Converting a Joystick into a Transmitter - RC Groups
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Jun 25, 2006, 07:10 PM
Volksflugen
Pelanconi Flyer's Avatar
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Converting a Joystick into a Transmitter


Don't ask me why I'm doing this; I'm not really sure. I am going to change the pots in this Thrustmaster PC Joystick and hook them to the encoder from my Spektum DX6 to create a "buddy box" of sorts. This way I can transmit the output of this Joystick through my Jr 6102DX.

So far I have identified the 4 pots that will control the ailerons, elevator, rudder, and throttle. They are 100k ohm and must be replaced with 10k to match the DX6s electronics. I have located a couple sources for the pots and I will order them tommorrow.

Over the next few weeks, I will rip out the existing board and install the guts from my DX6, and change the momentary trainer button on my 6102DX to a toggle switch so I can use it as a "hands off" Tx base station. While I 'm at it I'll hook some of the trigger/buttons to channels 5 & 6 for shutter/smoke/bombs/rockets/whoknowswhat

I'm thinking that this might be cool to try with a real time fly by video setup that I have used before.
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Jun 25, 2006, 08:42 PM
Registered User
Wow,

That seems really cool. Good Luck!
Jun 26, 2006, 03:48 PM
Volksflugen
Pelanconi Flyer's Avatar
Bad news for me. Looks like I may not be able to get replacement pots in 10K. The problem is that they are 40 degree effective rotation, and although CTS will make them for me in quantities of 1000 or more, they don't have them on the shelf somewhere. They are nice people though and they are checking to see if they have anything close in resistance/rotation.
Jun 26, 2006, 05:48 PM
"Simplify, then add lightness"
Don't know if you are into programming microcontrollers, but this would be a simple program for a PIC or AVR to read the existing pots into A/D inputs on the micro and output a PPM string to the buddy port. Not sure about JR, but on most Futaba and Hitec, you can even get the power off the buddy port, so you could build the micro into the base of the joystick, with just a cable to the buddy connector on the transmitter.
Jun 26, 2006, 08:56 PM
Registered User
Peteohms's Avatar
Take the sticks out of an old transmitter and fit them into a new housing. Easy money.
Jul 20, 2006, 10:20 PM
RC Bum
Eric_N57105's Avatar
Why not just parallel each of the 100K pots with an 11K resistor (a 10K and 1K in series, then paralleled across the end terminals)? That'll give you a 10K pot!

Eric
www.ke6us.com
Jul 22, 2006, 06:13 AM
supreme being of leisure
ZAGNUT's Avatar
Quote:
Originally Posted by Eric_N57105
Why not just parallel each of the 100K pots with an 11K resistor (a 10K and 1K in series, then paralleled across the end terminals)? That'll give you a 10K pot!

Eric
www.ke6us.com

but linearity will be way off



dave
Jul 22, 2006, 01:23 PM
RC Bum
Eric_N57105's Avatar
Quote:
Originally Posted by ZAGNUT
but linearity will be way off
dave
Very true. I forgot about that. It's already to 9K at 50%. Not too good.

Eric
www.ke6us.com
Jul 24, 2006, 02:14 PM
TP 1.21 Gigawatt Needed
MikeBiv's Avatar
Great Controller for a HomeBrew UAV system!
Jul 26, 2006, 10:45 PM
volare est vivere
ray foley's Avatar
What you really have to do is make up an analog interface board that takes the output of the pot wipers and conditions the voltage signal to match the voltage span of the pots in your xmtr at min, max positions. A simple op amp circuit with zero and span adjustments for each channel/axis can be made to simulate the operation.

and, oh yes, real men design in analog.

ciao -rjf
Aug 11, 2006, 05:19 AM
Registered User
dont pots get read in charging a fixed capacitor...timing how long it gets?
You could do a very simple PIC board that just goes high after a period, logarithmicly coupled to the pots you have.

Real men design digital

the opamp circuit might be way easier though
Aug 11, 2006, 05:21 AM
Registered User
Quote:
Originally Posted by jeffs555
Don't know if you are into programming microcontrollers, but this would be a simple program for a PIC or AVR to read the existing pots into A/D inputs on the micro and output a PPM string to the buddy port. Not sure about JR, but on most Futaba and Hitec, you can even get the power off the buddy port, so you could build the micro into the base of the joystick, with just a cable to the buddy connector on the transmitter.
easiest solution i guess if you have PIC stuff
Aug 12, 2006, 06:34 PM
dieselburner
andrew b's Avatar
Why do you need these pots? you could change the timing capacitor on PWM, it would have to be bigger. The PWM is a series of monostables with variable on/off time, a 555 for each channel should suffice, just select the capacitor on each 555 so that you achieve the correct stick span. First thing to investigate would be actually how much does the resistance of the pot change from one end of travel to the other. Have you thought how you would achieve trims?
Aug 12, 2006, 11:29 PM
Registered User
Most standard pots have about 300 degree rotation. If you paint about 130 degrees on each end of the resistive element with silver or copper print conductive paint you will have about a 13K pot with 40 degree rotation if you start with a 100K linear taper pot. Probably close enough for your application.


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