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Howdy from Texas, yes I know its cliche but that is how we roll here in the panhandle, lol.  My name is Zach, I am married with 2 boys, one is 17yrs old and the other is 2yrs old.  I am a complete noob to chirstmas lighting. I have had a few strands of lights up for the last couple of years, and last I year added 3 inflatibles. 

 

My youngest son absolutely loves christmas lights, and I am wanting to go bigger next year.  There is a house down the block from us that has an animated light show and I have to take my son by there every night during the season.  I was thinking about building up to that some year, but before I go to big I need to evaluate my electical capabilities.  I live in an old house and I have one outlet outside that I run my lights on my house from.   

 

I just bought all new LED lights this year for really cheap thanks to the 75% off sale at Walmart, and an 180.00 inflatible for 40 bucks.  I plan on doing some DIY this year.  I love DIY projects and I have noticed that there are some good DIY projects on this site to help me along.  I may make some arches to start out with. 

 

Well that is enough for now.  I hope you guys have a wonderful new year and will be talking soon. 

 

Peace and good will to you all,

Zach.

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Hey, Zach, welcome to PC!

 

I also purchased a lot of LEDs from Walmart, Big Lots, Lowe's, etc.......

 

They all need to be "fixed" - converted from half wave to full wave.  Many can't see the half wave flicker, but long term exposure gives them headaches, makes then edgy, and a few other symptoms.  Some of us, me, inclusded, can see the flicker, especially under fluorescent lights - which to me, also have a bit of a flicker - because of phasing issues.

 

There's a simple and fairly cheap fix, although the supplier I get the parts from doubled the price of the core components, which are 1N4007 diodes. (you can use 1N4004 or 1N4406 but they have a lower PIV and are the same rpice).  100% price increase, they went from a penny each to two cents.  It takes four of them; I found my biggest cost to this mod is heat shrink.

 

PC is a great idea site, with a lot of higher-level views and suggestions.  You might want to check out http://diylightanimation.com/ for some DMX-based controllers (unfortuantely, closed source) and/or http://doityourselfchristmas.com/ for DMX, Renard, and other protocol based light controllers.  Both are DIY - you need to know how to solder.  Both sites do group buys, where the members get together and place a mass purchase of compotnents to get very good prices.  One of these will start over at http://doityourselfchristmas.com/forums/showthread.php?30928-Renard-SS-2014-Group-Buy-INTEREST-ONLY on February 1 for 8/16/24 channel Renard controllers (can run in DMX mode)  I have five of the Renard SS24 with DMX firmware as well as 5 LOR controllers; love them all, but really like the Renards 24 channels for about $100 each.

 

There are local forums, too, like http://ChristmasCarolina.com you can generally find me on, and there is The Academy that holds classes on Christmas Lighting right there in your state.

 

Do it for yourself, do it for your kids and wife.  Have fun!

 

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Welcome to PC, Zach.. You will find there are many of us Texans invading PlanetChristmas.. We are just plain everywhere huh.. I live in the DFW area and am active here on PC primarily.. If you have any questions feel free to send me a message.. Will do what i can to help.. 

 

Jack... That fix for half wave to full wave... I didn't see that one posted... can you send me a link to this project or do you have it in a step by step form? This one I am interested on. I would have bought up a ton of LED after Christmas even though they are cheaply made... if I could have gotten them to work well with LOR would have bought anyway.. 

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Welcome to PC, Zach.. You will find there are many of us Texans invading PlanetChristmas.. We are just plain everywhere huh.. I live in the DFW area and am active here on PC primarily.. If you have any questions feel free to send me a message.. Will do what i can to help.. 

 

Jack... That fix for half wave to full wave... I didn't see that one posted... can you send me a link to this project or do you have it in a step by step form? This one I am interested on. I would have bought up a ton of LED after Christmas even though they are cheaply made... if I could have gotten them to work well with LOR would have bought anyway.. 

 

Sidetrack73, basically what's happening in the cheap LED strings is the individual LED only comes on for half the AC sine wave.  All of us can see the time the LED is off, then coming back on, then going off, then back on........most of us don't realize that we are seeing that, though.  Doing a half-to-full-wave conversion means the LEDs are coming on twice as often, appear brighter (because they are on more often) and dim better.

 

There was a group buy for some small PCBs to mount the rectifier diodes on - http://doityourselfchristmas.com/forums/showthread.php?28751-Group-Buy-FWC-Full-Wave-Converter-1-2-to-Full-Wave-LED-string-Converter-board - and these will probably come available again, although the person who did the original design is trying to add the capability to add current limiting resistors to the circuit so you can reduce the number of LEDs in the string - like needing only six or so for an eye on a singing jack-o-lantern, for example, and not having to "black out" the ones you don't use.  There will be another group buy soon.

 

 

I've got this up at ChristmasCarolina.com, but I think you ahve to register as a member there, so I also have it on my own web site - http://pittsborochristmas.com/Half-wave.doc  It's basically the same as the above PCBs but without the PCB.  The PCB gives the assembly a lot more structural strength and it's less likely to have the heat shrink crack.

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JackStevens, You are very knowledge person about LEDs it seems and I have a question...  I have an inflatable that the lights went out on, after further inspection the LEDs had pulled apart from the terminals.  I initially started to reattach them but something went wrong.  I am not sure what it was but I ended up tossing the string of 3 lights.  I then got a idea that I would cut a string of 9 incandescent lights and solder them to the blower like the LEDs were. I did not notice that the inflatable used a DC adapter and it caused the lights to glow very dim but also I had to remove a light and replace it to make them light up. Well, since it didn't workout like I had planed I knixed that idea.  I bought a string of LEDs for 1 buck and decided to do the same with them as I did with the incandescent lights.  I cut down the strand about 9 lights down and wired them in series to the blower motor but I didn't get any glowing.  I don't know much about LEDs but I have researched a bunch about them and learned a lot.  I now know that my inflatable uses a 12v dc adapter, and my LEDs are rated for 3.4v per LED.  So with that info I assume I can run 3 LEDs in series and get a them to glow.  However, I can not get these lights to glow when I plug the adapter in the wall.  I made sure that I wired them up so that the polarity was correct.  Any ideas why they wont light up?

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Zach -

 

First off, get a digital volt meter (DVM) so you don't have to guess at things,  Printed and researched ratings are great guidelines, and give you a "what should be" but an actual measurement will give you a "what is"

 

Second, a quck diversionary question for you to ponder:  If you get some controllers, would you want to be able to control these lights with a controller?  If so, keep them separate.  You don't really want to try to syncronize the blower motor and lights to music, just the lights.

 

Third, keep in mind you are playing with potentially dagnerous voltages and currents.  Not so much the 12 vdc circuit, but the 120 vac /  240 vac / 170 vdc portion.  Be careful.

 

OK, what you should do before modifying the LED string is cut it someplace in the wire and do a current measurement.  You said 3.4 volts per LED; I'm going to guess they are while LEDs and probably between 12 and 20 ma (milleamps) but they may be the really bright ones at 100 ma.  The higher the current draw, the brighter they will be.  However, you can get them so bright that you'll let the magic smoke out and they'll then stay dark.  That's why a current limiting resistor.

 

You might want to check that 3.4 volts per LED by reconnecting the break in the wire you did for current measurement, and actually measure the voltage drop across one of those LEDs.

 

Measure the output of that AC adapter; you said it's a 12 vdc output.  It may or may not be a well regulated output, which means it may or may not vary a whole lot with no load, only a little load on it (LEDs only) or heavy load (motor and LEDS)  I hope it's fairly constant.

 

Now for some math.  If the LEDS are at a decent brightness at 15 ma (.015 amps) and drop 3.4 volts each, you can put up to 3 LEDs in series (as you said, you have to watch polarity)  3*3.4=10.2 volts.  4*3.4=34.6 volts.  Say your AD adapter puts out 12 volts under motor load; you can only use 3 LEDs in series, because 4 won't ligght.

 

But what do you do with those other 1.8 volts?  If you expect the LEDs to handle it, you might let that magic smoke out.  Using Ohm's law (voltage=current X resistance) and a little algebra - communitive properties, e/i=r, you get an LED resistance of 3.4/.015, or about 226 ohms.  12 volts divieded by 3 LEDs gives you 4 volts, plugging that back in you get .017 amps (17 ma) which the LEDs might handle, dumping the extra voltage as heat for a while before they get too hot and let the smoke out.

 

To keep the current flow the same as what you measured before, 15 ma, you would need to drop that 1.8 volts using a resistor.  1.8/.015=120 ohms.  So, wire the LED string something like this:

 

+12 from AD adapter +----------<+LED->---------<+LED->-----------<+LED->-------<120 ohm resistor>----------- - of AC adapter.

 

Resistor color code would be Brown-Red-Brown and use a Silver or Gold last band (10% or 5% variance tolerance)

 

Wattage rating would be "power=voltage X current" or "1.8 X .015" or .027 watts, so a 1/4 watt resistor would give you plenty of safety margin here.

 

If you decide to use 6 LEDs for increased brightness using the idea above, wire up two sets of "3 LEDS and rsisotr" - don't try to share a resistor between LEDs in parallel,  because of tolerance differences between LEDs.

 

Hope that helps.

 

-Jack

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frankly... (btw who is frank) I always wondered what those bands were for... (not an electrical genius here).. i learned something Jack.. ty.. day not wasted.. something else to go ask dad about when we meet up next month.. 

Google resistor color code; I'd copy/paste the color code here, but I can't get it to look as good as what you can find doing that.

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Thank you for all the info. It can never be an easy answer, lol. Well I just bought a multi-meter and I will be reading through the post to find what I need to do. I will probably have more questions later. Sent from my DROID RAZR using Tapatalk

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I am trying to figure out the forward drop voltage of the leds.  I had already pulled the string of lights apart before your post.  I have a 2 AA batteries that I had put together and soldered a lead from them to test my single leds, but I can not figure out the FDV.  I tried using the diode tester on my Multimeter but it says its rated for 2.8v  and I cant get the leds to light with that low of voltage.  I have tried testing the voltage across the LED but it gives me the same reading as the batteries, I think I need more volts running more lights to get an actual FVD off of the leds, am I correct?

 

My DC adapter puts 12.24 volts.

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Welcome Zach. Lots of great resources out there. Any local event you can attend is always a great place to learn and share. Check out www.lonestarholidays.com/forums to meet some locals and also look at attending The Academy this summer for a three day learning event with a couple hundred other residential decorators www.theultimateacademy.com You wont be sorry!

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Welcome Zach. Lots of great resources out there. Any local event you can attend is always a great place to learn and share. Check out www.lonestarholidays.com/forums to meet some locals and also look at attending The Academy this summer for a three day learning event with a couple hundred other residential decorators www.theultimateacademy.com You wont be sorry!

I am going to attempt to make the academy this year.. if all goes right and i get the time off.. my daughter our youngest designer/sequencer is also going to go for the same reason.. to meet others and learn learn learn... 

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I am trying to figure out the forward drop voltage of the leds.  I had already pulled the string of lights apart before your post.  I have a 2 AA batteries that I had put together and soldered a lead from them to test my single leds, but I can not figure out the FDV.  I tried using the diode tester on my Multimeter but it says its rated for 2.8v  and I cant get the leds to light with that low of voltage.  I have tried testing the voltage across the LED but it gives me the same reading as the batteries, I think I need more volts running more lights to get an actual FVD off of the leds, am I correct?

 

My DC adapter puts 12.24 volts.

 

If you don't have anything else int he circuit to drop voltage, you would be measuring the battery voltage.    That would be true of any circuit with any single component connected to a power source.  You would  need multiple devices before measuring teh voltage drop across each.  When I mentioned before aobut measuring the voltage drop, I probably should have mentioned to do that before cutting it apart - you want to get an idea of what the string manufacturer set it all to.

 

OK, Wikipedia has a voltage chart for each color; about 1/2 down - http://en.wikipedia.org/wiki/Light-emitting_diode  Keep in mind that's a guideline; your diodes may vary  a bit.

 

That chart says a white LED forard voltage is 3.5 volts, so your two AA batteries may not be providing quite enough voltage to cause the LED to fluoresce.  Suggestion:  add a potentiometer, set to maximum resistance, and a third battery.  Decrease the amount of resistance until the LED lights, set it to what you think a normal amount of lumination is being produced (may not be what you want before you let that magic smoke out!) and then measure the voltage drop across it LED.  Also measuer the current going through it.

 

OK, I'll make some suppositions here.  Your actual readings will probably vary, and you will have to plug in other values.

 

Your supply is 12.24 volts DC.  Suppose your voltage drop is 3.5 vdc (as Wikipedia says it probably is) and you are drawing a 100ma as a bright LED. 

 

3 LEDs at 3.5 volts will drop 10.5 volts, with having to drop an additonal 1.74 volts (12.24 -10.5=1.74)

 

You have two formulas you have to deal with; determining what the resistance will be to drop that 1.74 volts to operate the LEDs safely, and then calculating the wattage going through that LED so you don't under-size the resistor and burn it out.

 

The first one is R=I/E........or R=.1/1.74 (100 Ma=.1 amps, 1.74 volts)  That gives you a resistance of .05 ohms - almost a dead short.  Hmmmm.....I think I'd put a non-emitting diode in series, suche as a 1N4007 (I have a couple of hundred of those) to drop that 1.74 volts.  You don't really want a dead short there.

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Here is the information I have so far..

 

The string was 50 mini LED warm white lights.  The string is rated 4.8 watts (.04amp).  The lamps are to be replaced with 3.8v .076watt LED only.  That converts to 5.6ma per LED. 

 

I checked each of my LEDs with my 2 battery LED tester and they all glow.  What I have found now is my DC power supply is alternating volts from 8 to 11 and back again.  I think my Power Supply may be bad. My latest test was like this. " I Plugged in my power supply.  Tested the volts and got 12.24v.  Connected my string of 3 warm white LEDs at that are rated for 3.8v, and nothing happened.   I checked my voltage from the beginning of the string to the end of the string and got 12.24v. Scratched my head and asked my self "Shouldn't I have had some sort of power drop through the whole string?"  I am not sure but I think I should have. I tested again and the Volts started alternating.  I checked my outlet and was getting a steady 116v. 

 

My wife asked me  "Why don't you just through away the inflatable?"  I told her I am not excepting defeat from this thing.  So with your help I hope I can get this figured out, lol.

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FYI, I know Academy does a good job with subject matter, but depending on where you live, an alternative is Christmas Expo which is the weekend after Academy. The format, structure and execution of Expo is completely being revamped this year, and will be in Biloxi, MS. It will not be like PLUS or Expo's from years past. The website for Expo is not yet up to date, but the subject matter for 2014 will have some great topics and presenters.

 

On the electronics front, they are working on locking up Pete Peters, the PacNW's electrical guru. He is a master electrician and has taught classes in the local Union's Trade Technical School as well. Pete is a great presenter who puts everything in layman's terms. We have been spoiled to have opportunity to have him work with us for years in the NW.

 

Something to consider.

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