Soundcard To Be Used With Pwm Input

palmerston

palmerston

trains
Country flag
The old analog and newer DCC soundcards/decoders from LGB or Massoth requiere a pure DC input. The pulses from the ESC will disturb the sound.

Anyone know how to solve this? PWM to analog converter readly availble?
 
Seeing as all the soundcard needs a rising voltage to know what to do (but does not care what polarity it is)..

A full wave rectifier, and a small amount of smoothing should sort this. - I assume you will feed the soundcard with power directly from the battery-pack?
 
I suspect these soundcards operate from about 3V - 5V trackpower so powered directly from the battery should work.
 
I run battery power using G Scale Graphics electronics. Oddly, my LGB motorized sound tender and my 2096 Whizzy-cranks sounds are not affected. The LGB simple steam sound card, found in their sound equipped boxcars is. It starts out at full chuff rate and stays there until after the loco has come to a complete stop and the voltage has dropped to zero.
 
Run the LGB old and newer DCC soundcards from LGB/Massoth from the DC battery. Use the Pulse Generator Set part number: 8242030 Manufacturer by Massoth. to Synchronize the locos sound with the wheels rotation.
 
PhilP said:
Seeing as all the soundcard needs a rising voltage to know what to do (but does not care what polarity it is)..

A full wave rectifier, and a small amount of smoothing should sort this. - I assume you will feed the soundcard with power directly from the battery-pack?
Click to expand...
Phil is correct.
It is most important you DO NOT put capacitance across the output of a PWM motor driver. Capacitance will cause them to overheat.
 
Railway42 said:
Run the LGB old and newer DCC soundcards from LGB/Massoth from the DC battery. Use the Pulse Generator Set part number: 8242030 Manufacturer by Massoth. to Synchronize the locos sound with the wheels rotation.
Click to expand...

I once used this on a diesel. It has no effect on the dieselsound despite settings CV values. Massoth sounddecoders use the internal speedsteps for creating the apropiate sounds in case of diesel in dcc mode. Have to ask Massoth if using their sounddecoder in analog mode a pulse generator would be usefull. The RuKB V51/52 diesel has LGB factorysound and a pulsegenerator but current sounddecoders could be different.

Yep, need Dieselsound, no chuffing!
 
Last edited:
Tony Walsham said:
Phil is correct.
It is most important you DO NOT put capacitance across the output of a PWM motor driver. Capacitance will cause them to overheat.
Click to expand...

Hi Tony,
Just to be 100% sure..

Bridge rectifier, and capacitor, is OK. But straight capacitor is NOT?

PhilP.
(But I think I would only put a small amount of smoothing on, just to take the edges off).
 
The old Soundtraxx Sierra boards have to have a linear converter between them and the PWM (PCM) voltage source. The aristocraft 57091 and 57090 linear converters (and the Soundtraxx schematic for building one) are essentially optical isolators to convert the PWM to straight DC.
It should be pretty easy for those with experience of circuitry to knock one of these up...

upload_2016-12-19_20-30-11.png

Converter2.jpg


This is the RCS version

upload_2016-12-19_20-32-29.png
 
Do you have a link to the Soundtraxx schematic? I'm after converting my LGB diesel to RC but want to keep the (integrated) sound which will only work on analogue dc.
 
The RCS SSI-12v5 was designed specifically for the Sierra sound system. The pcb is only to supply a no load linear DC signal for Sierra sound. The pcb cannot carry a load.
The circuit design was supplied by Sierra many years ago. I still have a few left.

The Crest 57091 shown is slightly different to the one I use currently. It is designed to carry a load such as the motor(s) inside a loco. It works well at removing any audible hum/whistle. I use them in the smaller scales to filter the PWM output of my Trackside R/C.
When used with an H0 DCC sound equipped E8 the loco is super smooth with pwm but the sound is not as crisp. With the 57091 fitted in the circuit, the sound works better but the trade off is a noticeable loss of smoothness at low speed.

I know nothing about the top device
 
I am amazed at how this thread suddenly comes to life.
 
Here is the Soundtraxx schematic as requested......

sierra board interface linear converter.jpg
 
You must log in or register to reply here.
Back
Top Bottom