Nick_ Posted May 2, 2016 Share Posted May 2, 2016 Assuming the decoder CVs 5&6 are left set to their default values then speed step 127 equates to full voltage (12v ish). Some Hornby locos have been geared so that their top speed pretty much matches their true scale speed. The 42xx heavy tanks are an example of this where at maximum speed they are doing a scale 45mph, other locos are geared so at full power they can be doing a scale 200+ mph, the older small 0-4-0s are a goo example of this Link to comment Share on other sites More sharing options...
poliss Posted May 2, 2016 Share Posted May 2, 2016 A DCC decoder always sends the full 12 volts to the decoder. It's the amount of 12 volt pulses that determines speed. Link to comment Share on other sites More sharing options...
Nick_ Posted May 2, 2016 Share Posted May 2, 2016 A DCC decoder always sends the full 12 volts to the decoder. It's the amount of 12 volt pulses that determines speed.You're right, what I was really trying to say is that at speed step 127 and assuming CV5=0 (the default) then the motor will be getting enough pulses to generate the equivalent of the full 12v DC Link to comment Share on other sites More sharing options...
poliss Posted May 2, 2016 Share Posted May 2, 2016 *presses like button* Link to comment Share on other sites More sharing options...
Fishmanoz Posted May 2, 2016 Share Posted May 2, 2016 Just to be accurate, the number of pulses going to the motor doesn't change, they are always at the DCC frequency. What changes is their mark-space ratio which varies the averaged DC voltage to the motor between + and -12V or so by pulse width modulation of the DCC signal dependent on the speed step and direction sent to the decoder. Link to comment Share on other sites More sharing options...
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