Fast way for L.E.D.'s
09-10-2006, 09:14 AM
#1
Fast way for L.E.D.'s
Im sure that someone has already come up with this somewhere, but I did not check. This dawned on me at 2 this morning when I was laying in the bed. I have tried to sauder L.E.D.'s before, but I suck after about 10 min. of it. This way all you have to do is put some duct tape or something over it to protect the leads. Tell me what you think, and if this already exists, let me know.
09-10-2006, 11:45 AM
#5
Things you need:
Speaker wire
Thumb tack (to punch holes through wire)
Electrical Tape (to wrap it all up)
Punch a hole in each side of the speaker wire where you want the led to sit. Make sure that you always use the the same side for (+) and the same side for (-) Slide the prongs of the led through the correct side of the wire and then wrap the leads back around the wire. Test the led's as you go, and then wrap in either electrical or duct tape around everything just to protect the leads.
I think I will try to mount this onto some type of....well I don't know yet really. This method is more for a straight line of led's. Depending on how much you want it to bend, that is how flexiable the mounting surface needs to be. This is all still a work in progress let me know if you have any ideas to improve on this.
Speaker wire
Thumb tack (to punch holes through wire)
Electrical Tape (to wrap it all up)
Punch a hole in each side of the speaker wire where you want the led to sit. Make sure that you always use the the same side for (+) and the same side for (-) Slide the prongs of the led through the correct side of the wire and then wrap the leads back around the wire. Test the led's as you go, and then wrap in either electrical or duct tape around everything just to protect the leads.
I think I will try to mount this onto some type of....well I don't know yet really. This method is more for a straight line of led's. Depending on how much you want it to bend, that is how flexiable the mounting surface needs to be. This is all still a work in progress let me know if you have any ideas to improve on this.
09-11-2006, 11:02 AM
#9
Member
Join Date: Feb 2006
Posts: 43
How are you limiting current to the LEDs?
If you're running those LEDs near their max currents (25-30mA), expect some dead ones after a while. You're placing them in parallel with no resistors on each, not a good way to run them. The forward voltage of each LED is slightly different than all of the others, which means you're going to force every one in the chain to run at the same forward voltage (an average of the individual Vf's). Unless you matched the Vf's carefully by hand, some will draw more (some less) current than the average and will burn out eventually.
FYI...
If you're running those LEDs near their max currents (25-30mA), expect some dead ones after a while. You're placing them in parallel with no resistors on each, not a good way to run them. The forward voltage of each LED is slightly different than all of the others, which means you're going to force every one in the chain to run at the same forward voltage (an average of the individual Vf's). Unless you matched the Vf's carefully by hand, some will draw more (some less) current than the average and will burn out eventually.
FYI...
09-11-2006, 11:36 AM
#10
Another easy way to accomplish the LED effect is to look for computer illumination kits. These are already 12 volt setups. In my car, I used two cold cathode tubes to illuminate my amprack, then I used two 5-LED arrays to light up the area around my subs.
This is the process for my amprack
This is the process for my amprack
09-11-2006, 11:46 AM
#11
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=6846890389
That is where I got the cold cathodes, and this is where I got the LED's
Both are 12 volt
http://cgi.ebay.com/Blue-5-LED-LAZER...QQcmdZViewItem
Here is the finished product. It looks much cooler at night.
That is where I got the cold cathodes, and this is where I got the LED's
Both are 12 volt
http://cgi.ebay.com/Blue-5-LED-LAZER...QQcmdZViewItem
Here is the finished product. It looks much cooler at night.
09-11-2006, 12:05 PM
#12
Originally Posted by MacGyverS2000
How are you limiting current to the LEDs?
If you're running those LEDs near their max currents (25-30mA), expect some dead ones after a while. You're placing them in parallel with no resistors on each, not a good way to run them. The forward voltage of each LED is slightly different than all of the others, which means you're going to force every one in the chain to run at the same forward voltage (an average of the individual Vf's). Unless you matched the Vf's carefully by hand, some will draw more (some less) current than the average and will burn out eventually.
FYI...
If you're running those LEDs near their max currents (25-30mA), expect some dead ones after a while. You're placing them in parallel with no resistors on each, not a good way to run them. The forward voltage of each LED is slightly different than all of the others, which means you're going to force every one in the chain to run at the same forward voltage (an average of the individual Vf's). Unless you matched the Vf's carefully by hand, some will draw more (some less) current than the average and will burn out eventually.
FYI...
09-11-2006, 06:52 PM
#15
What if I did it like this? (there is actually 22 LED's in all....I did not feel like drawing the rest)
If each LED makes it drop ~4V would this work? Actually I know it will work, but what about the milliamps on this one?
If each LED makes it drop ~4V would this work? Actually I know it will work, but what about the milliamps on this one?
09-11-2006, 06:57 PM
#16
I wouldn't recommend doing 2 in series and the rest in parellel, in fact i don't even think it would work the way you're showing it. You'd have to do it all one way or all the other, and consider adding resistors
09-12-2006, 07:10 AM
#18
Supporting Maxima.org Member
Join Date: Nov 2001
Location: SoCal
Posts: 653
Even with them all in parallel they will last a long time (1k+ hours runtime, provided you limit the current to acceptable levels), just not as long as MacGyver likes them to last. Personally, I wouldn't set it up the way you have it drawn out though.
I'd either put one ~16.5 Ohm resistor where your series LED (coming from the + terminal) is, get rid of the other series LED, and put all the LED's in parallel.
Or, (better way, but takes more work) put all of your LED's in parallel with 400 Ohm resistors in series with the LED's.
(+ ----- 400 Ohm Resistor ------ LED ----- GND) [22 of those <--- in parallel]
You could also do
(+ ----- 200 Ohm Resistor ----- LED ----- LED ----- GND) [11 of those <--- in parallel]
I'd either put one ~16.5 Ohm resistor where your series LED (coming from the + terminal) is, get rid of the other series LED, and put all the LED's in parallel.
Or, (better way, but takes more work) put all of your LED's in parallel with 400 Ohm resistors in series with the LED's.
(+ ----- 400 Ohm Resistor ------ LED ----- GND) [22 of those <--- in parallel]
You could also do
(+ ----- 200 Ohm Resistor ----- LED ----- LED ----- GND) [11 of those <--- in parallel]
09-12-2006, 08:22 AM
#19
Member
Join Date: Feb 2006
Posts: 43
Originally Posted by D Love
Even with them all in parallel they will last a long time (1k+ hours runtime, provided you limit the current to acceptable levels), just not as long as MacGyver likes them to last.
Running single LEDs in parallel with others (with no current-limiting resistor) is just an all-around bad idea. Depending upon the LED's published nominal specs and counting on them to drop exactly the voltage you want/need is also a bad idea, not to mention your supply voltage will obviously change with car on/off.
09-12-2006, 09:37 AM
#20
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Join Date: Nov 2001
Location: SoCal
Posts: 653
Originally Posted by MacGyverS2000
That depends on the Vf of the LEDs... if one or two are far outside the norm (lower Vf), they may last a few tens of hours as you pump 50%, 100%, or more of the rated current through them.
Running single LEDs in parallel with others (with no current-limiting resistor) is just an all-around bad idea. Depending upon the LED's published nominal specs and counting on them to drop exactly the voltage you want/need is also a bad idea, not to mention your supply voltage will obviously change with car on/off.
Running single LEDs in parallel with others (with no current-limiting resistor) is just an all-around bad idea. Depending upon the LED's published nominal specs and counting on them to drop exactly the voltage you want/need is also a bad idea, not to mention your supply voltage will obviously change with car on/off.
09-12-2006, 03:47 PM
#23
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Join Date: Nov 2001
Location: SoCal
Posts: 653
Originally Posted by BLK2BLU
I have a guy telling me this...Run 5 legs of 4-LEDs (in series) parallel; this way you will be able to avoid using a resistor. (the guy is metal maxima)
Personally, I would not run your LED's without a current limiting resistor. However, Metal has used many many LED's in his mods, and if this is how he's done them, then you might want to try it. The worst that can happen is an LED or two burns out and you have to re-do it.
09-12-2006, 04:04 PM
#24
Originally Posted by D Love
One problem with Metal's way is that you said the voltage drop across the LED's is 4V, and with 4 LED's in series, there would be a drop of 16V if they were all on.
Another problem with running them without a resistor is that your car's battery fluctuates between what, 12 and 14+V
Without a resistor in series with the LED's, you have nothing but the LED's to "absorb" that extra voltage.
However, Metal has used many many LED's in his mods, and if this is how he's done them, then you might want to try it. The worst that can happen is an LED or two burns out and you have to re-do it.
Personally, I would not run your LED's without a current limiting resistor.
09-13-2006, 08:55 AM
#27
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Join Date: Nov 2001
Location: SoCal
Posts: 653
Originally Posted by Metal Maxima
Blue LEDs run between 3.0 to 3.4V.
(3.4V)(4) = 13.6V < 12V...I have yet to see my Max run above 12.68 volts.
(3.4V)(4) = 13.6V < 12V...I have yet to see my Max run above 12.68 volts.
Originally Posted by BLK2BLU
If each LED makes it drop ~4V would this work?
Originally Posted by Metal Maxima
Not so. LEDs fail due to thermal runaway caused by an excess amperage supply to the LEDs. Even if you are running @ 14.4V, you won't exceed 30mA, which LEDs are full well capable of withstanding, SO you'd be good to go.
Personally, I would not run the LED's without current limiting resistor(s). If I were you, I'd have 22 LED's, and 22 resistors (470 Ohm, 1/4W). I'd really rather use 430 Ohm resistors, but you would have to go down to tolerances of 5% to get those values (unless you hand pick the 470 Ohm resitors), and Radio Shack only has the 10% tolerance resistors.
09-13-2006, 08:57 AM
#28
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Posts: 653
Originally Posted by BLK2BLU
What about 4 legs (in series) with 5 led's (in parallel) on each leg?
09-13-2006, 10:07 AM
#29
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Join Date: Feb 2006
Posts: 43
Originally Posted by D Love
If this is working for you, then basically you're just lucky, and your LED's are very near their turn on voltages. The I-V graph for diodes has an exponential nature. This means that at low voltages there is a small leakage current through the diode. However, as you approach, and surpass, the turn on voltage of the diode, the current will rise exponentially.
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