Spectrum snd/dcc equipped 4-6-0

[Ozzie21]

it's not linked to throttle position but to motor load. Change the load on the motor and the chuff rate will change slightly as will the timbre of the exhaust. While the the Tsnumai OEM is laid out differently to a Tsnuami all the Cv's are the same except for whistle which has only 3 selections instead of the normal 7. By tuning the decoder CV's 2,3,4,5,6, 116,209 and 210, whose default settings are a compromise to allow the loco to run. By further tuning these CV's the running qualites will be improved.

Charles Emerson

Queensland
Australia

If you can alter CVs, you can alter the chuff rate.
Gene

That's true.

But unfortunately, the OEM Tsunami's chuff rate is linked to the throttle & not the anything the loco is doing.
I have corrected the chuff on several Tsunami OEM locos, but as soon as you apply any load [incline or cars]; or remove any load [decline] the throttle position is changed & therefore the chuff is running at a different rate.

So I guess, if you get rid of all that boring stuff like freight & passenger cars, shunting, inclines etc - I mean, what's wrong with running your Tsunami OEM loco light, on a billiard table smooth flat surface?.......?

[Mark Damien]

it's not linked to throttle position but to motor load. Change the load on the motor and the chuff rate will change slightly as will the timbre of the exhaust. While the the Tsnumai OEM is laid out differently to a Tsnuami all the Cv's are the same except for whistle which has only 3 selections instead of the normal 7. By tuning the decoder CV's 2,3,4,5,6, 116,209 and 210, whose default settings are a compromise to allow the loco to run. By further tuning these CV's the running qualites will be improved.

G'day Charles,

I'll have to disagree with you on one point. CV 116; the Auto Exhaust Rate, is not controlled or related to any Bemf signal. If that is the case you cannot attain a sychronised Chuff Rate across the speed range.  CV 116 is  linearly proportional to throttle setting. You can apply a Speed Table, CV25, but this again is only an approximation & not connected with any Bemf input.

[Ozzie21]

Mark, this is quite true but as I said it is prportional to motor load based on voltage and yes if you tune a few more Cv's that I haven't mentioned you can get the chuff closer still. You cannot get it to be exact by using this form of electronic method. I generally use some form of cam be it electro mechanical or optical. On the Bachmann locos this can be done b by fitting an axle mounted cam or a wheel mounted cam. Other ways that are slightly more complex is by using an optical sensor or magnetic reed switch. These methods require more ingeniuity on the behalf of the modeller as in most cases extra space as to found as well as magnets for the backs of wheels to provide the magnetic influence for a reed switch.
The axle mounted cam is the easier method but due to Bachmann's insulated wheels and small diameter axles it makes it slightly more difficult to mount. The easiest method, if slightly unsightly is to use a disc mounted cam similar to the Soundtraxx cams These can be glued to the back of the wheel. An electircal path has to be provided and some form of pickup mounted. This can all be done quite quickly and you can a synchronised chuff in afternoon.


Charles Emerson
Queensland
Australia

it's not linked to throttle position but to motor load. Change the load on the motor and the chuff rate will change slightly as will the timbre of the exhaust. While the the Tsnumai OEM is laid out differently to a Tsnuami all the Cv's are the same except for whistle which has only 3 selections instead of the normal 7. By tuning the decoder CV's 2,3,4,5,6, 116,209 and 210, whose default settings are a compromise to allow the loco to run. By further tuning these CV's the running qualites will be improved.

G'day Charles,

I'll have to disagree with you on one point. CV 116; the Auto Exhaust Rate, is not controlled or related to any Bemf signal. If that is the case you cannot attain a sychronised Chuff Rate across the speed range.  CV 116 is  linearly proportional to throttle setting. You can apply a Speed Table, CV25, but this again is only an approximation & not connected with any Bemf input.

[Mark Damien]

G'Day Charles,

That's all good advise & would certainly go a long way to attaining sychronisation.

I do think it unfortunate that Soundtraxx could perform a relatively simple rewrite of the Tsunami firmwear, & the Bemf signal could be made available for the Auto Exhaust to use, solving the problem for everyone.

To take the ball to the try line, but not step over & score, always seems odd to me.