# sierra sound board



## lotsasteam (Jan 3, 2008)

Run into another sierra sound board,calling twice Soundtraxx service department but still no answer! The sierra soundboard i have has a 1/4 inch white sticker on the :1-8 pin side which say's 
: k 504 Is it a steam or diesel module ?


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## toddalin (Jan 4, 2008)

Assuming you have the board in your possession, it only takes a few moments to fire it up and see, and you'll also know if it works. 

Put a variable power supply on pins 7 and 8, and an 8 ohm speaker on pins 9 and 10 and plug in your supercap or 6 volt battery to the green plug and it should fire up when power is applied to pins 7 and 8. If using a supercap, bring the power up to >9 volts and wait a moment (it may "motorboat") for it to charge.

Don't use a 4 ohm speaker, especially if using a supercap! This will exascerbate the motorboating and the board will get warm.

If it is a working diesel and you want to part with it, let me know.

BTW, I think I recall seeing the K504 on the board I sent to you.


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## lotsasteam (Jan 3, 2008)

*sierra*

Your sierra just arrived ,i snapped a pic of both boards,bottom one is from you the top one is tagged K 504
I can not check the board ,if its steam i will hook it up but my revolution will not let me use diesel without the converter board which i don't have!
Would be nice to id the K 504

Manfred


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## toddalin (Jan 4, 2008)

lotsasteam said:


> Your sierra just arrived ,i snapped a pic of both boards,bottom one is from you the top one is tagged K 504
> I can not check the board ,if its steam i will hook it up but my revolution will not let me use diesel without the converter board which i don't have!
> Would be nice to id the K 504
> 
> Manfred



Do you have a 12 volt battery/pack lying around? You can use that as the power source (pins 7 & 8) and you'll have your answer.


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## East Broad Top (Dec 29, 2007)

Here's a link to a circuit diagram for an opto-isolator circuit that you can use to go between the Revolution and Sierra. 

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

In a recent thread here, someone mentioned you can use the Aristo PWC/Linear converter board instead of an opto-isolator. 

Later,

K


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## lotsasteam (Jan 3, 2008)

Todd,its another diesel,wanna swap for another steamsound? Manfred


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## toddalin (Jan 4, 2008)

My three steamer cards (C-16 in a C-16, Mogul in a C-16 and Shay in a Shay) are all in use. But I would be happy to purchase it from you or make a trade for something else.

I have a single LGB 2065 diesel or ... I would trade. Sorry, no steamers (just traded a Hartland steamer for a covered bridge).


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## Jerry McColgan (Feb 8, 2008)

East Broad Top said:


> Here's a link to a circuit diagram for an opto-isolator circuit that you can use to go between the Revolution and Sierra.
> 
> http://1stclass.mylargescale.com/stancedarleaf/Aristo REVOLUTION/Tech6.pdf
> 
> ...


The Sierra units worked great. Eventually they ran out and sold just the circuit board but now of course Radio Shack is leaving the scene. 

The Aristo CRE-57091 Base Station PWC to Linear unit was intended to remove PWC and provide pure DC for folks like me who had some equipment that did not like PWC. I bought some but have not used any of them yet. I think Aristo ran out of inventory quickly and only had a single shipment so they are probably hard to find (just guessing).

Dave has an excellent write up on them.

http://www.trainelectronics.com/ART5700TrainEngineerRevolution/PWC--Linear_CRE57091/

The difference is that Sierra units were needed for the individual Sierra Sound Systems while the Aristo unit filters the entire output of an Aristo Base Station.

Both units sold for about the same price which is amazing. The Aristo unit is a LOT larger which is understandable since it is intended for the power of a Base Station rather than for an individual sound board.

Jerry


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## beavercreek (Dec 12, 2008)

Aristo also did a smaller linear converter 57090 which was specifically made for using boards like the Soundtraxx Sierra with the Revolution.
I have been trying to track down some of these but they have long gone. 
The only source, now, would probably be folk who are either upgrading the Soundtrax soundboard to a Phoenix one (which does not need the conveerter) or who might be getting into DCC with DCC sound decoders.

I live in hope!


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## toddalin (Jan 4, 2008)

Or...,

You use a pair of caps and some diodes to create a filter to smooth the PWM for the Sierra. I believe that I had described the circuit in another thread and you should be able to search for it.

I don't know that anyone has done it, but see no reason why it shouldn't work.


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## Greg Elmassian (Jan 3, 2008)

might be easier with a couple of coils also Todd


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## TonyWalsham (Jan 2, 2008)

.......and make sure the capacitance is behind a diode bridge otherwise the caps across the PWM output may cause the ESC to overheat.


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## toddalin (Jan 4, 2008)

Greg Elmassian said:


> might be easier with a couple of coils also Todd


Where/how would you put the coils?


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## Greg Elmassian (Jan 3, 2008)

Make a "normal" filter for smoothing the pulses.

Are you familiar with the terminology like a "single pole filter" or a "3 pole filter"? 

If so, then normally you use a 2 pole filter in this case.

Look at the unit Aristo sold, and the one Tony sells.

Greg


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## toddalin (Jan 4, 2008)

Greg Elmassian said:


> Make a "normal" filter for smoothing the pulses.
> 
> Are you familiar with the terminology like a "single pole filter" or a "3 pole filter"?
> 
> ...



No, no, no. You're not doing this for me! 

Describe the circuit in detail, including component values, so that the OP can build it for his use in this particular case.


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## TonyWalsham (Jan 2, 2008)

Thanks for the plug Greg, but I have never made a pwm filter pcb like AristoCraft did.
I did make an opto-coupler # SSI-12v5 interface so that a Sierra Soundtraxx could follow pwm voltage. They are no longer available.


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## toddalin (Jan 4, 2008)

Greg Elmassian said:


> might be easier with a couple of coils also Todd


Come on Greg, show us how to do it easier using a couple coils.

If your method is cheap and easy, with readily available parts, I may add it to my Sierra boards so I can run my trains using the PWM mode, rather than linear mode, on my Train Engineers.

We are all ears/eyes.


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## Greg Elmassian (Jan 3, 2008)

Sorry Tony, I thought you offered a high current filter at one time.

I'd use the one that Aristo made as a model:










http://www.trainelectronics.com/ART5700TrainEngineerRevolution/PWC--Linear_CRE57091/

Todd, I would say "oh no you are not going to do this to me" .... Whenever you are challenged, it seems to degenerate into proving I am wrong, you are right, rather than the quest of knowledge or the best answer.

This stuff is not new, and no matter what I tell you, you don't believe me, so I'm sure you have friends much smarter than me, ask them about filter design.


Greg


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## toddalin (Jan 4, 2008)

Greg Elmassian said:


> Sorry Tony, I thought you offered a high current filter at one time.
> 
> I'd use the one that Aristo made as a model:
> 
> ...



I'm not doing anything to you.

_You presented the challenge that it could be done easier using coils_ and I want to see it, that's all. You can't expect to "coat tail" on my posts saying that something can be done easier than I've already suggested, then not support it. You should know that by now.

I don't see how this is easier/cheaper than some 1 amp diodes and the two caps I suggested, that they used anyway. Your suggestion was that somehow these caps, that I suggested, could be replaced with coils, and that's not happening here. If anything, this supports my method.

And what is the value and source of the coil they did use? Remember we are talking super easy/cheap/do it yourself.

Also, I note that board shows + and - output and you should know that's not going to cut it when the sound needs to start with three toots so it _appears_ that it won't even do the job at hand! 

It looks to me like they could possibly do the bi-directional by adding the diodes to the circuit.

BTW, I'm not the one being challenged..., you are. And to quote yourself "Whenever you are challenged, it seems to degenerate into proving I am wrong, you are right, rather than the quest of knowledge or the best answer."

Thank you Captain Dunsel.


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## Greg Elmassian (Jan 3, 2008)

No sale Todd, you need to try a new game, or better bait.


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## Dan Pierce (Jan 2, 2008)

I would like to see the bottom of the 57091 board (to see the etches (read wiring) as I suspect the caps were reversed in polarity in the one I saw.


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## Greg Elmassian (Jan 3, 2008)

Dan, if you followed that link, Dave, as usual, has documented everything very well.

I'll post the bottom here:









If you work the circuit out, you see the 2 electrolytics are connect in series to make a NPO capacitor.

Todd, this is a basic "one pole" filter, and the basic sense of this design is that the capacitor helps remove "ripple" but as Dave says, the "heavy lifting" of converting the pulses to more constant DC is done by the inductor, which can handle the current. When you start making high current filters, getting components that can take 5 amps or so adds design limitations.

This is really basic filter design, which is fine, simple and effective. (Notice the mica capacitor and the resistor, to shunt the very high frequency components, normally called a bypass cap).

Greg


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## Greg Elmassian (Jan 3, 2008)

I just saw that I did not answer Todd's question.

While the single pole filter (with the RF bypass) appears effective in this case, if it was me converting PWM to DC, I would add a second pole/section.

In this case, you would just use 2 boards in series, which would make a 2 pole filter, and indeed use the "couple of coils" as I described.

If you want to build one of these yourself, ask Mr. Bodnar to measure the inductance of the coil and then you could order one from DigiKey or Mouser.

Alternatively, buy one, send it to me and I'll measure it (and return it) for you.

How's that for a nice offer after your (retracted) comments?

Greg


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## toddalin (Jan 4, 2008)

Greg Elmassian said:


> I just saw that I did not answer Todd's question.
> 
> While the single pole filter (with the RF bypass) appears effective in this case, if it was me converting PWM to DC, I would add a second pole/section.
> 
> ...













If the "OUTPUT" is simply + and - as indicated on the board, regardless of the input, I still don't see how this is going to give the reverse current to the Sierra for three toots, so it would at least appear that it still doesn't accomplish the task at hand.

Are you saying that the markings on the board are to be ignored or are incorrect?

And I still don't see how this is easier (especially if they are made of unobtanium), and contend that the caps are still necessary and this could not be done just using coils as you indicated when you jumped on my post.

Oh, and did you forget? This can't work in the case of the Sierra Board because according to Tony (and even yourself in the other thread), ".......and make sure the capacitance is behind a diode bridge otherwise the caps across the PWM output may cause the ESC to overheat." That piece would appear to place the cap across the motor in this instance.

BTW, in reference to the circuit, the small cap, choke, and resistor form a simple LCR, 2nd order, low pass filter to filter the high frequency component and hash. The work of smoothing the pulses is handled by the big caps. And, this is not a case of a "bypass capacitor" where a small value cap is "piggybacked" on a larger cap to help add "edge" such as in a speaker crossover network, such as those I built for my big JBLs, or an amplifier's power supply. 

I'll leave it at that.


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## Greg Elmassian (Jan 3, 2008)

This is what caused me to respond... the previous posts are about the Aristo converters... I responded with the Aristo converter information.




toddalin said:


> Or...,
> 
> You use a pair of caps and some diodes to create a filter to smooth the PWM for the Sierra. I believe that I had described the circuit in another thread and you should be able to search for it.
> 
> I don't know that anyone has done it, but see no reason why it shouldn't work.


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## Greg Elmassian (Jan 3, 2008)

Todd, you have the distinction of being the only person I have ever put on an ignore list.

That means I will never see one of your posts again. Period.

No matter what you post I won't see it.

You may have to pick someone else to harass, sorry.

Greg


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## toddalin (Jan 4, 2008)

Thank you Greg.


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## East Broad Top (Dec 29, 2007)

I'm glad to see you two sorted things out for yourselves without needing the mods to get involved. 

Anyway, in response to Todd's question about the polarity markings on the Aristo board, they're irrelevant. I haven't a clue why they're there. The output polarity changes with the input polarity. Again, I've only heard anecdotally that this board works as a go-between with the Sierra, but according to *Crest's web site*, they are still available.

Later,

K


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## Dan Pierce (Jan 2, 2008)

When I look at the 2 capacitors back to back without diode protection, I would venture to guess that each has half the voltage thus making one have polarity reversed.
I would have placed a diode across each to limit the reverse polarity to less than a volt unless Aristo found capacitors with a diode built in.


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## Greg Elmassian (Jan 3, 2008)

Please read this about using 2 polarized caps back to back to make a non polarized capacitor, pretty common practice, saves money over a "real" NPO cap.

http://electronics.stackexchange.co...tic-capacitor-out-of-two-regular-electrolytic

There is an explanation about how the reverse bias is handled.

Greg


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## Dan Pierce (Jan 2, 2008)

Thanks Greg, great info.


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## Greg Elmassian (Jan 3, 2008)

It's not something you would normally do commercially in top end equipment, but for our use, it's an inexpensive solution that works well enough. I have not had any reports of exploding caps yet.

It's interesting that they also added the high frequency bypass cap, since the PWM rate is so low, you would not think there would be a lot of HF noise, but, again, it's cheap enough to include. Notice that the resistor is there to limit the current through that cap, a nice touch. I don't have one of these units myself, so I don't know the component values, but maybe someone does and then we can put the circuit up somewhere for others to use.

Regards, Greg


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## toddalin (Jan 4, 2008)

Calculator for LCR low pass filters.

http://sim.okawa-denshi.jp/en/RLClowkeisan.htm


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## East Broad Top (Dec 29, 2007)

(Reference to deleted posts) Gentlemen, I complimented you earlier on coming to the conclusion on your own that it's sometimes better simply to ignore someone with whom you have a disagreement on the forums. To that end, it is unnecessary to remind the other individual that you are ignoring them whenever they post. 

Later,

K


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## Greg Elmassian (Jan 3, 2008)

Yep, I agree, except I felt after that many harassing posts and inaction by moderators and the appearance of posts from Todd immediately afterwards (twice), I needed to confirm I really was not reading them or seeing them.

This has been going on for a long time, so I think you OWE me the courtesy of one single comment. I stated that I would only post it once... perhaps you did not see that?

This all assumes you were pointing at me Kevin. If not, please delete this post. In fact, why not delete yours and mine, since BOTH are unnecessary, you already commented earlier too!

Greg


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## East Broad Top (Dec 29, 2007)

Greg, I was calling out _both _of you, as both of you posted comments after you said you were done commenting. This schoolyard bickering has no place on the forums. 

Later,

K


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## Greg Elmassian (Jan 3, 2008)

Kevin, I did not say I was not going to comment... here's my post quoted below in simple English.

I said I was putting him on my ignore.

Then he posted right afterwards.

Knowing the situation, I reinforced that the "ignore" was indeed working, and I was not seeing his posts.

This is not bickering, he has harassed me and made many personal comments and the moderators have not risen to the occasion, the evidence is on this forum, he is the instigator. I try to ignore it but it continued unabated. Sophisticated baiting and name calling. 

So, your comment could have never been made, although I have no idea what Todd is posting, but keep it to yourself please or to Todd, I do not deserve this at all, the moderators failing to stop people making personal comments has clearly (and historically) emboldened people to continue to do so, and clearly in this case I had to seek protection elsewhere than moderation.

Greg



Greg Elmassian said:


> Todd, you have the distinction of being the only person I have ever put on an ignore list.
> 
> That means I will never see one of your posts again. Period.
> 
> ...


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## East Broad Top (Dec 29, 2007)

Greg, Todd's post had _nothing to do _with anything you posted. No, you wouldn't have known that since you're ignoring his posts, but _because _you can't see what he's posting, you can't just assume he's saying something about _you_. He wasn't. You felt the need to "remind" him you were ignoring his posts even though you didn't even know what he was posting, and he felt the need to respond in kind. Both posts were over the line, so they were removed.

Your concerns about your treatment on these forums have been noted by the moderators. 

*Further discussion on anything other than filter boards for interfacing between various control systems and Sierra sound boards will get this topic locked.*

End of story.

K


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## Greg Elmassian (Jan 3, 2008)

Great, back to trains!

I also understand that there was a "smaller" board from Aristo, that did not handle as much current, but could be used for the "speed feed" to a sound card.

I don't have a picture of it. It would be interesting to see it's circuitry.

Also, if anyone does have the board and wishes to sell it to me, I'll pull it apart and measure the inductor, so interested people can duplicate the circuit.

update: the smaller board is a cre57090, 









looking for a bigger picture and specs.

Update 2: the 57091 board is listed as in stock and $18 at crest-electronics.com .... buy them now!

Regards, Greg


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## East Broad Top (Dec 29, 2007)

Greg, go back to my first post (post #5) and the link to the Soundtraxx technical bulletin. Go to page 2 of that document and look at the top diagram. In looking at my Aristo 57090 board, it appears to be that circuit. All of the components are there and in tracing the circuit, the wiring appears to be identical. Aristo labels the components differently (C1 is C3, etc) but that appears to be the only difference. 

It's a fairly simple optoisolator circuit with a variable voltage regulator circuit setting the voltage that feeds the Sierra board's power input, and also providing +v for the two optoisolators which take in the voltage going to the motor and translate that into whatever it is the Sierra needs for that input. 

Later,

K


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## Greg Elmassian (Jan 3, 2008)

It would make sense that the 57090 is the same circuit, since it is no longer produced by anyone else.

Right now, I think the 57091 is available, and I believe the discussion turned that way because of the simplicity of the circuit and the nice large components that people find easier to work with.

All of that said, the 57090 / soundtraxx circuit would be, in my mind, the more elegant solution although that regulator needs a heat sink on it.

Greg


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## TonyWalsham (Jan 2, 2008)

.............and before anyone asks I am not planning on making my SSI-12v5 again.
They were based on the Sierra design and worked well. However, they were definitely not an In Line Filter for PWM output ESC's.


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## Greg Elmassian (Jan 3, 2008)

Right these two distinctly different designs can be used with the Sierra to accomplish the same end result, albeit in completely different ways.

Greg


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## TonyWalsham (Jan 2, 2008)

Not completely correct Greg. At least not with battery powered R/C.
The PWM filter can only be used to power the Sierra if the Sierra is powered by its own battery.
If you use the loco traction batteries to power the Sierra there will still be a sneak path back to ground such that the Sierra thinks it is seeing full speed and reacts accordingly.


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## Greg Elmassian (Jan 3, 2008)

We're talking revolution and sierra here, as I understand.

The diagram kevin linked to on the first page has a bunch of setups, Soundtraxx technical bulletin #6m, but that is for the optoisolator setup

So, if we are talking the "filter", what you are saying if you power the Sierra from the battery through the filter, there is still a problem, right?

Am I mistaken if the sierra is powered from the filter only, then you don't have a sneak path? Or is the issue if you do this, then the sound dies when stopped?

Maybe that is the issue.

I'm listening Tony.

Regards, Greg


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## TonyWalsham (Jan 2, 2008)

I can't comment about the Revolution but I can tell you about the H Bridge motor driver I use. On the LMD18200T both output legs are always full traction battery voltage. It works by taking one leg to ground depending on what direction is selected.
If the Sierra is connected to the traction batteries and then powered by the ESC motor driver output, the Sierra will always have an internal sneak path back to ground and will think it is seeing full voltage from the ESC even though the system has no voltage going to the motors.
If the Revolution H Bridge drive works the same way, it will do the same thing. The only difference is what sort of resistors have to be added to the circuit. See Kevin's circuit.


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