programming help

[Asimov]

How do model rail DCC decoders overcome the models motor inertia?

I have achieved it from a standing start by briefly pulsing the motor with a voltage sufficient to overcome the inertia prior to returning to a voltage that runs the model at a prototypical speed. This is barely noticeable from a standing start, but I can't figure out how to achieve a gradual start because the higher voltage required to get the motor started causes the model to surge forward momentarily.

 

[fgump]

Asimov,

If I understand your question correctly, I believe you may need to use a starting capacitor to assist you in getting your motor started. Perhaps this article on gradually starting a motor may help too.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCQQFjAA&url=http://forum.allaboutcircuits.com/showthread.php?t=44391&ei=aaYUU7ekO8Oz2QXzuoCYCw&usg=AFQjCNFGtAL72aubyc07uOv27yaLGo1HOg&bvm=bv.61965928,d.b2I

Best Regards

 

[Asimov]

Thanks for the reply, I'll look into that..,,

 

[Buzby]

I think you will find that a DCC decoder contains a processor to control the PWM to the motor. By monitoring the motor speed the PWM can be adjusted to give very smooth acceleration from zero.

Just try PICAXE PWM without motor speed feedback, you might find that works OK.

There are lots of entries in the Forum about PWM, and I'm sure you will get help from the members.

Cheers,

Buzby