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HK Backlight Mod

Posted: Fri Dec 07, 2012 3:34 am
by JamesPal
I have the white Hobbyking backlight. The difference between the front and back is not apparent. It appears to have white plastic on both sides. Is there a front or back? Do the plastic covers stay with the light or do I remove them?

Re: HK Backlight Mod

Posted: Fri Dec 07, 2012 5:33 am
by Scott Page
I'm a maverick in this regard, but I remove them and put a piece of reflective paper behind the light to direct more light where I want it rather than being absorbed by the black sponge behind it. to make reflective paper I use contact adhesive on heavy paper, and adhere alum foil shiny side out. cut to fit.

Re: HK Backlight Mod

Posted: Fri Dec 07, 2012 2:46 pm
by JamesPal
Scott,
thanks for the tip. I will add a whate paper background.

Q, I intend to install the Gruven9X board along with my backlight. I was looking at the Wiki on the HK backlight. What is the purpose of the resistor and do I need to add that? http://openrcforums.com/wiki/index.php/ ... r_9x_radio

Re: HK Back light Mod

Posted: Fri Dec 07, 2012 4:59 pm
by ShowMaster
I usually apply 5-10 volts to the BL before I install and mark the brightest side. The reflective backing addition is not a bad idea but still there is a bright and darker side.
SM

Re: HK Backlight Mod

Posted: Fri Dec 07, 2012 6:03 pm
by JamesPal
SM, do you add the resistor as shown http://openrcforums.com/wiki/index.php/ ... r_9x_radio?

Re: Sv: HK Backlight Mod

Posted: Fri Dec 07, 2012 7:17 pm
by dvogonen
There is nothing magical about the back light. It is simply two LEDs mounted on the end of a piece of transparent plastic. If you connect them directly to power they burn out instantly. You always have to connect a resistor in line with LEDs to prevent to much current rushing through the circuit.

Re: HK Backlight Mod

Posted: Fri Dec 07, 2012 10:36 pm
by ShowMaster
JamesPal wrote:SM, do you add the resistor as shown http://openrcforums.com/wiki/index.php/ ... r_9x_radio?
Yes you must have a current limiting resistor in series. The HK has a 470 ohm resistor and it must be there for tx voltage source.
What I do is use probes and apply a 5-12 volt voltage to the same pins the 9x would use. I'll have to look it up if it's needed since I wing it when I do it.
I do find that one side is always brighter.
SM


ShowMaster
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