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Question about the flashing LED..and it's replacement!
and other soldering tips anyone might have!
Tags: Syma X9
December 16, 2012 - 3:44 am

Yes, if you want to turn it off, you can just clip the wires and not have an led, but we're talking swapping them out. LED's and light bulbs aren't the same. If it was a "grain of rice" lightbulb, it'd be easy, but led's you have to take into consideration that if the voltage is too low, they don't turn on (i.e. too many led's for what voltage you have) if you buy one that's not rated for a high enough voltage, it'll just turn red for a second and then be a dud.

December 16, 2012 - 2:26 am

If the light is annoying you and you want it off, either clip the lead wire going to the bulb, or cover the bulb with some matching coloured paint or tape so you dont see it.

My Propel Gyropter has lights all around it, instead of just the one light in the front of my Syma.

This isnt rocket science really.

How many ____________ does it take to change a light bulb? ¬†ūüôā

September 26, 2012 - 3:28 am

i could be wrong, but i think you may be over complicating this slightly. someone else chime in here..


say we've got a full battery with 4.2v and lets be conservative and say we're using a red or yellow LED that needs 2.0v at 20mA to turn on.


V=I*R is the same as V/I=R is the same as (VoltageTotal-VoltageLED)/I=R


So we get (4.2-2.0)/0.02=110ohm. If we wanted 20mA through the LED, we'd need a 110ohm resistor.  Since the one on the board is 180ohm, we can use the equation again (4.2-2.0)/180=0.012mA.  Also, since the heli is battery powered, this value would decrease over the course of the flight as the voltage in the battery falls.  At the end, there would only be ~(3.7-2.0)/180=0.0094mA running through the LED.


With a blue or white LED that usually need 3.0-3.6v to turn on, (4.2-3.0)/180=0.006mA.


Because the resistor is a known value, the only thing that would change would be the current through the LED depending on the voltage needed to turn it on and the voltage of the battery.


So I'm fairly certain it's okay.  Maybe we could get Raptor in here to say a few things?

September 26, 2012 - 1:51 am

Ok, 180 ohm resistor means that you need to take the voltage over the resistor too.


You have a certain voltage to work with, and Voltage=Current X Resistance. You have the voltage over the LED, then can get the voltage dropped over the resistor with the voltmeter. Whatever that total voltage is, that's the voltage you have to work with at maximum with your LED's.


It sounds simple, but there's a fair bit of math involved. Now, if you decide to put more or less than the voltage in the stock LED into the circut, you'll have to get the voltage needed to be dropped. That's where I'm a little rusty on my math, and if I remember right, I was using a table for that...


You would have to take the total voltage, and the current through the original circut. Then the voltage equals the current times the resistance. You have the voltage that needs dropped for proper operation of the LED's, and the current that is in the original circut at that voltage and resistance. All you need to do then is just plug in the voltage and current into the equation and get the value for the resistance you need to bring down the voltage, or up the voltage. Just need it to equal out in the end.


(although, like I said, if you manage to match the voltage of the stock LED, then you're golden and don't have to do a thing besides wire it up)

September 25, 2012 - 11:54 am

the solution to your question is pretty simple.


there is already a 180ohm resistor on the board...the tiny square next to the bottom pad of the negative battery terminal


just buy any 3mm led you want and solder it in place :)

September 24, 2012 - 1:43 am

I think (can't be sure) but I think that the LED on the heli has an internal diode that changes the color, but I just don't know.


As for adding or replacing the LED, what I do know is that you would have to find out what the voltage is over the LED, and then you can replace it. LED's are VERY voltage sensitive. If you don't have enough voltage, then they don't light. If they have just bearly too much, they blow out.


What I would do is run a voltmeter AND an ammeter across the source wiring joints for the LED. Then, I would figure out exactly what LED(s) you want, then go online for the store's site and see if they have them, and their voltage/resistance values. Now, when you add up the MAX voltages for the LED's, they have to be just slightly over the voltage for the stock led, and the minimum voltage has to be slightly under it.


I would, of course, double check what all else goes into it on the internet. I don't remember if you have to calculate the voltage using the curret.


I know down in the states we have Radio Shak, although I think I remember them being the same company as something like the sourse up in Canada.

Syma Freak
September 23, 2012 - 1:31 pm
Member Since: November 26, 2010
Forum Posts: 1443
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Three guys to say send email to,are Raptor,CPD,Supernova,especially Raptor for electric help..trying to find a post on the forum I think explained your idea..will search for it..SF

"Fly like a butterfly sting like a Syma" http://syma107.com

September 22, 2012 - 1:03 pm

Hi all.  Not really a problem, but I wanted to pick some brains as to the blue and red flashing LED on the 107. 

I would much rather have just a solid blue light, or perhaps a white one (more realistic searchlight)...or none at all!!  It's just a bit annoying when the heli is coming straight at you at eye level, and I would much rather be able to see the helicopter, and not the bright all encompasing flashes in low light conditions!

What I know about LED's would fit in the IR reciever hanging off the back of the circuit board!

So, question 1:  I'm assuming that the flasher responsible for the red blinking component is actually inside the LED..correct..or way off?

Question 2:  Can that flashing red component be switched off?

Question 3:  Would it be better to just find a nice blue LED..or a white one.... at an electronic store (like the Source here in Canada) and replace the stock LED?

Question 4:  If the flashing is ncontrolled by the LED itself, can I add micro LED red, green, and white 'realistic' nav lights by soldering to the existing LED wiring? (after eliminating the red flashing one from the front)


Question 5:  Am I better to go out and get a soldering 'pencil' for doing the insanely tiny soldering jobs I can see ahead!!!???  (my engineering side tells me that the little charging receptacle on the circuit board might be a weak spot over time and use!)

 And yes Syma Freak, I did watch your video on soldering, and have done some myself in the past on larger RC aircraft (some electrical, and wrapped wire around music wire landing gear.....big soldering gun...)

It's just that I'm seeing most of these pencils are over $100!!!  Maybe I can find a tiny tip for my gun! Confused


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