DCC sound with Analogue DC Control

[andybuttterworth1962]

Hi

 

I am hooked on the idea off DCC and sound. But.....

 

With some 25 loco's to convert it will prove extremely costly and therefore a potential non starter.

 

However, on reading up about the ESU Loksound V4 decoder, it states quite clearly that it has a analogue mode enabling it to be operated on a DC ananlogue system. I cannot think how this is possible. A loco 'parked' on an isolating section, is exactly that - Isolated, without power and effectively dead.

 

So - How does it work? - I assume only when the loco is actually running - but how are the sounds triggered - such as engine start/stop?

 

Please can someone enlighten me - or better still has someone tried it? is it feasible

 

Cheers

[Phil S]

Quite simple: Consider the different scenarios:

As with dcc, if no power, no sound. [ unless backup-battieries are included, as is an option with LGB garden railways, in analogue ... maybe having a bit more space ]

 

With dcc, when power is present, it is at full voltage: the controller  may or may not be 'cycling through' the number of the loco - it is likely to remain silent in dcc until the loco is 'called up' on a controller.  [ therefore it may or may not restart after an emergency stop is removed ... depending on how many locos are 'in use' ]

How long this active cycle is depends on the controller - and could be as few as 8, or as many as 64 in my experience. [LGB MTS = 8, RocoCentralePro = 64]

 

Whether 'standing sounds' are on or off can be both a CV setting (including their volume) or may ALSO await the loco being called (eg Digitrax)

The dynamic sound etc is then, of course, simply refelcting the requested speed code being sent, as modified by any back-emf measurement.

 

With analogue: as with 'silent decoder' operation, first the track voltage must rise to eg 5V to turn on the microprocessor. Then the Decoder makes an assessment of the analoguer voltage, and interprets into a speed request: so eg 5.1V = stationary through to 16V = full speed  [ Note thatt he decoder won't actually know what the 'maximum' will be, except is should not exceed approx 22V ]

 

A SOUND DECODER typically 'modifies' this 'linear' relationship of voltage to speed, by including time-dealays in the response: in dcc, the HST start up sound can last 30+ seconds before the loco is allowed to move !! (regardless of what you do with the throttle in that time)

So a 'preset' sequence of soundfiles are played out, triggered by differing voltages (in analogue) corresponding to requested speed changes .... the start up bell, the engine turning over and bursting into life, and then beginnning to run smoothly at normal temperatures etc.

Depending on the 'quality' of the sound decoder and its sound files, as to how complete a (sound) picture is created - in dcc or analogue modes.

Note - if sound was Muted in digital mode, then it is likley to remain muted in analogue !

 

For best results, on analogue, increase the control-throttle SLOWLY as it reaches the turn-on point, and similarly reduce it only to that posiiton - the sound of a stationary loco can then continue ... with about 5V on track, but none of it being sent to the motor.

[andybuttterworth1962]

thanks Pete, think I understand the answer

I guess it's a case of tuning the device to 'turn-on' without the motor turning - but that implies a dcc controller.

 

It certainly seems a 'halfway house' solution - at the end of the day an isolated loco cannot possibly sit there and 'tick-over' at idle! and the whole point would be sound from at least 3 or 4 loco's simultaneously.

 

Going full dcc would seem the only solution that will be ultimately satisfactory  -  and reconvert to sound as funding permits.

 

Having been inspired by the Oak Hill TMD layout (Sutton MRC), I think I'll just  have to just bite the bullet!

[Phil S]

Phil; No it does not imply a dcc controller !! - that would never produce the steady analogue voltage needed to power the microprocessor, but remain low enough not to be interpreted as a request to drive the loco.  IT DOES REQUIRE A SMOOTH_OUTPUT analogue controller.

 

This method has been used widely for many years with G-Scale locos ... because they have been sold with sound and digital DCC control for many years, but many garden operators, especially those with albeit-large 'simple loop' layouts around their garden, still operate them with analogue controllers - track magnets adding the 'spot effects' such as whistles and horns.

 

If you are 'still analogue', but want several locos idling in sidings, then perhaps a separate  supply; 'the idle controller', is called for:  There are some useful variable voltage regulators available on Ebay for a few pounds, which could take (for example) a 9V wall-wart power supply input, and reduce it to just the level which starts the sounds .... however they might all have to be the same make and version of sound decoder, or they may start at different voltages.

 

Going back in time, 'Argo' recording and BBC sound effects records can be chosen to play back 'generic' atmospheric sound without specifically tieing it to a particular loco.

To localise the effect, you could use a 'Point-of-sale' device: as used in some shops.... when you are detected in  front of them, the sound plays back ... so if you stood infront of your goods yard, it would play 'goods yard effects', or in front of a beachside station, it could play back the sound of waves.

 

(At a Narrow-Gauge exhibition in the Nederlands a few years ago we watched/listened to a small H0e layout which had 7 or more speakers to convey a very convincing sound picture - without any speaker within a locomotive... and a very good large bass speaker.  Alternative methods are always available.

 

Of course, yes the ultimate solution is to go DCC, and the best time for that is when starting to build the layout, otherwise it can end up as the worst of analogue and digital wiring!

There are some sound decoders which are much cheaper than the ESU/Zimo examples, which tend to have simpler programming..... I have gone over to using Digitrax SDH164's for DMUs (a class 108 sound is available) ...because it is such a characteristic of DMUs to be left idling in stations for a long time, and its less than 40GBP each including basic speaker.

 

PS - who was 'Pete' ???

[andybuttterworth1962]

dunno who Pete was!

 

thanks for the info