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View Full Version : LED String Blade n00b with Clarification Questions



JesHoward
11-30-2015, 11:05 AM
Hi all! I've been lurking here for a while researching these amazing looking string blades and have decided to take a shot at it myself. I'm not the most electronics savvy, but I think I'm starting to get the hang of it and would love for someone to tell me if I'm on the right track. Firstly, this being my first string blade, I'm only looking for on/off functionality... no scrolling, no sound, no flash on clash. Just to have it turn on, not explode, and mesmerize moths for miles =] So here goes...

I'm looking at a pack of 100 LEDs on Amazon that are rated as "3.0~3.4V 20mA" so with, let's say, 50 of these wired in parallel I would need to calculate # of LEDs X current. 50x20mA = 1000mA. Okay now I'm thinking of the power packs. TCCS sells Li-ion packs that are 3.7V at the lowest... I'm guessing that these can't be used. Or am I wrong there? Next up would be the resistance. I can calculate the resistance needed and solder that in, but then the BuckPuck caught my eye. It's rated for 1000mA (yay!) but the minimum voltage input is 5V (aww). I'm guessing that's a bust too.

I'm really thinking that I'm missing something here, and my question is what that may be. I've been searching around, without much luck, on what is used to get this thing going and I'm coming up empty. Any help or shove in the right direction would be greatly appreciated!

Jes

rlobrecht
11-30-2015, 11:44 AM
no scrolling, no sound, no flash on clash. Just to have it turn on, not explode, and mesmerize moths for miles =]

Any reason why you want to do a string, instead of a single LED (or tri...)?

JesHoward
11-30-2015, 12:03 PM
Mainly I really like the look of the LED strings, crazy bright and even light. Also those features is something that I will be wanting eventually, but I'm starting at the bottom and trying to learn the basics of getting this system to work. I'd rather pay $10 in LEDs that I may destroy than the $130 for the CF-LS board and end up destroying that... my wife would freaking kill me =]

Silver Serpent
11-30-2015, 01:01 PM
If you wired them all in parallel, the 3.7v li-ion would power a set of LEDs that require 3.0-3.4v.

You typically will want to make the LED string in 5-6 segments, mostly for heat issues. You want very fine gauge wiring so it doesn't interfere with the light from your LEDs. Pumping 1000mA through the finest wire can cause overheating problems.

JesHoward
11-30-2015, 01:21 PM
Thanks for the info Silver Serpent! I've read that splitting up the string into segments was advised, but I wasn't quite sure why. This makes sense now. So if I have 5 segments of 10 LEDs each (10x20mA=200mA for each segment, meaning I should use a 27 ohm resistor, thanks for the sig link btw) would I wire it with 5 separate resistors, each running to a different segment? That seems to make sense... how would one wire that up? Seems weird to have 5 separate resistors hanging off of a single lead from a battery/switch.