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Thread: How to turn half wave LEDs to full wave LEDs

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    The Christmas Nutt walter's Avatar
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    Default How to turn half wave LEDs to full wave LEDs

    Hey guys,

    I picked up a few LED stings from Lowe's today. Know they half wave how could I turn them in to full wave? I know Jack did a talk during the convention but I missed it due to all the cooking I to do. If y'all could help me out it would be great.

    Thanks,

    Walter
    Walter


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    Havin fun ! kidcole's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Here's a copy of Jack's tutorial. Works fantastic. I have been twisting up diodes for the last month .. If you want some diodes, swing buy the house today. I am home all day <sequencing> .. :-)
    Attached Files Attached Files
    Thanks,

    Denny Cole
    https://www.facebook.com/groups/Cole...ristmasLights/

    Back to Work <unretired> so I went Static in 2017. Planning xLights when I retire <again>. Maybe 2019 ?

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    Blowmold Elite Brad Caudill's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    I got my LED's from Walmart and I honestly haven't seen the flickering. I doubt they are full wave.

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    This space for rent. Al in Raleigh's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Brad it only effects certain people but the people that it does effect get sick extremely fast. I am told that anyone can see the flicker if they take off their clothes, rub Crisco over their entire body, and stand out in the yard looking directly at the lights while singing Achy Breaky Heart at the top of their lungs. I didn't have to do the testing because the half-waves make me sick, and I am thankful because just the Achy Breaky Heart part would make me sick.
    Al

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    Blowmold Elite Brad Caudill's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    oh ok.. I will try that tonight to see if mine are half-wave.

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    wrench twister TGabriel's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Is that Crisco in the bottle or in the can?

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    The Christmas Nutt walter's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    The can works the best.
    Walter


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    Professional Net Lurker Jack Stevens's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    If they don't say full wave or flicker free, they are half wave. "Half wave" is a negative so they won't put that on the box. "Flicker free" may be done with capacitors, which don't handle dimming well, unless you like small explosions.

    It costs the manufacturer a bit more to do full wave. As near as I can tell, it would be probably about 10 cents more to do it......so they're going to trump why that string costs more than the half wave string.

    Denny - that adapter I gave you for your Big Lots LED snowflakes - I used one of those on my Big Lots Icy Icicle spear icicle lights. Works well, and a single adapter is running about 8 sets. It really brightens them up, too, since they're getting voltage twice during the AC sine wave instead of only once. We ended up buying a lot more LED strings at Big Lots at their 1/2 price before-Christmas sale this past weekend.

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    Havin fun ! kidcole's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Quote Originally Posted by Jack Stevens View Post
    If they don't say full wave or flicker free, they are half wave. "Half wave" is a negative so they won't put that on the box. "Flicker free" may be done with capacitors, which don't handle dimming well, unless you like small explosions.

    Denny - that adapter I gave you for your Big Lots LED snowflakes - I used one of those on my Big Lots Icy Icicle spear icicle lights. Works well, and a single adapter is running about 8 sets. It really brightens them up, too, since they're getting voltage twice during the AC sine wave instead of only once. We ended up buying a lot more LED strings at Big Lots at their 1/2 price before-Christmas sale this past weekend.
    Hi jack .. I forgot to get back with you about the diodes. THANKS ! I've soldered the rectifiers directly to my light strings and they look great. I've made about a dozen of them so far .. with about 15 to go ! They are clearly brighter and smoother looking ! I am using your adapter cable on those snowflakes and have three strings running on one.

    <for the group> You only need one rectifier when you put multiple stings on the same channel, but you do have to check the polarity of each successive string after the first one, to make sure you have the plug in the right direction. I put a tag on the plug end of all my strings where I added a rectifier. It says "RECTIFIED" .. to remind me that the other end of the string is DC (not AC). You don't want to melt your incandescent strings by plugging them to a DC line !
    Thanks,

    Denny Cole
    https://www.facebook.com/groups/Cole...ristmasLights/

    Back to Work <unretired> so I went Static in 2017. Planning xLights when I retire <again>. Maybe 2019 ?

    Falcon - 3 F16V3 & 1 PiCap, Sandevices - 2 E681 & 4 E6804, 288 Channels Lynx Express, 108 Channels DC DMX,
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    Professional Net Lurker Jack Stevens's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Quote Originally Posted by kidcole View Post
    Hi jack .. I forgot to get back with you about the diodes. THANKS ! I've soldered the rectifiers directly to my light strings and they look great. I've made about a dozen of them so far .. with about 15 to go ! They are clearly brighter and smoother looking ! I am using your adapter cable on those snowflakes and have three strings running on one.
    Good to hear that. I think technically they aren't brighter, it just appears that way since they are on twice as much per second.

    Quote Originally Posted by kidcole View Post
    <for the group> You only need one rectifier when you put multiple stings on the same channel, but you do have to check the polarity of each successive string after the first one, to make sure you have the plug in the right direction. I put a tag on the plug end of all my strings where I added a rectifier. It says "RECTIFIED" .. to remind me that the other end of the string is DC (not AC). You don't want to melt your incandescent strings by plugging them to a DC line !
    That is one set of 4 rectifier diodes, unless you buy bridge rectifiers, which are already 4 diodes inside one common package. But then, you probably won't find those for 2 cents per diode (including shipping)

    And you won't melt your incandescent strings plugging them into DC. The voltage isn't changing, just the waveform. At 1 amp (typically) per diode, though, you might burn the rectifier array out.

    You may see,, however, if you are into such things, more metal fatigue on one side of the incandescent light filament. It's getting hit with the same polarity voltage all the time and the negative side of the filament will have slightly higher voltage than the positive side, because of the resistive voltage drop, causing a higher temperature on that side of the filament. Personally, I don't care about that. I wouldn't have the equipment necessary to measure such things if I did care.

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    This space for rent. Al in Raleigh's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Jack, I might have missed something but the output of a full-wave rectifier is twice the voltage of a half-wave. I thought originally you used a dropping resistor to compensate for the added voltage. I said all of this without researching what you originally did, I am short on time this morning.
    Al

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    Professional Net Lurker Jack Stevens's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Quote Originally Posted by Al in Raleigh View Post
    Jack, I might have missed something but the output of a full-wave rectifier is twice the voltage of a half-wave. I thought originally you used a dropping resistor to compensate for the added voltage. I said all of this without researching what you originally did, I am short on time this morning.
    Al
    Al -

    Not so. Line voltage (110 VAC RMS) is about 170 volts to peak positive, then 170 volts to peak negative, back to positive, negative, etc. Hence, the name "Alternating Current"

    Yeah, I know you know that, but this is a public forum, and I'm explaining my thought processes on this.

    Using the half-wave LED string with the manufacturer supplied current limiting resistor means only the positive peak of that sine way will get through (OK, I know, it could be the negative peak only) Since the other half of the cycle is blocked by the normal LED's diode action, the LED is dark during that half cycle, causing the flicker many of us can notice.

    The harder part comes into play when the string manufacturer actually has two strings on one plug, and connects the second string in reverse polarity to the first. That works on AC; for the first half cycle, the first part of the combined string is on, and on the other half cycle, the other part of the combined string is on. I think your eyes catch that even more so than the strings that aren't that way.

    On those strings, you have to cut and re-splice the half strings so they are both the same polarity.

    I'm thinking this would be a good topic/mini-workshop for the first TASL meeting. I have plenty of spare diodes; I bought 1,000 of them and have only used a few hundred. I'm thinking that if everyone brought a short extension cord we could convert them into AC-to-DC adapters to play with LED strings with (bring those, too; you'll see the difference)



    Putting the bridge rectifier puts both of those 170 V peaks on the same side of the reference line of zero volts. The LEDs see forward voltage for both peaks, only turning off during the zero-cross time of the AC wave. The current limiting resistor isn't dropping any more voltage; it's dropping the same voltage twice as often. This may present a problem only if the manufacturer counted on the half cycle that the LEDs were dark to let the resistor cool. I haven't seen this to be a problem, though.

    A 2-diode full wave rectifier can double voltage. A bridge rectifier won't, and removes the duty of rectifying the AC to DC from the LED's. That part was obvious to me, but Denny thought the plastic bulge in the wire that holds the resistor (and I hope NO capacitor) was also the 1/2 wave rectifier, not realizing that the LEDs were doing that function until I pointed it out. I assume others make that same incorrect assumption, but I may be incorrect in that assumption.

    I'm thinking this may be a good discussion topic/mini-workshop for the first TASL meeting. I bought 1,000 diodes and have only used a couple of hundred. If people brought short extension cords or vanpire plugs we could make up some adapters so people could see the idfference in their LED strings (bring some of those as well.)

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    This space for rent. Al in Raleigh's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Jack, you are correct about full-wave rectifiers as long as no smoothing capacitors are involved which messes with the average current. I forgot the strings don't have caps. I immediately thought of Denny's Martha Stewart lights which have caps.

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    Space rented from Al SWood's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Quote Originally Posted by Al in Raleigh View Post
    Jack, you are correct about full-wave rectifiers as long as no smoothing capacitors are involved which messes with the average current. I forgot the strings don't have caps. I immediately thought of Denny's Martha Stewart lights which have caps.
    Speaking of, and not to hijack, I've had a set of marthas plugged in for a couple of weeks now and they seem to be doing fine so far.
    Shannon Wood
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    Havin fun ! kidcole's Avatar
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    Default Re: How to turn half wave LEDs to full wave LEDs

    Quote Originally Posted by SWood View Post
    Speaking of, and not to hijack, I've had a set of marthas plugged in for a couple of weeks now and they seem to be doing fine so far.
    I appreciate the update Shannon. The Martha lights support desk called me back and their engineers said we would have no trouble dimming them. Al and I drew up the circuit and did some calculating and the Cap is only active for milliseconds. We're really not sure why they bothered. Their circuit adds diodes at each end of the string, so they are rectifying each half separately. This is probably for safety certification reasons.

    I still like Martha <I always did - even before she made FWR LEDs... > !
    Thanks,

    Denny Cole
    https://www.facebook.com/groups/Cole...ristmasLights/

    Back to Work <unretired> so I went Static in 2017. Planning xLights when I retire <again>. Maybe 2019 ?

    Falcon - 3 F16V3 & 1 PiCap, Sandevices - 2 E681 & 4 E6804, 288 Channels Lynx Express, 108 Channels DC DMX,
    10' Pixel MegaTree, CoroFlakes w/Pixel Modules, Pixel RBLs, 2 Pixel Matrix 16x25, 10" RGB Ornaments, 7x230 Pixel Icicle Matrix,
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    Likes SWood liked this post

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