Friday, March 2, 2012

One step at a time

After a little discussion on Railpage in regards to driving turntables with stepper motors, I decided to sift through my box of junk and come up with half a solution. I only do things by halves, that's what my missus says anyway. The stepper motor controller is programmed using the PC and once the commands are downloaded onto the controllers EEPROM it runs independently. So far, to make the turntable rotate 180 degrees and back takes around 25 commands. Using 2279 steps to rotate through the 180 degrees means it has a fidelity of around 0.08 degrees per step. I have included a video with this post and you may notice that on the bridges return trip it actually runs back past the track and then forward into position. This has been done to take up any slack in the mechanism. I still want to add a calibrating move when power is applied.

Here is the video of my half built sellers 60ft turntable. The stepper makes some weird noises due to its pulsed type drive. I will try and soft mount the motor in the future but even now is a lot quieter than a gear reduced conventional motor. Every thing is sought of held together with blue tack but all stayed together for this demo.




There is some scope for this set up to be used with multi track turntable setups. Obviously it just becomes a lot more complicated programming all the different moves.

FS BS Cars

Work still continues on the Austrains FS BS cars. I have installed the super capacitor onto the lighting PCB simply by drilling two small holes, sticking the cap through and then soldering the zener onto the other side. This holds it all together. I still have to add the wires connecting it all to the output of the bridge rectifier. The super capacitor sits very neatly up in the ceiling of the door way area.

I have added a little extra detail to the under floors and the coupler position has been fixed resulting in the working diaphragms, well working!





Layout

No progress. It’s been too wet and I am still waiting on more PVC sheeting for the back scenes.

That’s it for now,

Linton