DCC & analogue sound

ebay mike

ebay mike

Retired, but still hoarding. (GOF)
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Being something of a cheapskate and not being very technologically minded I would like to know if the following is feasible.

I now have several DCC chipped locos that have yet to be sound equipped. Cost is a factor here so in the short term I was looking for an alternative. I have a number of sound units sourced from various analogue locos which are 'going spare'. I realise they will only have limited capability but on a 'better than nothing' basis could I fit them in DCC locos if they are connected to the DC supply which goes to the motor? It would at least (I hope) give the running sounds associated with the original installation.

Explanatory diagram below.
dc and dcc.png
 
Simple answer, Mike.... Yes.

Though some of the sound unit may not like the PWM motor output of the decoder..

Very easy to test on the bench though. :):nod:


If you have any of the more sophisticated cards (MLS for example), these have power AND motor connections, so you can have 'standing sounds' with these..
There is also the possibility, in the cards have some-sort of 'trigger' to use function outputs from the decoder to trigger sounds. :nerd:
 
Exactly what what was said, although with the isolators and/or bridge, you still get pulses. You have to smooth them with some filtering circuitry.

If the board has separate power and "speed" inputs, this is pretty simple.

If not, then you have to have a higher amperage filter.

Again, some sound units are unaffected by PWM, ask the manufacturer first, or someone with specific experience with exactly that sound unit and pwm.

Greg
 
As I mentioned back in the 2016 thread, Aristocraft produced a PWM(PWC) to Linear converter (57090) for use with the DC track or battery Soundtrack Sierra sound cards.
This board had the basic circuitry components not only to just convert PWC(PWM) to linear but it also had one other function......

The converter enabled the automatic 'chuff' or 'notch' sensing in the Sierra circuitry to see the amount of 'linear' DC being used by the motor, and approximate the correct chuff/notch sound pattern depending on speed.
But also the converter supplied power for the card itself and for charging the small 'back-up' battery (which kicked in when the controlled track voltage dipped below about 7 to 8 volts and allowed 'standing' sounds to work until the Sierra sound board's power-saving setting acted to shut it off).
If there is an external chuff trigger in use on track powered locos, the 'back up' battery enables the chuff sound to carry on over dirty or breaks in the track when power pickup is interrupted so sound is not affected.

If the power for the loco is from battery then the Sierra sound card would need a rectified and regulated voltage supply to its power circuitry connectors.

John has my 57090 board at the moment and the circuit diagrams etc.
He is using his wizardry to investigate producing the simple 3 amp PWC/linear converter (which he has shown above) and also the more complex 'dual' 57090 type which can also supply power to the sound board.
As a bonus the 'plain' 3amp converter should be a quick way of sorting USA Train's locos with lighting circuits that have distinct problems with PWC/PWM voltage (but not for the motor circuit..... those would need the bigger and higher power 10 amp converter to be utilised.

He has also produced a larger size high-power 'plain' PWC(PWM)/linear converter for use with the 'Revolution Super Base Station' track-side power receiver.
 
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3 amps for the entire USAT loco? That might be a bit close in a full load situation. Definitely the stall current is way above that.

I'd probably use a 5 amp unit.

For those people in the USA, G Scale Graphics has them for sale:

PWM to Linear DC Converter

s121332513913518739_p102_i2_w640.jpeg
 
I was referring to using it for the lighting and sound circuits Greg, not the motor circuits. I have also already mentioned this, before, in another thread.
I have been running USAT locos for about 12 years now, and like yourself, have installed sound cards in them, battery power with Revolution kit in a couple of them and also DCC in some of them.
I am only too aware of their stall current and have always advised on having 8 amp stall electronics as the medium solution, 10 amps for security on the bigger locos (althiough I have seen one ailing USAT loco, not mine, stall and easily blow a TE trackside RX's 10 amp fuse.

A 3 amp PWC/linear converter for problematic lighting circuits together with sound card would cover those circuits fine, (unless high draw speaker system playing very loud is used which would pull about 2 amps with some Phoenix cards.... but then again a Phoenix card doesn't mind PWC as long as it is fed with a chuff /notch trigger so would not need to be on the PWC/linear converter circuit).

Anyhow, I have edited my previous post and added that it is for the USAT lighting circuits not the motor ones.
 
The digital sound units I'm familar with operate from either DC/Analog or DCC/Digital inputs, e.g., the LGB 65000 series, Phoenix, and Massoth eMOTION S Decoder. So, you can connect these sound units directly to track power or onto the power decoder if it has pins for a sound decoder.
 
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