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chuckd

Easiest Terminators/Snubbers to make

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I decided to make terminators for most of my channels this year (nearly 800), so I was looking for a quick way to make them. Light bulbs were out of the question, and anything involving soldering would be way too much work.

So I investigated a better option. First off, I found these plugs from Leviton. They are part number 000-48643-000, and I got them from www.acehardwareoutlet.com for 65 cents apiece.

Term1.JPG

When you pop off the cap, it looks like this:

Term2.JPG

The top view looks very nice for our application:

Term3.JPG

The 47K, 1 Watt resistors I got are the small power resistor type, and they are placed between the two screw terminals so that when you bend the leads they are in the tightening direction:

Term4.JPG

Once you bend the leads and tighten the screws down, it looks like this. Notice how the resistor sits down inside the body of the unit, tucked out of the way:

Term5.JPG

Finally, pop the cap back on, and squirt it full of silicone sealant:

Term6.JPG

That's it! No soldering or other nonsense! We cranked over 500 of these out in a couple of hours.

Hope this helps.

Chuck

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Chuck,

So once built, you just plug in the end of each strand?

Will this same resistor work for all length of strands (12', 16', 23', 34')?

Let us know how they work out.

Thanks,

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I've seen a lot of people here state that the terminators are to create a load for the triac controllers, and this helps them switch off at appropriate times. I don't really believe this, as nearly all LED strands have plenty of load to fire a triac properly. Rather, it's the capacitive effects of the LED's screwing up the normal waveform, adding extra voltage where there shouldn't be any.

Recently, I got my scope out and looked at what the AC waveform looks like when one single LED strand is connected, and UNterminated. It looks like this:

NoTermNormal.JPG

Notice how in the middle, the crossings are very rounded? This is a capacitive effect of the LED's bleeding off when the AC crosses 0 and the triac turns off. It causes an overshoot. If you add enough LED strands together, you get this huge overshoot that actually powers the LED's for a bit until the next triac turn on. So in effect, the LED's don't turn off because they're kind of powering themselves for a bit. With a single LED strand, those little humps are nearly 10 volts in amplitude. Much more than this and you'll actually light the LED's.

Then I added a terminator to the plug end of the strand. It really shouldn't matter too much which end of the strand the terminator is added to. So WITH my 47K terminator, the waveform now looks like this:

TermNormal.JPG

Nice! Now the LED's have something to bleed into (the terminator), so that voltages return to 0 when the power is off. This should eliminate the capacitive 'pops' that we see on unterminated LED lines.

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This is interesting. So without the snubbers (terminators), I could possibly see flicker at low intensities, correct? I'm not talking about the half wave flicker, but the LEDs actually flashing on and off at a low intensity. I have actually experienced this phenomenon and I am currently using snubbers that I had built last year (vampire plug version). I have found that it seems to work better when I stack the snubber on the string closest to the LOR control unit, and not at the tail end of the LED string. Another thing I have noticed is this flickering seems to happenmore with the blues and to a lesser extent, the greens, but not so much with the reds and whites. One last thing, the more LED strings I have plugged into a channel seems to cause this flicker more than if I have say a single strand plugged in (but this is not always the case; just that it seems to be the norm). Any thoughts on this Chuck? I can't say I understand the reasons behind these things (and I know I threw a lot at you here) but you seem to explain them well...

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I have found that it seems to work better when I stack the snubber on the string closest to the LOR control unit, and not at the tail end of the LED string.
This would make sense because you're not including the wire as part of the snubber.

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It definitely makes sense for it to be worse with more strings, as there would be more capacitance, which would result in higher 'bumps' (more voltage), which would result in actually lighting the LED's. With low intensities, you'd notice it more simply because there would be more opportunity to. The difference between what intensity your sequence is trying to do versus the capacitive lighting effect wouldn't be very much.

I'm going to try to take a picture of a long LED run without a snubber for comparison.

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OK, so I got motivated and tried a test with one versus 24 strings connected end-to-end (these are 50 count blue C6, CDI 2009 version). By the way, this is a Fluke 199C Scopemeter I'm using here, a great Christmas present from a few years back.

One note, I'm using an older LOR 1602 box with this. This is a V5 board with 4.3 firmware. The other scope traces are V7 with 4.4 firmware, which I arguably have been having trouble with, but that's another story. Also note that the triacs and triac controllers used in all LOR units are not 'zero-crossing', which means that they can be turned on at any part of the AC waveform.

This is all to say that these traces appear a bit different looking, but actually look more like I would expect. The V7 box seemed to produce a 'ringing' type of signal, and I can't explain that. I referred to it as overshoot previously, but it did puzzle me quite a bit. Anyway, that's off the table for the moment.

First off, this is a trace right at the channel 1 connector, with only one strand of blue lights connected, and no terminator. You can see how the capacitive effects round off the areas near the zero crossings. More on this later:

SingleNoTerm.JPG

Then I connected six strings end to end, so I could detect any trends. This again has no terminator. Notice the corners are much more rounded? We really don't get back to zero before the triac is triggered again:

6NoTerm.JPG

Next, all 24 strands connected end-to-end. Something very interesting happens here. The rounded corners have almost leveled off, leaving almost 40V on the line when the triacs are being asked to fire again. You'll notice that the upper halves of the AC waveform are full. My theory is that this is bleeding back into the 1602 controller, screwing up it's zero crossing detection. It's simply skipping the 'turn off' phase for the upper transitions. I'd bet with 48 strands end to end, these wouldn't dim at all. The visual effect here is horrible flashing between a 40% dim setting and a full wave setting.:

24NoTerm.JPG

So to see the effects of the terminator, first I placed it at the plug end of the 24 count strand, right by the LOR box. Here's the results. It seems like the 47K resistor is providing a nice resistive load for the built up capacitance to bleed into:

24TermPlug.JPG

Then I wanted to see what it looked like at the socket end of the 24 count strand (farthest from the controller). I don't see a whole lot of difference:

24TermSocket.JPG

So you can see how each additional LED strand causes this to become worse and worse, until you probably can't dim at all. With one strand of LED's, you may not need a terminator, depending on the fades you are trying to do. But if you're going to string multiples together, they seem to be a must-have.

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I am experiencing this with some of my lengthier LED strings.

Is there something that I can use in lieu of building these things? (I'm not the best at building things, but I can buy like a you know what!)

I think I read that a Glade plug in might work?

Just looking for any other type of ideas.

thanks,

Steven

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I'm not sure if anyone actually uses Glade Plug-Ins, but it sure sounds cute. Some use regular lights (C7, C9) as well, but the bulbs have to be working bulbs, and most times that is a detriment to the display.

I'd also bet a Glade Plug-In is more expensive than one of these terminators. Really, you'd be surprised how easy and quick they are to make. You can actually get the plugs at Home Depot, but you'll pay way too much for them (like $1.29 apiece or something like that). My kids built most of these for me while I was sequencing like crazy, and they're only 10, 13 and 14 years old.

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Great research, explanation and scope pictures.

Does any one see any difference in terminating the resistor inside the LOR controller right at the terminals to each channel?.....It's the same difference as plug into the power cord to each channel since we talking in parallel.

Thanks,

Richard

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I'm not sure if anyone actually uses Glade Plug-Ins, but it sure sounds cute.

:giggle::giggle::giggle::giggle::giggle::giggle:

Okay, it was funny.

Hey Chuck, would a 47K 1/2W resistor work? I've got a few of them laying around.

Also, the "attaching them to the terminal board of the controller" part? The resistors I've seen don't have long enough leads to make it to both terminals without creating extra work. But I could be wrong. Might get a little crowded in there too. Again, it's just my thoughts. But I like the idea.

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Nope, that would work just fine as well, although it'd be a bit hard to tighten down the resistor and wire together with a binding post like you see inside the LOR unit. But electrically, it should work fine.

LOR has stated that they don't build snubbers into the circuit because it caused more trouble than it solved. I've never heard any additional explanation than that, so I'm not sure what problem it actually caused.

Also, a traditional snubber circuit is more than just a resistor, so that may be what they were referring to. Again, I don't know.

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I see your point about crowded. But a little wire, soldering and heat shrink and wal laa.

Next year I am thinking about adding a terminal board inside the controller box terminating the resistors on it, then run panel wire from the output of each channel to the resistor terminal board.

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Let's do the math (just for those who don't know). The power dissipated in our resistor (watts) is given by V(squared) / R, and yes, we do use the RMS voltage of 120 volts. So we have:

120 X 120 / 47000 = roughly .31 watts

So yes, your 1/2 watt resistor will work and won't burn up. It's common engineering practice to build in a 'double what you need' protection factor, so most of us use a resistor that can dissipate at least .62 watts, and that would be a 1 watt resistor.

You resistor will run slightly hotter than a 1 watt will, but probably not too much. Let's face it, we don't usually leave the power on all the time to the LED's anyway, so I'd go for it. You can get those plugs at Home Depot if you want to do a quick test (although they'll cost too much).

Finally, I just looked inside the 1602, and you're right, those wires are too far apart to effectively tie in resistors. I imagine the common (white) side is all tied together, but it would still be hard to get a resistor from there to the far outside circuit. Plus, with 8 resistors in there, you'd be at risk of them touching each other and causing fireworks!

:giggle::giggle::giggle::giggle::giggle::giggle:

Okay, it was funny.

Hey Chuck, would a 47K 1/2W resistor work? I've got a few of them laying around.

Also, the "attaching them to the terminal board of the controller" part? The resistors I've seen don't have long enough leads to make it to both terminals without creating extra work. But I could be wrong. Might get a little crowded in there too. Again, it's just my thoughts. But I like the idea.

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To the moderators:

Just a thought but you may want to sticky this thread. The explanation here is the best I've seen. I have built snubbers and use them in my display, but never had an explanation as good as what was provided here. Just a thought.

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I havent actually tried this yet, it may be more trouble than its worth and in the end may be using the vampire plug theory. I am not into fireworks except on the 4th of July. This was just one of those light bulb moments in my brain.(ideas). So I may be speaking too quickly until I try it.

Thanks,

Richard

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