TTS sound on n-guage - aligning chuff to speed

[Waddy7]

I have fitted a TTS chip to a Graham Farrish Castle class loco, and am generally very pleased with the performance.  However the chuff sounds are out of synchronisation with the wheel speeds, and there doesn't appear to be a way of setting the maximum speed of the loco - it goes far too fast at maximum speed.  If I slowly increase the throttle it is better, and programming the acceleration CV from default of 15 to 45 has helped, but there must be a better way of slowing down the maximum speed and improving the synchronisation?  Does anyone know how the CV 151 and 152 factors work?  I can't seem to find a full explanation on the Hornby website and the decoder manual states the explanation is beyond the scope of the leaflet.

[Chrissaf]

Use the forum 'Search by Post Content" and do two searches. One for CV151 and one for CV 151 you will get lots of hits.

[jane1707819582]

hi waddy 

there is no chuff synchronisation on the tts decoder .

there  is no cv supportable on the tts for maximum voltage either .

cv 151 and 152 controls the motor and how it feeds back to the decoder, if your loco is jerking when setting off or jerking when it is coming to a stop then alter cv 151 and 152 up and down by a value of 5 until you get smooth running .

by entering cv 150 to 1,this switches control over to cv 153 and cv 154 ,you may improve the smooth running of your loco ,but not the max speed .

[2e0dtoeric]

Chuff to R.P.M's - standing complaint about TTS. On diesels, you can't see the error, but on a steam outline - it glares. (Yes, I know diesels don't chuff!)

[Waddy7]

Thanks for your replies, especially Jane2, very helpful to know there is no scaling factor that can be applied, which is a pity. 

I had tried changing the CV 150, 151 and 152 before posting my question, but with little difference visible - loco runs smoothly enough and increasing CV 3 certainly helps make the chuffs more realistic.  I would still like to understand how the motor control CVs are supposed to work (I know and can see the difference between non-linear - CV 150 = 0 - and linear =1) and that the higher values of CV 151 and 152 make the motor control "stronger?" but haven't found an article on the theory anywhere yet (maybe a Hornby trade secret?).

Thanks for your help anyway

[96RAF]

Its not a Hornby secret it is simply applying PID motor control. There is a wealth of info on the interweb about it but very little that tells you in a simple step by step method of how to apply it to a DCC decoder.

 

On other forums folk have made some effort and produced a viable guide to the effect of the two pairs of CVs (151 and 152 or 153 and 154) that we are able to alter for each main motor control regime (CV150  = 0 or 1). In effect you are altering the way the motor responds either on accelleration or decelleration to find the smoothest curve either linear or complex. Knocking off bemf can also affect motor smoothness but it essential to have this enabled on TTS steam locos as this controls whether chuff is on or it is coasting - load dependant and during accel/decell from the throttle.

Rob

[jane1707819582]

Thanks for your replies, especially Jane2, very helpful to know there is no scaling factor that can be applied, which is a pity. 

I had tried changing the CV 150, 151 and 152 before posting my question, but with little difference visible - loco runs smoothly enough and increasing CV 3 certainly helps make the chuffs more realistic.  I would still like to understand how the motor control CVs are supposed to work (I know and can see the difference between non-linear - CV 150 = 0 - and linear =1) and that the higher values of CV 151 and 152 make the motor control "stronger?" but haven't found an article on the theory anywhere yet (maybe a Hornby trade secret?).

Thanks for your help anyway

when you change cv 150 to 1 cv 151 and cv 152 are not used cv 153 and 154 come into play 

the respective cv's represent pid control so when you supply the dc voltage to the motor, the motor feeds back a voltage to the decoder as you accelerate the decoder supplies as a pulse to the motor this speeds up the motor .hence the back emf also increases now the decoder using its pid (cv 151 etc )decides what speed the motor should be going and either decreases it's pulse or increases if it "thinks" it is too slow it will increase ,too fast it will decrease if you have to high a value in the cv it will increase/ decrease accordingly and will jerk the motor when accelerating and similar when slowing down ,does that help?

this is how i understand it 

if we now transfer to pid to temprature control  if you want to heat a pan of water to 90 degrees and the water is 5 degrees you want full power to begin heating as you approach 90 degrees say 80 you can reduce the power supplied this will begin to help control the heat and prevent it over shooting 90 ,and as you further approach 90 you reduce power further still until you match the power with the temprature. if you were to just switch off the power at 90 then any latent heat in your element would push the temprature higher than needed.

hopefully this helps you waddy