# NCE "Silent Running Motor Drive"?



## xrunner (Jul 29, 2011)

My Atlas has an NCE decoder. It says, among other things on the box, that the decoder implements a "Silent Running" motor drive.

What does that mean and how does it work?


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## tankist (Jun 11, 2009)

that means the PWM (power width modulation) pulse the decoder sends out is of very high frequency. this way you do not hear the PWM squeal during low speed operation, unlike in your cordless drill for example.


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## xrunner (Jul 29, 2011)

tankist said:


> that means the PWM (power width modulation) pulse the decoder sends out is of very high frequency. this way you do not hear the PWM squeal during low speed operation, unlike in your cordless drill for example.


OK. The name "Silent Drive" has a TM symbol by it on the box. That means they claim the name, but do other DCC vendors have "silent drive" also?


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## tankist (Jun 11, 2009)

digitrax calls them "supersonic". while the exact frequency may vary the idea is the same - PWM squeal is inaudible


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