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Southern Man
09-15-2008, 07:54 AM
I'm redoing a kitchen and want to use LED lighting under the cabinets for energy efficiency and heat reduction, and I found two types.

1. Bluish color lights.
2. High intensity type, Available at Slowes for $50 as three pucks (1 watt each) strung together with a 34V transformer.

Type 1 is too dim for me so I'm looking at type 2, and temporarily installed a set to see how the wife likes them, and she does. Some issues with these:

1. Is the 34V still considered low voltage?
2. The units create a problem with my AM radio.
3. The pucks get pretty hot so I'm not sure how energy efficient they actually are. The package doesn't say how many watts the units actually use. the transformer is labeled output: 350mamps constant current 35VDC.

jadnashua
09-15-2008, 10:02 AM
Power=current*voltage
12.25=0.35*35

They make 20W soldering irons. Now, depending on what you are soldering, it might take awhile to heat up the joint. One used for plumbing would need to be significantly larger...still a small one can start a fire.

Southern Man
09-15-2008, 06:16 PM
Power=current*voltage
12.25=0.35*35

They make 20W soldering irons. Now, depending on what you are soldering, it might take awhile to heat up the joint. One used for plumbing would need to be significantly larger...still a small one can start a fire.

OK that's the maximum output of the transformer- thanks and duh! for me. There is another note on the label that it will run up to 8 pucks, so the wattage for three is only 3/8*0.35*35 = 4.6 watts. It beats the alternatives.

edlentz
09-15-2008, 08:11 PM
I was considering the hockey pucks until I found a 20" LED strip that directly plugs into 110vac. They give lots of light and were about $20 per light. Got them at *******.

Southern Man
09-16-2008, 11:17 AM
I was considering the hockey pucks until I found a 20" LED strip that directly plugs into 110vac. They give lots of light and were about $20 per light. Got them at *******. What color is the light? The only ones that I saw like that were the bluish, lots of LEDs, but fairly dim. And I searched the Big 3 plus on the web.

edlentz
09-16-2008, 11:23 AM
The light is a bright white. I forget the name of them. I'm at the office now but when I get home tonight I will get you the name and the site where you can get an idea what they look like

Ed

Southern Man
09-16-2008, 11:28 AM
The light is a bright white. I forget the name of them. I'm at the office now but when I get home tonight I will get you the name and the site where you can get an idea what they look like

Ed Let me know if they affect your am radio reception. I have to turn mine off when I listen to Rush. :(

edlentz
09-16-2008, 06:22 PM
Here's what I have:
http://zilotek.com/led_striplight.htm

I don't know if they affect am radio, I don't listen to Rush.

Good Luck

Southern Man
09-16-2008, 06:28 PM
Here's what I have:
http://zilotek.com/led_striplight.htm

I don't know if they affect am radio, I don't listen to Rush.

Good Luck Where did you buy them?

edlentz
09-16-2008, 06:38 PM
I got them at ******* . It is a big box like HD or Lowes. At least around here. It is kinda puzzling that that website talks about providing the cuatomer with the best but there isn't even a list of places to buy them. It looks like ******* is in the Midwest. Interesting the company name gets blanked out when I post. Here is their website http://www.m e n a r d s.com/storeLocator.do

Southern Man
09-16-2008, 06:51 PM
Thanks there's none near me and they don't list it on line but I'll call them to see if I can order. I googled the manufacturer and came up with zero. I've been looking for a decent LED for weeks now.

edlentz
09-16-2008, 07:22 PM
No problem. If you can't get them maybe we can work something out. Good Luck

hj
09-17-2008, 08:32 AM
If you were in Lowes site, and you wanted to tell someone where to get an item, do you think Lowes would let you tell them that Home Depot is the place to get them? I am sure they would also block out references to competitors.

edlentz
09-17-2008, 09:52 AM
HI HJ

I get your point and I agree. What I was referring to was when I typed in M e n a r d s in the messafe I was posting here when I saved it all that showed up was *******. When you typed Lowes and Home Depot that didn't happen. I thought that might be a way for the system here to keep people from using store names.

Southern Man
09-17-2008, 11:41 AM
HI HJ

I get your point and I agree. What I was referring to was when I typed in M e n a r d s in the messafe I was posting here when I saved it all that showed up was *******. When you typed Lowes and Home Depot that didn't happen. I thought that might be a way for the system here to keep people from using store names.
They don't sell them on line. Could you do me a favor, if you have an am radio, turn it on next to your light and see if it affects the radio reception? Before I call them and try and convince someone to take six off a shelf and mail them to me I need to know if I'm going to run into the same problem.

edlentz
09-17-2008, 11:56 AM
Sure,
Let you know later tonight

edlentz
09-18-2008, 05:35 PM
Sorry I didn't post last night. I fired up the old AM radio and literally put the LED strip on it. Besides the normal hiss of AM it was quiet as a church. I did heap a pop when I first turned on the light. I tuned through the band and was quiet all the way through. So probably, will work out for ya then.

alternety
09-19-2008, 12:47 AM
I suspect that long of a string is using the full 120V and has no electronics to change things (except maybe a diode). There is no active electronics and they should never cause radio interference.

The lights with fewer LEDs require the voltage to be reduced. If there is a transformer, this can be a simple diode pair and should not cause interference.

The third case is the one that can cause interference. This unit will have an active switching power supply to generate the appropriate voltage. The switcher can radiate. If the "transformer" in case 2 is real small and very light, it may actually be a switching power supply. New energy regs are making these more common.

edlentz
09-19-2008, 03:51 AM
This strip plugs directly into 120vac. No xfrmr at all

jadnashua
09-19-2008, 07:33 AM
LED's only run on a couple of volts, so unless you string them in series, you need some sort of supply or regulator. If you have enough lights, the drop across each can be low enough to avoid extra electronics, but then if one dies, the whole thing may go out...in the same idea as older Christmas tree light strings. If the power requirement isn't high, a switching power supply transformer can be quite small, so it could have one and you'd never know it.

edlentz
09-19-2008, 07:40 AM
Both of you are right. I have goofed around with LEDs since they first come out. They only need about 3.3 volts and a miniscule current. The strip I have is about 20 inches long with the LEDs and a dropping resistor visible under an epoxy. The strip itself is about 1/4" thick by about 1/2" wide. So the electronics is very small. Given the life of LEDs if they last 10 years I will be happy. The only thing I can think that might take them out is a power surge. But for around $17 a 20 light strip they are WAY cheaper that anything else I can find around here.

Southern Man
09-23-2008, 06:15 PM
Sorry I didn't post last night. I fired up the old AM radio and literally put the LED strip on it. Besides the normal hiss of AM it was quiet as a church. I did heap a pop when I first turned on the light. I tuned through the band and was quiet all the way through. So probably, will work out for ya then.
Thanks. I just sent them an an email to see if they'd mail me some.

edlentz
09-23-2008, 06:22 PM
good luck. With any luck I will be installing mine in a day or so.

alternety
09-24-2008, 02:30 PM
LEDs ain't LEDs. Some of the posts have sort of assumed that LED A is the same as LED B. Not so.

The forward voltage drop is a function of a number of semiconductor things. It tends to vary as the type of diode and material. There are a fair number of combinations.

Before you try to play with diodes, check the manufacturers specs for voltage drop, current, and power dissipation. The tricky part about LEDs is the dissipation of heat. If you get into real power (maybe about 1W) you need to understand power dissipation and heat sinks. Note that white LEDs tend to have higher forward voltage drops than others. They are really an ultraviolet diode with a frequency translating phosphor. Like a fluorescent lamp.

The strings that use 120VAC simply have the number of diodes for their forward voltage drop to match the line voltage. There is probably a diode to eliminate reverse biasing of the LEDs. The reverse voltage tends to be fairly low.

If you want to roll your own, you have to be able to calculate the power supply voltage and some sort of current limiting mechanism to provide the required diode current.

The last time I looked it is easy to find diodes of up to 5W. With 1W being much cheaper. You can build your own lighting strings. You must know enough to control forward diode current with your power supply. You can research how to do this online.

I don't know what wattage the available diode strings provide, but I would guess well under a watt per device. Play with it. You can do better. Check out candlepower.com.

I am going to use LEDs for emergency lighting and under-cabinet. I have a whole bunch of old 1W units. Current devices are much better in $/W. The diodes themselves are mostly a bit under fluorescents in light efficiency. Newer ones may be better by a bit.

Play around with some. But be aware that if you do not understand what you are doing you may release more magic smoke that is financially advisable.

Thatguy
09-24-2008, 05:29 PM
Is the 34V still considered low voltage?

My '99 copy of the NEC seems to say that above 30 vrms or 42 vac peak or 60 vdc is not low.
I can't imagine a safety hazard with this, though.

One watt into an LED = 4w or 5 w into an incandescent.

edlentz
09-24-2008, 05:35 PM
What does the NEC say about 48vdc? How about 90-135 @ 20-30 hertz? That is typically what a telephone line consists of, and I believe that is considered low voltage.

Thatguy
09-25-2008, 09:00 AM
How about 90-135 @ 20-30 hertz? That's during ringing. Otherwise it's ~50 vdc (4 ea. 12v batteries in series being charged).

What does the NEC say about 48vdc?
I couldn't figure it out, and my code interpretive book by Mr. Mullin just said, Be careful around phone lines. Mike Holt's Forum is a good place to ask.

The phone line can't deliver all that much energy, and it's the current vs. time that harms.
GFIs trip according to
Time in seconds = (20/[current in mA])^1.43
and this is the U.L. maximum. Most GFIs work quicker than this.

In the whole history of the U.S. Navy, only one person died from a voltage as low as 47v.

I'd be interested to find out if anyone was ever killed by a U.S. phone line. Good luck in getting a straight answer about this one.
I guess pasting the line

"v. Bell Telephone" wrongful death shock

into the Google search box is a good place to start.:p

edlentz
09-25-2008, 09:41 AM
Well,

IMHO most of this conversation is moot anyway. If one spends the time to find, figure out the connections, voltages, etc..., and then putting it all together that is fine. For one I got my LED cabinet lights for a really good price (I am sure far less that if I spent the time to make them). I can install them easily and go on to other things. 30 years ago I might have made my own if the technology had been there, but not today. I have other things to do.

edlentz
10-06-2008, 08:27 PM
Hey Southerman,

How'd you make out?

Ed

Southern Man
10-07-2008, 07:25 AM
Hey Southerman,

How'd you make out?

Ed

The line voltage became an issue. I have three wall outlets for these and my wife wants to light up 5 areas now. They are on an exterior wall and I didn't want to mess with the insulation and drywall to install two more outlets. With the low voltage units I can drill through cabinets and have 18 ga zip cord hidden inside. So it makes sense for me to use the Slowes pucks.

To deal with the AM radio issue I'm making them as easy as possible to turn off. I'm setting up touch systems for the three circuits, with a contact wired to three cabinet knobs. I installed old work boxes for the line voltage circuits that have little side pockets where I can hide the electronics.

I appreciate your help on the lamps that you found at *******. Hopefully they will be available here soon for my next project.

edlentz
10-07-2008, 07:35 AM
I can sympathize with "she changed her mind" Fortunately for me I had ripped out the old drywall to the studs and have switched outlets in my cabinets. Anyway, good luck next time

Ed

Southern Man
10-07-2008, 08:02 AM
I can sympathize with "she changed her mind" Fortunately for me I had ripped out the old drywall to the studs and have switched outlets in my cabinets. Anyway, good luck next time

Ed
After 22 years and many projects I've come to the realization that I need to come as close as I reasonable can with a "mock up" before she 'll make a decision. She, in turn, has come to the understanding that once her decision is made I will resist with at least as much effort that it took me to develop said mock up. :D

Southern Man
10-24-2008, 06:20 AM
I now have a problem with the switches for these lights: http://www.terrylove.com/forums/showthread.php?p=163132#post163132

Thatguy
10-24-2008, 09:50 AM
1. Is the 34V still considered low voltage?
3. The pucks get pretty hot so I'm not sure how energy efficient they actually are.

1. Below 30vrms, 42vpeak, 60vdc the NEC relaxes some rules.

3. The hotter they get the shorter the lifetime. The service lifetime halves for each 10C rise above ambient. This is a manufacturer's tradeoff. They might be more efficient (watts in vs. light out) at higher temps.

xianying49599
10-30-2008, 03:36 AM
hi ,

there are many creative LEDS in www.elementalled.com

Rgs

Anna