Derek's HK Dart 250 FPV Mini Quad

[Derek]

not me 1000mah 4s only

I did order two 4S 1300mah 40C packs, along with some other stuff. Those "should" be here tomorrow.

[Derek]

If you didn't or haven't set up a low voltage buzzer on your flight controller, but you still want a low voltage buzzer on your quad....see what I did here:

https://www.youtube.com/watch?v=8a_N1j2mGXA

[Tony]

Good job D. Does it work under water...lmao

[cml001]

Lol

[Derek]

I dunno, Tony. I've been pretty good about staying AWAY from the water, lol

[Derek]

I was at work last night and I had a thought....it wasn't an "over-thought", lol....just a thought. I have yet to try my Dart 250 with a 4S lipo and I'm realizing how glad I am that I haven't tried a 4S lipo yet....because my LED's are wired directly into the mix. My LED's are only rated for up to 12v. Surely the 14.8v from a 4S pack would fry the LED's. It looks like it's time to order a small BEC. I have a Castle 10amp BEC, but I'm gonna keep that around for a larger model. I imagine a small 3amp BEC would suffice to power my LED's.

[Tony]

you could just buy a resistor to drop the extra voltage Derek, simple enough. although i think the Leds would be OK at 15volt...

do you have a current meter to measure the current drawn by the Leds alone... then we can work out the resistor size based on the voltage drop we need

we need to drop 2.8 volt. so divide the 2.8 volt by whatever current reading you get, this will give the ohm value of the resistor. then multiply the 2.8 x the current reading to give you the wattage of the resistor...

lets say for instance the current your leds are using is 100mA or 0.1 amp

so 2.8v / 0.1 = 28 ohms, so id use a 27 Ohm (common size)

wattage = volts x current = 2,8 x 0.1 = 0.28 watts, or 280 mW,

i would get a 1 watt 27 Ohm resistor....

just stick it in series with the positive supply..

simplz

[cml001]

Ooouuuu!

[Derek]

Holy crap!!! My head is spinning now because of what Tony just posted, ha ha ha!

[Tony]

its simple math(s) man.... good grief... haha, tell me what current those leds are drawing from your pack and ill show you how to calculate it...

[Derek]

the equation "1 + 1 = 2" is simple math, Tony, ha ha ha...That stuff you were talking about made me dizzy, lol. I wouldn't even know how to measure the current from the LED leads.

[Tony]

We'll send me a link to the ones you have, most leds draw around 20mA each..

You could just stick a 12 volt regulator in it, has 3 pins. In, out and ground.... Simplz....

[Derek]

Here is a link to the blue lights that I'm using:

http://www.buddyrc.com/extra-bright-blu ... strip.html

I also have white, red, and green.

[cml001]

That's the ones I got... Very bright! Day or night.. I can see'm

[Derek]

Yeah...they are great LEDs

[Tony]

Ok so there's 60 leds per meter, they all draw 800mA, so 800 / 60 = 13mA each, so how many are you using in total, back and front?

You could buy one of these, it will do the full 1 meter if needed but would need a heatsink..

If you only have a dozen or so it will be fine.... Simple to wire up...

http://pages.ebay.com/link/?nav=item.vi ... 1555981146

[Derek]

I have 6 blue LED's on the rear and 6 white LED's on the front.

[Tony]

I have 6 blue LED's on the rear and 6 white LED's on the front.

Ok, so 12 leds. Well white and blue generally consume more current that other colours so I'll say 20mA per led x 12 = 240mA. So without confusing you, you need a resistor value of 12 ohms @ 1 watt... Put this in series with the positive wire...

[Derek]

Ok. I'll see if I can hunt one of those down. I'd really like to be able to run 4S on my quad but I surely don't want to burn out my LED's.

[Stambo]

Would not be hard to incorporate a removable resistor on a couple of JST plugs so while you run 4s you put it in and when you are back on 3s you take it out. Would also mean you could have the lights unplugged while you don't need them.