How to use the Spektrum 2.4 GHz radio control system

This page is about the Spektrum remote control system, and how to apply it to robots: in my case, antweight robots, although I’m sure most of this applies to other weight categories.

Introducing the Spektrum

The basic difference between the Spektrum remote control system and all the rest (at the moment) is that it doesn’t use crystals. Without getting too technical it adds information to the signal to make sure that there will be no interference between transmitters. Here are some advantages

  • You don’t need to build up a collection of crystals in order to compete
  • You don’t need to worry about transmitter control at an event
  • You can go to any model show, and not have to stick to a narrow band range
  • It uses a much higher frequency of signal, so no need to supress motor noise
  • NO INTERFERENCE!

The only disadvantage that I can see is that the Spektrum is more expensive, but possibly worth the money. Remember to try ebay before buying from a regular shop. There are some good deals out there.

Some pictures

The Spektrum DX6 transmitter
On the left, a Futaba R114F receiver, stripped of its casing but with crystal: weighing 8.8g. On the right, a Spektrum AR6000 receiver, stripped of its case, a tiddly 5.3g.
The AR6000 receiver in situ (in fact in Dynamold)
Dynamold with the AR6000 at the bottom

Using the system

The AR6000, which is a 6 channel receiver, assigns aircraft type names to the channels. In the days of Futaba, I would connect channels 1 and 2 to right and left and use up-diagonal-right to make the robot go forward. This doesn’t work on the Spektrum. Instead, I use channel 2 (marked AILE on the receiver) for left and channel 3 (ELE) for the right wheel.

I then reverse the direction of the servos (page 38 of the manual) and can use up-diagonal-right as before. If I wanted to use up for forward instead, then I would keep the servos on their normal setting and turn on the delta wing function (page 33 of (the manual).

The schematic above shows the two switches and two joysticks, and which channels they control.

Plugging in

The Futaba R114F, and most other FM receivers have their servo plugs at the side. The Spektrum AR6000 has them at the top, this means that it’s trickier to fit into a low space.

I decided to get around this problem by soldering the connections from the Sozbots motor controller board to the receiver. I soldered the underside of the receiver board because there is already solder there, and because I could imagine the wires getting short circuited amongst all the pins at the top of the receiver. Also, I might want to plug things into the top of the receiver someday.

Where to solder
The view from the back
A closeup of the back
The view from the top

 

The diagram above shows which points I connected. An interesting point about receivers is that they share one common connection between all the bottom-black-negative pins and another between all the middle-white-positive pins.

Knowing this enables you to get away with two fewer wires. Just run one positive wire from the Sozbots board (these boards share power between the left and right hand sides, unless you decide to cut them in half) and attach them to the two middle pins on sockets 2 and 3. Do a similar job with the bottom pins on sockets 2 and 3 and the negative wire. Then connect the left hand side of the Sozbots controller to socket 2 of the receiver, and the right side of the controller to socket 3 of the receiver.

This technique worked well for me, and also saved some weight.

And finally

This is a work in progress, if you have any comments then please comment at The Robot Wars 101 site.

disclaimer: I hope that this site is useful to you. Do take care when using tools and use the proper safety equipment. Remember that taking apart electrical components can be dangerous, to yourself and to them!

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