New CTEC Keycoder

I think I’m almost done with my new keycoder, it’s gone thru several iterations and I’ve ironed out most of the bugs.

I’d posted earlier this week that I’d started with a box I made out of aluminum angle, and added a bunch of momentary toggle switches, I then took the guts out of two RF remotes and wired them up inside. Sounds easy but it didn’t feel like it at the time.

The switches are mini (on)-off-(on) momentary, I really wanted to try and get sub-mini’s that just did (on)-off, but I couldn’t find any at a price I was willing to pay. I think the switches I ended up with worked out to be around a $1 each after shipping.

Space is very tight and I really didn’t want to make the box any bigger than absolutely necessary, so I ended up trimming the RF boards down and consolidating the antennas as well as removing the two batteries.

The switches center solder tabs are common and wired together

This is the spaghetti I’d created once I was “done” wiring the switches in

With being generous with the wire I’d forgotten it all had to fit in the box somehow! So I ended up shortening everything down. I also wrapped the backs of the switches and any critical parts of the boards in electrical tape.

I’d tried really hard to fit rechargeable batteries inside too, but ended up with a better solution I think. I ran a cable out and up into the battery compartment of the Futaba to share it’s battery. The cable has a Y split in it for easy removal. The RF remotes come with a 12V battery, but I’ve tested and found that they work very happily on the 10VDC coming from the Futaba. When I double checked my older remotes their batteries had dropped to 6V and were still working fine.

So, that’s my new CTEC keycoder almost done.


  • Having the antenna internally limits range so I’ll be moving it outside.
  • Total cost was roughly $94 (incl. two RF setups $60, aluminum $10, switches $24), and about 2 or 3 days of work. On the other hand the Vantec Hitchiker product is around $450 – and only works with their special Futaba 75Mhz FM 9CAP, but does have some great features that I will need a cheap micro-controller to replicate.
  • My keycoder weights in at 10oz, adding to the already heavy Futaba setup at almost 2.5lb. So I may look into making a plastic box – but the weight of the switches definitely adds up.

One last trick I learned is that you can have multiple remotes control a single RF receiver. Yep, you heard that right. I’ve been controlling multiple RF receivers with one remote for a while, but had no idea it would work the other way around – each remote doesn’t not need to have the same code even. I accidentally found this out while trying to mate the new keycoders remotes to my droid and found that my older remotes still worked.


Posted by Chris on August 6th, 2008 in Electronics | 3 Comments

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Mystery Box

Anyone want to hazard a guess what I’m trying to make here?

This photo should give it away

More photos in a few days

Posted by Chris on August 2nd, 2008 in Electronics | 5 Comments

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Mist / Fire Extinguisher Test

Well I’m back working on R2. It’s been a while since I’ve done anything on him and I’ve still got a long list of big to-do’s. Sadly, instead of working on the small things I’ve been avoiding everything.

Inspired by reading Victors success with the Mist/Fire Extinguisher effect this week I decided I’d give it a go this weekend, hoping it would kick start me going back to work on more difficult things like the skins.

The mist is created by an inverted can of compress air normally used to dust PC’s and office equipment. When it’s inverted rather than spray air, a watery/icy mist comes out.

I decided to put the air cannister and output in the dome instead of the body. I really liked the idea of popping open a dome hatch/side panel and having something come out, and I thought this would be perfect.

I’d already bought a cheap solenoid which was part of a trunk release kit I found on eBay. I had looked locally, but eBay seemed to be cheaper. Wiring it in was a snap and it’s only a few wires. It’s triggered with a spare channel on my RF remote.

I cut a 1 1/2″ acrylic strip and bent it into an L shape. I bolted it to the Dome Mounting Ring and then used clamps to hold the cannister and solenoid to it.

I drilled a small hole in the trigger of the air cannister and connected it to the solenoid with a bend paper clip.

Here’s a rough diagram of how it’s wired

Space in the dome is tight and I’m sure I’ll need to move things around or lower/angle the cannister more to accommodate the periscope lift mech.

Here a short movie clip of the first test with the dome off

Then with the dome on

I still need to add a hinge to the hatch and power it with a servo. I did tinker a bit with the Robart hinges but decided to leave this for tomorrow.

Posted by Chris on August 4th, 2007 in Dome, Electronics | 1 Comment

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