Digital/analogue puzzle

[KeithT]

Earlier today I ran my scratchbuilt Garrett on the NW GScale's new layout.
The layout can run DCC or analogue as needed. The analogue controllers are Gaugemaster.
The Garrett is analogue but I included in the rake a coach fitted with an LGB soundcard. To my surprise on switching on the power the soundcard also fired up at a fairly fast and almost constant rate.
How can that happen?
I have a Sachsen fitted with a Massoth XLS which works on analogue relative to the speed of the loco.

 

[Zerogee]

Could this have anything to do with the Gaugemaster analogue controllers providing PWM output rather than smooth variable DC....?

Jon.

 

[KeithT]

Could this have anything to do with the Gaugemaster analogue controllers providing PWM output rather than smooth variable DC....?

Jon.

Perhaps.
Tomorrow I will try it on analogue on my own layout.

 

[Greg Elmassian]

Yep, they are not "analog" but PWM output. Most people reserve "analog" for real DC.... although that is getting rarer and rarer.


Greg

 

[Zerogee]

Perhaps.
Tomorrow I will try it on analogue on my own layout.

Any update on this problem, Keith? Did it still occur with smooth-DC LGB power?

Jon.

 

[Bram]

In our club some members have experienced difficulties with Gauge master controllers, some to the detriment of the locos, so beware

 

[Tim Brien]

It has long been known that PWM output will fry LGB sound cards.

 

[Greg Elmassian]

Hi Tim!

So, does PWM damage these boards from the pulsing, or the max voltage too high? Usually nothing damaged, just does not work right.

Greg

 

[Tim Brien]

Greg,
many years ago it was common knowledge to not use PWM on LGB sound boards as damage would occur. How it damages the board is unknown to me. I do not recall where the warning came from.

 

[Zerogee]

Greg,
many years ago it was common knowledge to not use PWM on LGB sound boards as damage would occur. How it damages the board is unknown to me. I do not recall where the warning came from.

I also used to believe that PWM could be damaging to DCC decoders, having heard/read it from multiple sources..... I think perhaps it originated with LGB's strict warnings of voided warranty if a loco has been operated on anything other than their own branded smooth-DC power units....?
I now think that it is more likely that it will just confuse the decoder and cause running problems, rather than causing actual permanent damage - but I don't know this for certain, so don't quote me on it....!
Either way, I'd think it's probably something best avoided just in case (and because your loco won't run properly on it anyway).

Jon.

 

[Greg Elmassian]

Yes, I know that there were claims of excessive heating (and demagnetization) of motors, perhaps that spilled over to their decoders.

The motor issues were caused by early PWM that had some really low frequencies, in my opinion.

Nowadays, I cannot find evidence of damage from DCC on a sound or PWM unless the voltage is too high (like 18v bulbs on a 24v DCC system). I do see erratic operation.

Regards, Greg

 

[Hutch]

Earlier today I ran my scratchbuilt Garrett on the NW GScale's new layout.
The layout can run DCC or analogue as needed. The analogue controllers are Gaugemaster.
The Garrett is analogue but I included in the rake a coach fitted with an LGB soundcard. To my surprise on switching on the power the soundcard also fired up at a fairly fast and almost constant rate.
How can that happen?
I have a Sachsen fitted with a Massoth XLS which works on analogue relative to the speed of the loco.

I finally put my analog LGB Sound boxcar on the track and tested it in DCC mode and PWM mode. It comes on at "full speed" when put on the track in DCC mode, or goes to "full speed" when the PWM voltage is at 10% or more "speed" as indicated by the Revolution controller. These are just my unofficial results verified only by a Corgi whose sleep was disturbed.

 

[Greg Elmassian]

What happened is what is expected. The analog sound card sees the full voltage pulses and figures it is going full speed.

Greg