LED Christmas Tree Lights

[[email protected]]

Hi guys I purchased one of those invertors for the car that will run up
to 60 watts I tried hooking it up to a 12 volt battery from one of
those indoor emergency lights its rated at 6 a\hr. It would not start
up I guess I need something with a little more current. I have tried
in the past to wire the led lights in parallel but didn't have any luck
the first leds would light up but the others would not. I want to be
able to wrap my daughter up in a string of 100 so she can walk around
outside. Does anyone have any suggestions other then a long extension
cord?
Thanks Rick

 

[Michael Black]

Hi guys I purchased one of those invertors for the car that will run up
to 60 watts I tried hooking it up to a 12 volt battery from one of
those indoor emergency lights its rated at 6 a\hr. It would not start
up I guess I need something with a little more current. I have tried
in the past to wire the led lights in parallel but didn't have any luck
the first leds would light up but the others would not. I want to be
able to wrap my daughter up in a string of 100 so she can walk around
outside. Does anyone have any suggestions other then a long extension
cord?
Thanks Rick

You're going about it all wrong.

Get the raw LEDs, wire them up, and then connect it to a reasonable
sized battery. SHe can carry the whole thing around and the inverter
(and it's associated inefficiency) goes away.

The LEDs in the Christmas lights are no different from any old LED,
they need a couple of volts. But in order to run them off 120VAC, they
have to wire them so they can run off the higher voltage, which means
either putting them in series, or big dropping resistors (I don't
know how they do it). So in order to run those off a batter, you
need the inverter to step up the voltage, and then the LEDs in effect
step them down.

Making your own string of LEDs means you can wire them in parallel
(or at least in small substrings of only a few in series so they only
need 12v or so), and then run them off the battery directly.

You could even get fancy, and have some sort of sequencer to light
the LEDs in a sequence of some kind.

Michael

 

[[email protected]]

Thanks for the reply
I would like to use the inverter but like I said the battery that I
have I guess is not large enough. I dont really want to carry around a
car battery
How do I get the inverter to run on a small battery
Thanks
Rick

 

[[email protected]]

I got the inverter to work I used a 14 volt DeWalt Battery Pack from my
cordless drill. I have a 100 led string plugged into it and Im going
to see how long it will last
Thanks

 

[default]

I got the inverter to work I used a 14 volt DeWalt Battery Pack from my
cordless drill. I have a 100 led string plugged into it and Im going
to see how long it will last
Thanks

These things aren't really designed for clothing. How are you handling
the safety issues?

 

[[email protected]]

I was not aware that there were any. Led's do not get hot. What
would I have to worry about
Thanks

 

[feebo]

Hi guys I purchased one of those invertors for the car that will run up
to 60 watts I tried hooking it up to a 12 volt battery from one of
those indoor emergency lights its rated at 6 a\hr. It would not start
up I guess I need something with a little more current. I have tried
in the past to wire the led lights in parallel but didn't have any luck
the first leds would light up but the others would not. I want to be
able to wrap my daughter up in a string of 100 so she can walk around
outside. Does anyone have any suggestions other then a long extension
cord?
Thanks Rick

The failure to start could be down to the AC waveform...

If not a straight square wave, they are often optimistcally described
as a "modified sine" - which to my mind is a bloody lie. Scoping the
output of one such beast, it showed three levels: plus & minus volts
and a brief stay at Ov on the transition - great... a 1.5 bit sine
wave. That is some modification!

I think this is prosecutable as it really bears little resemblance to
a sine and should be described as a modified square wave - which it
undoubtedly is.

I have some mains stuff that really doesn't like running of my
inverter - but it is fine for lead-lamps and my electric saw etc.

 

[feebo]

I was not aware that there were any. Led's do not get hot. What
would I have to worry about
Thanks

depending on your current capabilty, a short can heat the wires up so
the insulation burns - way above the 60-70C human comfort/pain
threshold... your daughter could get burns if it develops a fault and
these might be nasty if they are "wrapped around" her and she cant get
them off quickly... at least put a fuse inline of the power

 

[Rich Grise]

I was not aware that there were any. Led's do not get hot. What
would I have to worry about

120 VAC from one side of your child's body to the other. This could be
lethal, and that is not a joke.

Pay attention here. Lose the inverter. Throw it away, use it in the car
while camping, anything, but do NOT strap a 120V inverter to a child.

Learn how to wire up LEDs for 12VDC. It's really not hard, and it's
worth the effort to read a book or so when your child's life is at stake.

Good Luck!
Rich

And in your spare time, you could learn to bottom-post, which is the
USENET convention.

 

[default]

Pay attention here. Lose the inverter. Throw it away, use it in the car
while camping, anything, but do NOT strap a 120V inverter to a child.

Learn how to wire up LEDs for 12VDC. It's really not hard, and it's
worth the effort to read a book or so when your child's life is at stake.

Ditto that

You couldn't get me in that rig . . . and I play with Tesla coils.

It just isn't smart to drape a child with 120 VAC wires. The battery
from the power pack is more than ample to kill. OK - the chance for a
short through a vital organ with enough current to kill is not too
likely, but it isn't non-existent either. Something totally
unforeseen can go wrong.

It only takes about 12 watts, hand to hand or, head to foot, to kill a
healthy adult.

If she's not electrocuted outright there's still a chance that a shock
at an inopportune time can cause a secondary, more serious, accident.

Wire the LEDs for low voltage, and if you are using a high current
battery pack protect the wiring with fuses and size it correctly to
keep it from burning.

 

[Baron]

Ditto that

You couldn't get me in that rig . . . and I play with Tesla coils.

It just isn't smart to drape a child with 120 VAC wires. The battery
from the power pack is more than ample to kill. OK - the chance for a
short through a vital organ with enough current to kill is not too
likely, but it isn't non-existent either. Something totally
unforeseen can go wrong.

It only takes about 12 watts, hand to hand or, head to foot, to kill a
healthy adult.

If she's not electrocuted outright there's still a chance that a shock
at an inopportune time can cause a secondary, more serious, accident.

Wire the LEDs for low voltage, and if you are using a high current
battery pack protect the wiring with fuses and size it correctly to
keep it from burning.

I agree ! Play safe !

 

[Rich Grise]

Ditto that

You couldn't get me in that rig . . . and I play with Tesla coils.

It just isn't smart to drape a child with 120 VAC wires. The battery
from the power pack is more than ample to kill. OK - the chance for a
short through a vital organ with enough current to kill is not too
likely, but it isn't non-existent either. Something totally
unforeseen can go wrong.

I was seeing her get splashed by a car going through a mud puddle.

But whatever - it's a bad idea for other reasons, like efficiency,
bulk, complexity, that sort of thing.

No Offense, OP, it's just that we do care, and there _is_ a simpler
way to do what you want.

Thanks!
Rich

 

[Rich Grise]

I was not aware that there were any. Led's do not get hot. What
would I have to worry about

Well, I don't know if you've been following the thread so far, but if
you feel like you've been left in the lurch, I'll apologize - I just
said, "Learn how to wire them for 12V", which was kind of curt. I'd
be happy to walk you through how to do that if you want to start
hacking your lights - that's kind of what s.e.basics is for.

Cheers!
Rich

 

[[email protected]]

Well, I don't know if you've been following the thread so far, but if
you feel like you've been left in the lurch, I'll apologize - I just
said, "Learn how to wire them for 12V", which was kind of curt. I'd
be happy to walk you through how to do that if you want to start
hacking your lights - that's kind of what s.e.basics is for.

Cheers!
Rich

I have being reading and I think that different colours are different
voltages is that right
If I want to run in on 12 volts I think that I wire about 4 in series
Is this how I would start
Rick

 

[Baron]

I have being reading and I think that different colours are different
voltages is that right
If I want to run in on 12 volts I think that I wire about 4 in series
Is this how I would start
Rick

Yes different colours have different voltages. Also the current
requirements are different for similar brightness.

If you are using a twelve volt battery, the fully charged voltage is
going to be around 13.5 v. Keep each colour LED in a single string.
Use a resistor to limit the maximum current in each string at the
maximum voltage.

So if you have a LED voltage of say 2.3v, that would allow a maximum of
5 LEDs in series or 11.5 volts. If the maximum current flow through
the string is 10 ma (0,01 amp) and 13.5v minus 11.5v = 2 volts. Then
the resistor will have to drop the 2 volts at 10 ma. Ie 200 ohms.

Use the same procedure for each string.

When you have completed your project, take a photo and let us all see
the results of your handiwork.

 

[default]

I was seeing her get splashed by a car going through a mud puddle.

Easy to imagine all kinds of tragic scenarios.

But whatever - it's a bad idea for other reasons, like efficiency,
bulk, complexity, that sort of thing.

He sounds like he wants a quick and dirty solution, and hasn't thought
it through.

 

[default]

I have being reading and I think that different colours are different
voltages is that right
If I want to run in on 12 volts I think that I wire about 4 in series
Is this how I would start
Rick

Check out
http://www.allelectronics.com/cgi-bin/item/LVL-2/search/LED_LIGHT_SHOW,_20_BARS_.html

http://www.allelectronics.com/cgi-bin/item/STR-8/search/FLASHING,_CYCLING_LED_STARS_(AS-IS)_.html

Read the critiques - the last seems like it may have a controller
problem

 

[Homer J Simpson]

I have being reading and I think that different colours are different
voltages is that right
If I want to run in on 12 volts I think that I wire about 4 in series
Is this how I would start

My dollar store has an assortment of battery operated flashing LED gadgets -
and the batteries. Might be quicker, easier, cheaper, safer.