Finally got my control system tested out in the woods. Very happy with the range. The Xbee will do 300ft and I can’t even see the RS3 if I go that far away. This is my design. All the wireless communications are handled by the Xbee. I can send any sort of data to or from anything with this system in real time. Those are 16 byte data packets that are controlling the throttle and coupler servos.

The RS3 has the throttle, front and rear couplers and single channel sound all hooked up and working. All of it is powered by a 5000mah hour LiPoly battery driving a Pololu 18v7 motor controller. The control widget drives the servos directly. There is also an RFID reader under the fuel tank which works quite well too.

As cooler weather approaches, I will be getting back to s/w development on my Xbee control system and doing some more character modeling for 3D printing. The Xbee stuff works quite well, however there are only hooks in for the configurable portions. The Attiny 1634 processor has 256 bytes of eeprom for non-volatile storage, I want to leverage the code into getting the various control limits and settings from this instead of hard-coding everything per device. I will also implement a new network message to program the client devices via a web page interface, this should make setup and tweaking of each device much more user friendly.

As for the 3D character modeling, I have found a potent set of freeware tools that I am currently working through the learning curve on. In particular Blender has a somewhat non-standard interface but once you get the hang of it, not too bad. (see various posts below for more reading on this). It has some really neat options too, including cloth physics (draping clothes over 3D people, etc) and can also load bvh motion capture files to apply animations to your creations. While I don’t specifically use animations for my 3D printing, selecting a single frame as a basis for a pose is quite handy. Make Human is the other freeware package, it’s learning curve is actually quite small. You just move a set of sliders to create human 3D mesh objects, you can select gender, age, weight, height, etc, quite cool.

Another hobby/business that is coming along well is the airplane. One Seven Two Mike Echo now sports a newly overhauled 320-E2D engine with new mags, a startek starter and the 160hp STC upgrade. She really flies great now, MUCH noticed improvement in performance and a few more knots in cruise. Really sweet. I’m looking forward to more adventures.Now she just needs to rent rent rent so I can pay for all that! ha.

I am also trying to finish up the first section of my outdoor train layout, I have the frame built and am currently experimenting with concrete scenery shell techniques (ala Disney magic mountain) and it’s coming along nicely. I don’t have much time left before the cold will become too much to cure the concrete (actually sand/topping finish mix) so I’m putting most of my effort there. My plan is to get the basic scenery shell done and lay the track into the ballast so I can do some research on how the whole thing survives the winter. Ah, engineering, I do love it so!


I realized I didn’t have this posted up- this is the single channel mp3 sound card from combined with a simple audio amp. The amp is quite loud and can be built with parts from Radio Shack. This is what I’m using on my RS3 in the pictures below. I’m using the Attiny 1634 s/w UART to drive this from the client widget. It works quite well, you just send a single byte to the card to set the volume or play one of the sounds. However, you get what you pay for, $10 only gets you one sound at a time.




Here are a couple of shots of my control system going into my Aristocraft RS3. The power is all in the back end, I have a 5000mah 14.8v lipo pack driving this beast with a Pololu 18v7 motor controller powering the trucks. A very potent drive train. Anyhow, these pics show the brains- the Atmel 1634 board, the Xbee Series 1 and the MDFly mp3 sound card. Not seen is the RFID reader on the fuel tank- I’ll post that up later. Phew, some work and lots of engineering spits and fails but it’s now pretty clean and works well. I did downsize the controls a bit, I’m only driving the motor, the two coupler servos and the sound card. I left the lights on a manual switch and there is a current sensor in there but I’m not looking at it right now. As mentioned, the RFID is also connected and works so I do have the basics of a computer controlled system. The main control boards are also reasonably accessable by taking off just the short hood of the locomotive so tweaking the firmware, sounds and the pololu motor controller won’t require the entire locomotive to be taken apart (which is a BITCH to say the least!)


Finally have all of the connections wired and (more or less) tested. I’ve added LEDs to the running lights and servos (not shown) to control the couplers. Just need to add about 11oz or so to the fuel tank and put it all back together for final testing. I’ve attached a programming cable to the microcontroller board so I can download new builds or tweak the s/w if required. Phew. This has been quite a bit of development. The control widget itself went through many interations (see as did the power board. I’ve settled on the Pololu 18v7 programmed to only give forward motion with a relay switching between forward and backward. Anyhow, soon we will be doing some real world testing.


Here is my latest stand-alone hand-held-throttle design. It’s based on my control widget thing and I (finally) have it all working.

All the circuits and keyboard are mounted on a 3D printed faceplate with a 3D printed back enclosure. It still needs some structural work, screws to hold the face plate on and I need to mount the power switch too, not sure where that should go.

There is some hard-coded stuff in the handheld software but it does work quite well. I also have a slight design gotcha on my USB interface into this thing but I’ll get that solved soon.


I’m really enjoying my widget PCB design. Simple, cheap, easy bake oven for SOIC, program in C, add an Xbee for wireless real-time control, how cool is that? Here I have one hooked up to a parallax IR motion sensor. With a bit of C code it controls the servo based on the input from the motion sensor. Think railroad crossing signals- that crossing arm that comes dowm and blocks the traffic, right?

Anyhow, great fun and a good project to post over to

I’m looking at a $9 retail for board and components. Software will be free and open source. Of course :)