



Looking at 50 cct LEDs, you have two choices to make. cut the strings into smaller manageable lots or choose a DC supply that is sufficiently large enough.
The first will be determined by what Power Supplies you have to use.
The latter will require you to have 180Vdc power supply for Blue LEDS and a 120 Vdc for Red LEDs
Attached is the spread sheet I use for my LED projects.


Cheers
Matt

ukewarrior
01-05-2009, 01:08 PM
Matt,

Thanks for the info. I do understand how to drive DC powered LEDs.

I should have been more clear.

I want to change them to AC driven LEDs.
The question is:
How to do this with Simple leaded diodes as they do with the commercial LED strings.

omzig
01-05-2009, 03:21 PM
Another thing to keep in mind here is that if you're planning on using the cheap bulk LED's, they usually have a viewing angle of about 20. Unless you make sure that all of he lights are pointed directly at the viewing area or add some sort of diffuser, some of them are going to look a lot dimmer than others.

fathead45
01-08-2009, 12:51 AM
i know a guy on PC posted all the values and stuff for a 100 ct string. i wish i could find it. i know i will and once i do ill post. i will be trying to make these this summer as well.

sparky2305
05-10-2009, 06:26 PM
Hi Everyone, New to the forum and lovin` it already!
In the UK the price of LED light are stupidly high, SO... I have been making my own from scratch, Very easy to do (you just need alot of spare time)
If anyone is interested, I can post a little, how to guide with pics.
buy the way they run on 120v (not 240v uk mains)
Trev.

djulien
05-10-2009, 08:59 PM
I have been making my own from scratch, Very easy to do (you just need alot of spare time)
If anyone is interested, I can post a little, how to guide with pics.

Yes, I would like to see how you did it. I've been looking at inexpensive options for converting incandescent strings to LEDs.

don

rlilly
05-11-2009, 07:57 AM
Sure, Sparky, post what you've found. I'd be also interested.

Those incandescents usually come in 100 ct strings. It would take some major rewiring of those to make up some 25-35 count LED strings.

Last year, there were problems that some people experienced with the resistor\diode\capacitor packs on the LED strings from CDI. There was a lot of forensic exploration.

One result of that exploration for 100 ct strings is posted below. I've not yet tried it, but I plan to.

The BOM states it's for white only, but green & blue usually have the same forward voltage as white, so I'd expect it would work for those as well.

n1ist
05-11-2009, 09:55 AM
Greens ususally have a Vf of 2.1v while blue and white have a Vf of 3.6v. There's a chart at http://www.oksolar.com/led/led_color_chart.htm that shows Vf of various colors.

/mike

sparky2305
05-11-2009, 05:39 PM
Ok.....how I make my home made led lights.
Im sorry if this is a little rushed, im in the middle of packing for a two week vacation in Spain!!! I`ll upload some photos asap.

Ok. so far I have made Red, White, Blue and Green sets, yellow and uv to follow.

excluding the Red led`s the rest have a rough forward voltage of 3.2 to 3.4v
(Red 1.9 to 2.0v)

The chain is normally 38 led`s long (61 for red) and a 220r 1/2watt current limiting resistor is installed along with a 1n4004 diode
(this stops the reverse phase of AC blowing the negitive side of the set after several hours) a 1/4watt resistor can cope with the power but I wanted to over rate everything (so I can use them for many years to come....hopefully)

The overall power usage is 16 to 18 mA (about 5watts)
If I find during testing that a set is drawing over 20mA, I add an extra led or two to lower the current draw.

Word of warning regarding soldering (or soddering), Use an earthed iron
with a temp of 210'C or lower.

I blew so many leds (mainly blue) before I earthed my iron and lowed the temp from 300'C (they last for 20 or so hours then they just die out!!)

I found a supplier on eb*y who sold leds (great guy, fantastic service, he even replaced a batch of 2000 blue 5mm leds (because of the static problem)

I get each led for 2.6p!! (any color) .....our version of radio shack (maplin) sells white leds 1.20 EACH!!
Thats including shipping aswell (ordered per 1000)

If any is for looking for an led supplier, his shop is called Asia Engineer. he sells out of China. Highly Highly Recommended.


As for interconnecting the sets together, I found a shop in the net called r2hobbies.com
The name of the connector is "Tamiya Airsoft Connector Set"
these are the DC battery connectors you find on model R/C cars and stuff.
they come in packs of 10 (male and female included) for about $1.79US.

The ends are soldered to the cable and once tested the boots are filled with hot glue.
no more problems with rcd`s or efi`s tripping out, you could dump these in a bucket of water no problem. (haven`t tried that by the way!!)

I cover the ends of the leds with 1.6mm heatshrink (snug fit) and place a little bit of hot glue on the base of the led where the heatshrink dosen`t reach.

I use thin 1602 cable (not sure what that is in awg) 16 strands of 0.2mm wire.
(about the size of a cable you would find in you car on a 2 amp circuit)
the leds are spaced 15cm appart.
a hot and cold wire run the length of the set (the set is about 16ft in length)
so that 3 lots of wire.
I use brown for hot and black for cold (the bits of wire used to connect the leds together used black wire)

The wires are twisted in a drill and the final connector is installed.

it takes about 1 hour to build a complete set ( I normally build in batchs of 5 to 10)
It can be done quicker but I spend too much time watching TV when I should be working.

so far I have made over 100 sets and the cost is less than 2.10 per set.
you can probobly make them cheaper if you buy in bulk.

Hope this helps anyone looking to build there own.

anymore questions, feel free to ask.

right, got to pack.
Trev.

synnie
05-26-2009, 04:43 AM
Ive converted mini incandescants to 5mm LEDS, time consuming but when the prices of LED strings were still pretty high it was a good idea at the time.Still doing more now.Usually use 2.1V for red and orange and 3.2 for white blue green and violet...workd for me.

Goldie
05-26-2009, 06:04 PM
Ive converted mini incandescants to 5mm LEDS, time consuming but when the prices of LED strings were still pretty high it was a good idea at the time.Still doing more now.Usually use 2.1V for red and orange and 3.2 for white blue green and violet...workd for me.

Hi Synnie


Have you had any problems with the LED's rusting, ldid this last year and they all rusted at the stem, which caused the LED's to short out. ?

ukewarrior
05-26-2009, 06:36 PM
Rusting?

This should be an interesting discussion!


Hi Synnie


Have you had any problems with the LED's rusting, ldid this last year and they all rusted at the stem, which caused the LED's to short out. ?

synnie
05-27-2009, 02:22 AM
I did Goldie, havent had them short out just not getting current through.BUT WAIT!!!! theres more.Have spoken with John from Kamahilights and he has used Dow Cornings #7 release agent without any problems, also 3M Scothkote. Heres a link to the topic in another forum http://www.christmasdisplays.co.nz//index.php?option=com_smf&Itemid=63&topic=379.0 next set i do will be with these things. Dow Corning do free samples..im still waiting to see if i qualified, otherwise ill slip down to the electrical supermarket here,they have everything else at a good price.
Cheers Synnie

Goldie
05-27-2009, 08:39 PM
Synnie does that mean you have to spray the stems of the led with this stuff

synnie
05-28-2009, 03:35 AM
spray it with one i guess..i havent used any yet.looking at other products there is a #4 which is a electrical insulating , medium consistency.Looks like it may be a brush on product.Put it on the stems when inserting into the holder.Possibly use the scotchkote on the inside of the holder first

synnie
05-28-2009, 05:22 AM
Spoke to John and its a cream more like silicon or vaseline

jpb
06-04-2009, 12:27 AM
Hi Synnie


Have you had any problems with the LED's rusting, ldid this last year and they all rusted at the stem, which caused the LED's to short out. ?

I also had rust problems on the legs of my LEDs that I used to convert an incandecent string. Didn't end up with any failures though. I blamed cheap materials used to build cheap LEDs.

Jon

synnie
06-04-2009, 03:20 AM
Ive tried all my LED strings and they all work even though there is noticable corrosion inside the LED itself.Ill strip the bulbs and use some scotchkote and #7 to weatherproof them more.