- #1
Terranova
- 6
- 0
Hello, my name is Mike, and I have just enough electrical engineering knowledge to be dangerous. This season I have inherited a programmable LED Christmas light set up from my father-in-law who is no longer with us to help guide me with his EEngeneering knowledge.
Here's the issue.
I have multiple strings of Red, Green, Blue and White LED Christmas lights that I would like to shorten to "custom" lengths in order to fit "precisely" around windows, gables etc.
(here's the little knowledge is dangerous thing)
I know that it is possible to remove x LEDs and put a resistor in line to drop enough voltage to not fry the rest of the LEDs with to much current. I've read several things on several forums, none of which have been thorough enough process wise or "dumbed down" enough for me to understand exactly what I need to do in order to figure out how to calculate the size resistors I will need.
Im having trouble synthesizing everything I've read into knowing what I need to do for my specific situation.
Yes OHMs law, led resistor calculators etc.
I don't know the voltage drop(?) for each color because I don't have a spec sheet for the LEDs.
Here's what I do know (insert snarky comment here)
Each strand is roughly 24' long with approximately 4" between each LED.
120v AC
They flicker, so I assume they're not rectified.
I do not have a true spec sheet for the LEDs, per say, but I do have partial info from manufacturer lit stating that the string is rated at 4.8 Watts (0.04 amps)
There are 70 M5 LEDs per string.
The Greem strings have no resistors in line that I can find.
The R/B/W strings each have three resistors in line. One in the middle, and one at each. end between the plug and first LED, dividing the strings into what I assume (according other info I've read on the net) are two circuits of 35 LEDs.
There are (on the R B W) two wires from the plug to the first resistor. From there the LEDs are wired in series and the two other wires run uninterrupted to the next resistor.
The LEDs are not able to be removed from their sockets
I have a multimeter and I am not afraid to destroy a string or two to find the info I need. I've already destroyed a white string trying to get to the inline resistor. That failed miserably.
How do I go about figuring out how much ( here's where I'm confused) voltage or current (?) each color LED uses so I can multiply that figure to come up with a resistor?
I'm apologize if my tone is a little frantic or frazzled but this has been vexing me for over a week.
Thanks,
Mike T.
Here's the issue.
I have multiple strings of Red, Green, Blue and White LED Christmas lights that I would like to shorten to "custom" lengths in order to fit "precisely" around windows, gables etc.
(here's the little knowledge is dangerous thing)
I know that it is possible to remove x LEDs and put a resistor in line to drop enough voltage to not fry the rest of the LEDs with to much current. I've read several things on several forums, none of which have been thorough enough process wise or "dumbed down" enough for me to understand exactly what I need to do in order to figure out how to calculate the size resistors I will need.
Im having trouble synthesizing everything I've read into knowing what I need to do for my specific situation.
Yes OHMs law, led resistor calculators etc.
I don't know the voltage drop(?) for each color because I don't have a spec sheet for the LEDs.
Here's what I do know (insert snarky comment here)
Each strand is roughly 24' long with approximately 4" between each LED.
120v AC
They flicker, so I assume they're not rectified.
I do not have a true spec sheet for the LEDs, per say, but I do have partial info from manufacturer lit stating that the string is rated at 4.8 Watts (0.04 amps)
There are 70 M5 LEDs per string.
The Greem strings have no resistors in line that I can find.
The R/B/W strings each have three resistors in line. One in the middle, and one at each. end between the plug and first LED, dividing the strings into what I assume (according other info I've read on the net) are two circuits of 35 LEDs.
There are (on the R B W) two wires from the plug to the first resistor. From there the LEDs are wired in series and the two other wires run uninterrupted to the next resistor.
The LEDs are not able to be removed from their sockets
I have a multimeter and I am not afraid to destroy a string or two to find the info I need. I've already destroyed a white string trying to get to the inline resistor. That failed miserably.
How do I go about figuring out how much ( here's where I'm confused) voltage or current (?) each color LED uses so I can multiply that figure to come up with a resistor?
I'm apologize if my tone is a little frantic or frazzled but this has been vexing me for over a week.
Thanks,
Mike T.
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