Home Made LED controller - RC Groups
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Mar 07, 2012, 08:39 AM
If in doubt, add accelerant
Lberry.88's Avatar
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Home Made LED controller


Has anyone got a design for a system that can turn a light array on and off via a TX channel? Would like to be able to turn them on and off and so far have only been able to find google results that cost a fair bit...

Anyone point me in the direction of a supplier or a set of schematics?
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Mar 07, 2012, 08:57 AM
Not failing=Not trying enough
Wehrdo's Avatar
I've looked into this a little bit and the best I've found(but haven't tried myself) is to take an old servo and open it up. Then cut the leads that run to the little motor and connect them to a 5V relay instead. When the servo is connected to a switch channel on your receiver, it should turn the relay on and off.

Like I said, I've never tried myself, but some things that would need to be considered is the position of the potentiometer feedback shaft, which would probably have to be all the way left or right. Another thing to consider is if you wanted to dim the lights, you might want to try connecting a transistor to the leads instead, so they PWM meant for the motor carries to the LEDs.

Are you using a premade LED strip?
Mar 07, 2012, 09:26 AM
Registered User
ausf's Avatar
Quote:
Originally Posted by Lberry.88

Anyone point me in the direction of a supplier or a set of schematics?
I'd love this myself. I wouldn't think it would be too difficult, but far beyond my scope of understanding. I bought a set and installed in my UM F4U. It plugs into the aux port, so I wrongly assumed I could control it vis the gear switch.

The easiest way I can think of is installing a micro switch and tripping it by servo, but it's not that important to me to add the weight.

Some UM lighting kits have flashing LEDs for simulated gunfire, there's got to be a relatively simple way.
Mar 07, 2012, 09:52 AM
Registered User
you most definitely can use an old servo driver board i do it all the time.. but you dont need the relay ect

just unsolder the motor from the board solder your LED's to that connection point and adjust the pot till the lights are off when the switch is in the desired position then just lock the pot in place with a drop of glue OR read the resistance at that position and use the matching resistor and do away with the pot altogether

the neat thing is because its a servo driver its variable voltage so you can adjust your endpoint to make them dimmer/brighter

for low draw LED's 1A or less i use old busted micro servo boards IE those 3$ servos from HK

good luck
Tim
Mar 07, 2012, 11:50 AM
Not failing=Not trying enough
Wehrdo's Avatar
Quote:
Originally Posted by turbored21
for low draw LED's 1A or less i use old busted micro servo boards IE those 3$ servos from HK

good luck
Tim
Can the servo board on those 9g servos handle that much current? The reason I thought a relay would be good is you can connect an external power source and not worry about overloading BEC, receiver, or servo controller.
Mar 07, 2012, 12:21 PM
If in doubt, add accelerant
Lberry.88's Avatar
Quote:
Originally Posted by turbored21
you most definitely can use an old servo driver board i do it all the time.. but you dont need the relay ect

just unsolder the motor from the board solder your LED's to that connection point and adjust the pot till the lights are off when the switch is in the desired position then just lock the pot in place with a drop of glue OR read the resistance at that position and use the matching resistor and do away with the pot altogether

the neat thing is because its a servo driver its variable voltage so you can adjust your endpoint to make them dimmer/brighter

for low draw LED's 1A or less i use old busted micro servo boards IE those 3$ servos from HK

good luck
Tim
Sounds like a neat solution - I'll give it a try at the weekend - sure beats my Push To Make switch idea using a servo etc!

Thanks, I'll report back with success (hopefully)
Mar 07, 2012, 02:38 PM
Registered User
If you're interested, you can make your own circuit using a programmable PICAXE chip http://www.picaxe.com/. The beauty of going this route is that the chip can be programmed to react to any input from the receiver (i.e. proportional, not just on/off), and can then be programmed to initiate any action. The chip itself can handle 20mA loads through its four outputs, if I remember correctly, but by adding simple output transistors you can design it to handle any load you want.

I recently programmed one to count down 7 minutes flying time whenever my heli throttle is above about 30%, and to progressively switch off 4 leds so I can see how the time's going. I can't hear the timer on my trannie when I'm hovering close by.

A while back I built another circuit that runs three sets of strobe lights plus a switchable pair of landing lights.
Mar 07, 2012, 03:17 PM
Winter Haven FL
Byrdman's Avatar
If you dont want to do it yourself, here is one http://www.hobbyking.com/hobbyking/s...idProduct=8833
Mar 07, 2012, 04:47 PM
Registered User
ausf's Avatar
Quote:
Originally Posted by abenn
A while back I built another circuit that runs three sets of strobe lights plus a switchable pair of landing lights.
Would you have a schematic or link of that?
Mar 07, 2012, 06:03 PM
If in doubt, add accelerant
Lberry.88's Avatar
Quote:
Originally Posted by Byrdman
If you dont want to do it yourself, here is one http://www.hobbyking.com/hobbyking/s...idProduct=8833
Brilliant cheers - was looking around HK but couldn't find the right thing to search for!

Wehrdo - your plan worked - opened up a servo - unsoldered the motor and added an LED - worked Will now experiment with current draw etc: shrink wrap the circuit board and add a JST plug for convenience. Thanks for the advice.
Mar 07, 2012, 06:20 PM
Not failing=Not trying enough
Wehrdo's Avatar
Quote:
Originally Posted by Lberry.88
Wehrdo - your plan worked - opened up a servo - unsoldered the motor and added an LED - worked Will now experiment with current draw etc: shrink wrap the circuit board and add a JST plug for convenience. Thanks for the advice.
Glad it worked. I might actually need to do that this weekend. Even though the days are getting longer, I could then fly once the wind goes down.


Don't forget a resistor on the LED, unless you can keep the voltage at 2.0V(depending on what LED, could be different) If not, you'll exceed the rated current(usually around 20mA) and burn them out. If you're not already, I would recommend using one of those LED strips. They're surface mount devices which make them lighter, and have built in resistors. Hobbyking and HobbyPartz both have them, if you're looking for cheap.
Mar 07, 2012, 07:04 PM
Wake up, feel pulse, be happy!
Piece's Avatar
ValueHobby also has the light strips. I got a blue one for $5.50 and it's pretty awesome.

They can be snipped down to strings of three (with a resistor already in place for 12V input) but I'd imagine a person could pluck the individual LEDs off it for use in smaller applications or lower voltages.
Mar 07, 2012, 07:56 PM
Registered User
tacx's Avatar
Quote:
Originally Posted by Lberry.88
Has anyone got a design for a system that can turn a light array on and off via a TX channel? Would like to be able to turn them on and off and so far have only been able to find google results that cost a fair bit...

Anyone point me in the direction of a supplier or a set of schematics?
LBerry88,
Here is a simple setup that many of the glow guys use to switch on thier "on-board glow" system. It is just a micro switch you can get at Radio Shack mounted next to a small servo. They cut down a servo arm so it has a lobe to it. Then they connect the servo to a free channel on their RX. Here is a pic of one.
Mar 07, 2012, 08:21 PM
Not failing=Not trying enough
Wehrdo's Avatar
C4H10(Should I call you butane? ), thanks for pointing that website out. I think I might order some. Is there anyway to modify those to work on 5V without a lot of headache and trouble? That would let me connect through the receiver.
Mar 07, 2012, 08:46 PM
Wake up, feel pulse, be happy!
Piece's Avatar
In their stock form they'd light up but probably wouldn't be very bright, but if you ran like two of the individual diodes in series without the resistor, the ~5V from the receiver would probably be just about right.

Running LEDs off a receiver/BEC can be tricky business. A couple is usually ok, but they do start to add up eventually.


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