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Old May 13, 2012, 10:47 PM
Crash and learn
United States, PA
Joined Dec 2011
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Toy 2-LED Dragonfly for V911 night flying

Toy 2-LED Dragonfly for V911 night flying.

SIZE: The propeller part is the same diameter as the V911 blade diameter. The blade hub slides firmly down over the V911 flybar.

LEDs: Easily disassembled by gently pulling the plastic pieces apart. The electronics are two LEDs, one on each side, a core of three AG1 Button Cell Batteries (alkaline 13mah), and a very strong eyelet screw that turns into the batteries connecting one set of LED leads to the battery. Eyelet screw switch works very well to turn LEDs on and off, so precise it can even be set to switch on vibrations.

The LEDs are parallel with the battery and are actually blinding at arms length. They are the floodlight kind, 4 inch circle at 1 foot distance, another 8 inch circle at 10 feet, 3.14 volts across the LEDs, eyelet is (-). No resistor. Non-blink blue LEDs on the one I pulled apart. Two LEDs lit, no heat.

Each LED (+) end will slide out of the plastic leaving the other LED still functional. Each LED (-) end unwraps from the eyelet with a half twist.

NOW THE GOOD PART.
The LEDs must have internal resistors because they work fine across a V911 stock battery. No heat, just blinding light. And no damage if you connect backwards.

So, for $0.38 each, you get two floodlight LEDs with internal resistors and a 3 cell battery. Tape a few of these units to the v911 for night flying and when the battery is dead, wire the LEDs to the LiPo 3.7 volt battery.

Have not timed them, likely will last at least one night session. One LED 80 minutes. Two LEDs 40 minutes.

Toy 2LED Dragonfly
http://www.aliexpress.com/product-fm...olesalers.html
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NOW THE BAD NEWS

Measured 70ma with one LED across a newly charged 4.15 volt V911 LiPo battery.
LiPo voltage under load = 4.13 volts with one LED.
LiPo voltage was still 4.15 volts after test.

Two LEDs in series across the V911 LiPo battery just barely lit.

The LED burned out instantly across a 7.4 volt LiPo. One flash, no heat.

Two LEDs in series across 7.4 volt LiPo battery works fine.

A 130mah V911 battery should light the LED for about two hours. Uses about 7mah per 6 minute flight, which is about 5% reduction in flying time per LED.

Using 3 cell original battery 3.50 volts = 10ma per LED. Various LED colors, mostly blue, some red/blue blinking, many solid red, some green. All floodlight type LEDs and all blinding bright at arms length. Total 120 LEDs, 60 three cell batteries, and 60 plastic"helicopters" left over after removing the electronics.
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Taped the remaining single LED and 3 cell package to the nose of a V911 and did a night flight. Weird, but worked great. The blue LED was very visible except when the V911 was tail in and all I saw was the red V911 LED. The degree of tail in or nose in was easy to see. Nose in, the blue LED floodlight was brightest when directly pointing at me and dimmed as the V911 turned to the side. Flew out as far as I normally fly, out to the edge of my yard (20 meters, 60 feet) and orientation was easier than in daylight. Should work fine for long distance orientation at the park. Much better results than I expected. Looking forward to some cool night flying in a hot summer.
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V911 Notes:
Tail motor Red (+) Blue (-) Battery 3.89v
Tail motor no blade = 51ma
Tail motor with blade = 750ma
Tail motor stalled = 1100ma

Main motor with blades = 1100ma
Main motor stalled = 2200ma

9958 Motor (5.00g)
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Last edited by Ribble; Jun 21, 2012 at 11:20 PM.
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