Model Railway Forum banner
1 - 3 of 18 Posts

· Registered
2,342 Posts
Hi Sennapod

Top speed is not governed by the power rating of the decoder - the 1 Amp rating is the maximum permissible power it can handle.

The speed of the locomotive is governed by the DCC track voltage and the the decoder settings for motor control. If the decoder is still at the factory default settings the top speed will be the maximum available . If the track voltage is 14v then the motor will receive about 13v. The Old DC controllers can sometimes put out around 17v giving a greater top speed.

The Motor receives pulses of power from the decoder , so the power is not on 100% of the time , at top speed it may have power on for 90% of the time . decoders with Back EMF detect voltage when the motor power has been switched off.The motor acts as a generator when no power is applied , then the decoder can measure this for motor control
This is an over simplification to what actually happens though

Some motors do run better than others under DCC control , Some of my older Fleischmann loco's are the same -only running at about 60% of the top speed that they would on DC (my DCC track voltage is about 14.5v) they did run the same as the old DC controller when the DCC track voltage was 20v with my bad old Roco power Supply - but that caused other problems - internal lighting in coaches very bright etc.

But even at 60% of the old top speed they are running faster than the scale speed of the real locomotive


1 - 3 of 18 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.