QUOTE (Carnforth @ 26 Mar 2007, 12:52)
<{POST_SNAPBACK}>Thanks for that Pete
Looks like DCC is the way ahead. I'm still using H+M Duets and Mashima motors.Will these motors take DCC Ok? I understand that DCC uses wave switching and that this can damage some motors,am I correct here?
Cheers
Ste.
Re your original chassis question, you need to ensure is that both motor connections are fully isolated and that the decoder is isolated from the chassis. It matters not how the DCC is picked up, but the more current collectors, the better. Make sure your insulated wheels really are insulated from the live parts of the chassis at all times (e.g. on the tightest curves if any axles have sideplay). DC operation can hide a multitude of sins that can bite when you switch to DCC.
DCC decoders do use PWM (Pulse width modulation) to drive the motor. This applies full voltage to the motor in pulses. The motor speed is varied by changing the length of the pulses, the average of the on and off periods determining the speed. In the early days, decoders used a low pulse frequency (up to a few 100Hz) that could cause overheating in coreless motors such as Portescap. Most (if not all) current decoders use high frequency PWM (20KHz and above, there are various marketing names such as "ultrasonic" or "silent"). The inductance of the wiring and motor make these high frequency pulses appear more like DC to the motor so there is no danger to the motor. Mashima will be fine with old and new decoders.
In all cases, keep the track voltage just high enough to achieve the top speed of your fastest loco. Slower locos can have their response tailored in the decoder so that you can still drive them using the full throttle range.
Andrew