Min-X Pulsemite with Contolaire actuator converted to 2.4 GHz

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mlbco
Posts: 10
Joined: 16 Feb 2021, 06:12

Min-X Pulsemite with Contolaire actuator converted to 2.4 GHz

Post by mlbco »

I converted a Min-X Pulsemite transmitter to 2.4 Ghz using an Arduino to read the stick potentiometers and push-button switches and then create a pulse train for an FrSky 2.4 module. A conventional 2.4 receiver sits inside the original Min-x receiver case and it drives another Arduino+H-bridge to control a Controlaire GG actuator for rudder, elevator, and throttle control. I wrote the code for both Arduinos and recreated all the functionality of the original GG system.

The radio is installed in a scratch built diesel powered (Redfin .030) model. I've flown this model many times and the radio works great. The videos below show it in action and the second video is from a camera mounted on the fuselage looking at the tail surfaces while flying.

Two things I didn't expect about the Min-X transmitter. First, it is really slippery with the smooth aluminum anodized case when your hands are covered in diesel fuel. Second, the bright gold anodizing reflects the sun so strongly that I have nearly blinded myself just picking up the transmitter. Sometimes it reflects off my glasses when I'm flying causing distractions. I never expected the transmitter case finish would be a problem until it was!

Steve

https://www.youtube.com/watch?v=YJwCMBM0m5k
https://www.youtube.com/watch?v=nf0_aBRMeQc
jmendoza
Posts: 133
Joined: 18 Feb 2018, 23:07

Re: Min-X Pulsemite with Contolaire actuator converted to 2.4 GHz

Post by jmendoza »

Nice!
I noticed you are flying it fairly fast, which I also had to do to get good control response. Using throttle mostly to control climb and descent seemed to work better for me than using elevator. The Controlaire "Ghost Mk II" actuator does give more throttle positions than the Rand, which only has 5 positions.
Did you have to replace the pinion gear on the actuator? The original plastic pinion gears I have were all cracked, so I used a brass gear salvaged from a Mitsumi servo motor.
When I converted a Pulsmite to 2.4, we removed all the components from the board as it held the joystick assembly.
The Min-X allows much more control stick and trim throw than other GG radios, as the first ones were set up for 80/20 pulse width shift.
Thanks for sharing your project, it was fun to see you flying the plane.
Jay
mlbco
Posts: 10
Joined: 16 Feb 2021, 06:12

Re: Min-X Pulsemite with Contolaire actuator converted to 2.4 GHz

Post by mlbco »

Jay,
My Controlaire actuator didn't need any modifications, it has been working OK in the configuration I purchased on eBay. It looks like the pinion is brass, maybe that was an upgrade from the factory?

I gutted the Min-X transmitter and wired the potentiometers and switch to an Arduino. The Arduino reads all the inputs and then generates the pulse train required by the 2.4GHz FrSky module. On the airplane side, a standard 2.4GHz receiver feeds PWM inputs to another Arduino that turns these into the appropriate on/off motor pulses for the actuator. I wrote all the code and was able to set up the max pulse on/off ratios and frequency range to suit my tastes. I have another GG model, a Top Flite Schoolgirl, with an original Controlaire GG radio on 27MHz and a Rand LR3 actuator. That unit has a slower pulse rate and the model visibly "gallops" in flight. I linked the video below.

The model is small for this equipment, it was originally designed for pulse actuator R-O flying and the GG installation added more weight, so it does fly fast. It only has about 1 sq-ft wing area.

Thanks,

Steve
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