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.
LED cabinet lighting
- Thread starter Southern Man
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Southern Man
DIY Hillbilly
Thanks. I just sent them an an email to see if they'd mail me some.
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Like an engineer
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.
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.
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.
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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.
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.
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.
Southern Man
DIY Hillbilly
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.
Southern Man
DIY Hillbilly
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.
Southern Man
DIY Hillbilly
I now have a problem with the switches for these lights: https://terrylove.com/forums/showthread.php?p=163132#post163132
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 10°C rise above ambient. This is a manufacturer's tradeoff. They might be more efficient (watts in vs. light out) at higher temps.
