# Wiring Sierra Sound on battery power



## alecescolme (Dec 20, 2010)

Hi all, it has been years since I have last posted here. I have had a brief break from the hobby, but am back and busy building again, and working in the garden.

Anyhow, I am wiring up a Shay to run on battery with RCS and Sierra sound. I would like to avoid using a PWM to linear converter, as I plan on using a chuff switch. 

How best to wire it to run directly off the locos battery and have the gel battery redundant?


----------



## Dan Pierce (Jan 2, 2008)

You need the Sierra tech6.pdf file that shows many RC connection diagrams.

http://1stclass.mylargescale.com/stancedarleaf/Aristo REVOLUTION/Tech6.pdf

This is not just the revolution but many RC diagrams of older units.


----------



## Greg Elmassian (Jan 3, 2008)

Dan, what is your opinion about him being able to not use the PWM to linear converter?

Alec, whose RCS do you have, Tony's or Rick's?

Greg


----------



## Michael Glavin (Jan 2, 2009)

I've used the A/C PWM > Linear board together with A/C Revolution and Sierra Sound card without issue. No other components and or circuits were used therein.

Michael


----------



## East Broad Top (Dec 29, 2007)

I've always used an opto-isolator to interface the Sierra with RCS and Revolution boards. Tony Walsham (RCS Australia) used to have them, then Aristo offered one as well. I didn't see Aristo's interface on Crest's web site. The diagrams Dan linked show the wiring diagram of one if you can't find one for sale. 

I've not used the PWM/Linear board, but interesting to see it will work. That does show to be available on Crest's site.

I _think _you can get away without one, but the Sierra will think the loco is always going full speed, so you lose Fireman Fred and other sounds that happen when the loco is at idle. You also can't set the Sierra up for automatic directional whistles or automatic bells. I can't remember if there are other issues, but there's something in the back of my mind that says there might be. I know that if you simply opt not to hook the motor outputs to the Sierra, then it will just shut down after a minute or two because no voltage means "loco stopped, go into shut-down mode until I see motor voltage again."

Later,

K


----------



## Greg Elmassian (Jan 3, 2008)

The speed input cannot be PWM, so there's the 2 ways to get around it. I'd filter the output, since most large scale locos have good slow running characteristics anyways.

Greg


----------



## alecescolme (Dec 20, 2010)

Thanks for the input guys. I will try and build my own interface using the above wiring guide.
Greg, It is one of Tony's old systems.


----------



## TonyWalsham (Jan 2, 2008)

Filtering the output of the 11 pin RCS motor driver IC will cause it to overheat and likely shut down.
There are two solutions to make the Sierra work correctly.
1. Use the Sierra battery and trigger the sounds via relays.
Or:
2. Fit the opto isolator circuit. Unfortunately I no longer make them and am unlikely to ever do so again. You could make them yourself using the circuit devised by Sierra.
Terminals # 2 & # 4 can handle up to 12 volts traction battery input. Any more and the magic smoke will appear. That means a 12 volt regulator.
You could use less voltage but if the Sierra is a diesel sound system, it will not ramp up to notch 8.


----------



## toddalin (Jan 4, 2008)

Or option #3..., 8 diodes and two caps.

Without getting into a schematic.

Put four diodes on the RCS output/motor input, two facing one way and two the other.

Using two 35 volt caps of XYZ mfd, put a capacitor of the appropriate polarity at the end of each pair of diodes so that when the motor sees polarity one way, one cap charges, and when the motor sees polarity the other way, the other cap charges.

Put four diodes after the caps leading to the Sierra "tying" them back together at the sound board input. These would maintain the same orientation as the other four diodes. 

The diodes isolate to motor from the filtering but the caps still filter the voltage going to the sound board while providing the proper directional information. The diodes after the caps keep them from receiving the inverse charge.


----------



## TonyWalsham (Jan 2, 2008)

OK Todd.
I would use Schottky diodes to minimise the voltage drops.


----------



## toddalin (Jan 4, 2008)

Doesn't seem like the voltage drops should be much of an issue.

Doesn't it stand to reason that the capacitors would realize a slightly higher smoothed voltage than the average PWM coming in under the load of the motor?


----------



## TonyWalsham (Jan 2, 2008)

Surely two banks of regular diodes will drop a total of about 3 volts meaning the Sierra will not detect start up until the loco has already started?
Schottkys will drop that to less than 1 volt in total.


----------



## Greg Elmassian (Jan 3, 2008)

Sure makes sense to me, many people have issues with the loco moving before the sound.

Thanks Tony

Greg


----------



## Pete Thornton (Jan 2, 2008)

alecescolme said:


> Thanks for the input guys. I will try and build my own interface using the above wiring guide.
> Greg, It is one of Tony's old systems.


Hey Alec, welcome back to the trains!

My EBT #15 (RYM Mike) has an older RCS Elite from Tony with a Sierra sound system like you are planning. The tech bulletin was very useful. I found a Soundtraxx opto-isolator kit at Star Hobby - as I know you are in the UK I will call Don and ask if they have any left. I think I still have one of the kits, but I'm not going to be in MD until late May so I can't check.

Also take a read of this thread:
http://forums.mylargescale.com/66-o...6-challenge-our-smart-electronics-guys-3.html
Update: I gave Don the info (RC Adapter Kit part number 810111) and he is checking his old stock.


----------



## alecescolme (Dec 20, 2010)

Wow, many thanks for the great ideas guys. 
Todd, your idea sounds quite simple, encorporated with Tony & Greg's ideas.

Pete, thanks for the welcome back and thanks for asking around on my behalf.


----------



## Pete Thornton (Jan 2, 2008)

Alec,
I talked to Don again today, and he says he is still looking through all his boxes and may come up with something ! I'll call him again late week when I get back from Boston- or you could Skype him: +1 410-349-4290.


----------



## alecescolme (Dec 20, 2010)

Many thanks Pete for going to the trouble.


----------



## alecescolme (Dec 20, 2010)

Right an update, I have still been trying to combine the RCS with Sierra without a interface.
I have directly connected the track terminals on the Sierra to the main traction battery. I have then programmed to mechanical chuff. The system seems to work, obviously lost the direction whistles. 

The problem I have is there, when the bell/whistle triggers are wired up, the bell rings when the up/down button is pressed on the tx8 without pressing the shift key? Any ideas?


----------



## TonyWalsham (Jan 2, 2008)

The direction toots will never happen because the system thinks it is continually going full speed in one direction. Also no blow down or automatic dynamo at idle.

If you modify the wiring from the way it is supposed to be, you will possibly get all sorts of weird triggering effects.


----------

