what kind of RC controller / transmitter should I buy?

I have been going through David Covarrubias' tutorial on making a 3D printed animatronic eyeball mechanism and am looking for a controller. The tutorial suggests a Futaba 12 zap, which I believe is a controller with 12 channels. I found this futaba product with 14 channels: 

http://www.futabarc.com/systems/futk9410-14sg/

That controller is $550, so I'm looking around for something cheaper that will suit my needs, as this is my first hardcore animatronic endeavor.

I stumbled upon this Crazepony Radiolink transmitter on Amazon:

https://www.amazon.com/gp/product/B01FLWRY9Q/ref=ox_sc_act_title_3?ie=UTF8&psc=1&smid=A2SDALXLSH2BTX

It's a lot cheaper, at $55, but that price seems too good to be true. It's only 8 channels, compared with the futaba's 14, but it also doesn't seem to have a screen, which makes me think you can't do that much with it.

One feature I know I'd like is the ability to do channel mixing, like Covarrubias does in the tutorial. I can't tell if the Crazepony Radiolink has that feature. 

Another thought I have is that I'm going to be really close to my animatronic creatures, for the most part, compared to how far away RC cars and aircraft get from their controllers. So maybe one feature of higher end controllers is that long distance capability, which I don't really need (I think). 

One more thought is on interference - interference between my RC transmitter and other departments on set of any films I put my animatronic creatures in. Do I need to worry about ending up with a controller that operates at the same frequency as the microphones used by a sound mixer on set? If so, can anybody offer a way to avoid this? 

Any thoughts on any of this would be much appreciated. I'm also interested if anyone can suggest a good controller for animatronics. 

One final question is this: do I actually need a radio transmitter, or can I control my animatronic creature with wired controls? For example, I have two of these Servo Driver Pros ( http://www.rcdude.com/product-p/mx8340.htm ). Can anyone offer pros and cons to using a wired controller like this vs a radio transmitter? I guess one big obvious difference is with a radio transmitter you don't have to worry about hiding the wires connecting the creature to the controller in whatever shot you're setting up. And I don't think I could channel mix with the Servo Driver Pros. But maybe there's something between the servo driver pro and a radio transmitter? 

Thank you very much for any and all thoughts. 

Sincerely, 

Ben Gojer

Comments

  • Here's another question: How many channels should I aim for in a controller, and what's the point of having a lot of channels?

    These controllers seem to have two big joysticks. In the Covarrubias eye mechanism tutorial, he seems to have one joystick controlling two servos - the up/down motion controls one servo, and the left/right motion controls another. So if one joystick can control two servos, then I can see how you could control four servos at a time with the two joysticks on the controller. Then I guess if you have some channel mixing involved, maybe you could be controlling a couple more servos. But what is the point of having an 8, 10, 12, or 14 channel transmitter? Can you ever control that many servos at once with one controller?

    Or are you quickly switching between channels? Making the eye lids blink, then switching over to some other channels and raising the character's right arm and opening their fingers, then closing the fingers on a cookie and raising the arm to the character's mouth, then quickly switching over to the channel for the mouth and opening it, then switching back to the arms and fingers and placing the cookie in the mouth, then switching back to the mouth and chewing the cookie? Or am I missing something? 

    Thank you, 

    BenG
  • Okay, after a few hours of research, I'm thinking seriously about getting this Radiolink AT10: http://www.rcgroups.com/forums/showthread.php?t=2066015

    I found a pdf of the manual, which I attached here, and on page 53 it talks about doing channel mixes, so I'm feeling confident that I can do the channel mixing that Covarrubias talks about in his tutorial. I'm still interested to see if I can get any feedback from my post before committing to the investment. 

    Side note on the Covarrubias tutorial - I have been having a hard time discerning what exact materials I need for the post-3D print build, and then finding those exact materials. Yesterday I went to a hobby store and got a range of ball linkage parts and am going to experiment with them once I have my parts printed. I am also not using the exact servos Covarrubias recommends and will see how that goes. 
  • Chris EllerbyChris Ellerby Los Angeles Admin
    Hi Ben,

    Basically all you need is any spread spectrum controller with enough channels for your project and the ability to mix channels.  Beyond that, brand and extra features are up to your own desires/budget.

    My biggest suggestion is to look at user reviews for any transmitter you are interested in.

    Having lots of channels is useful if you plan on adding more servos to your character, or using those channels to control other things.  Full characters with moving lips, brows, nose, eyes, lids, head, etc. can quickly use up a lot of channels on a single controller.  But often you'll want to break the performance down to multiple controllers as one puppeteer can only handle so much.

    And if you are interested in programming and designing your own controllers you can do so fairly easily with Arduinos and an XBee transmitter/receiver.  But that is a bit more advanced if you are just starting out.

    To answer your "do I even need a transmitter" question, the answer is no (depending on your application).  Without a transmitter your character will be tethered.  If it's a stationary character that might be fine.  Also keep in mind that the length of the tether determines how far away your puppeteer(s) can be.  If you design a tethered character I suggest having your control cables be easy to swap so you can use longer/shorter cables as needed.  You can use any number of cable/connector standards XLR, CAT5, etc. There are many types of multi-pin connectors and cables out there.

    If it's a mobile character, tethers can still work, but they may impact performance.  Start with a list of the performance needs of your character (range, mobility, environment, stunts, etc) and base your system around that.

    As far as interfering with audio equipment, that is a possibility.  There are a lot of wireless devices operating on the 2.4 GHz band.  Here is a quick article on that:  http://www.eetimes.com/document.asp?doc_id=1273359

    I've never had issues with my transmitters around wireless lav mics or other audio gear, but your milage may vary.  It's worth discussing/testing with your sound guy, especially if they plan on doing something exotic that may increase the potential for conflict.

    /Chris



  • Thank you Chris!
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