Converting Accucraft K-27 to battery r/c

[Rhinochugger]

- not sure how I would incorporate a DPDT CO switch here, if even possible ....

Mmm, the jury's still out on the necessity for a 'centre off' - many of the pre-wired options don't come with that, and only a couple of my battery powered locos are wired that way.

Fine if you have the space, but IMHO not a fundamental necessity, the main reason being that absolute switch off is not a requirement, particularly with intelligent chargers - so without a CO switch, it's simply either / or

Might be different if you were to leave your loco out in all weathers - but we don't

 

[beavercreek]

Max,
I think you may have problems with the existing Sierra Sound card??

Don't think it will like a PWM motor voltage from the Cobra..

You are spot on Phil.
Aristocraft used to make a PWC(PWM) converter (ART 57090) for use between PWM devices like Revolution RX (and coincidentally DCC decoders) and the Sierra sound cards, but obviously they are not around and Revolution Electronics do not make one suitable anymore ......SO......
I supplied my last real converter Aristocraft jobby to John S on this hallowed forum and he has built some others for me.

He has already built replacement Accucraft voltage regulator lighting boards for Max so perhaps.............

Aristocraft 57090 PWM to linear converter with the 'copy' that John S built

 

[Deleted member 4232]

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[maxi-model]

Hello John, nice to see you here Seems I may need your assistance again.

First off Fosworks were informed when I placed my order by phone that I had a Sierra Soundtraxx card fitted - no mention was made by them of any problems with the use of the Cobra esc in conjunction with this sound card and their website does not mention the dreaded (oft mentioned here) PWM by name with this esc, just the term "high frequency" which I guess is code for PWM. I got the impression then they were not familiar with either my loco or its sound card and even tried to sell me a My Loco Sound card without any real reason. I will agree the combo I have may not come up that often this side of the pond. They seem to have been mostly oriented to G1 in the past.

Next the Cobra you are looking at has not been wired as per my instructions. As I understand it the 2 centre terminals shown, both marked MOT are the voltage output from the esc. I asked, due to my loco's size and installation requirements, for 2 pairs of 6" long red/black wires to be placed there - that didn't happen, I got the std pair of blue/yellow stub wires and a pair red/black with a JCT-BEC connectors (I can do slice and splice ). I assume the 2 outer terminals, marked +ve/-ve are the main battery input to the esc. For some reason these terminals have had 2 pairs of red/black wires soldered in, one pair long, one pair with a female JCT-BEC connector that is I assume to go with the switch/charger wiring loom and thence to the battery pack. Note - the supplied manual for the Cobra does not actually show how these terminals are marked on the card or even the correct positions, something Fosworks say they need to update

My plan was to take one pair of wires from the esc's voltage (MOT) outputs and take them direct to the terminal board in the loco to provide power to the motors and via the voltage controller to the head and classification lights. The other pair of output wires from the esc (MOT) I planned to wire in as per the Sierra's schematic - i.e. one wire to the left pick up position on the power switch installed (which then passes trough to the Sierra card's terminal 8, top right looking at the schematic) the other to terminal 7(usually right pickup) below it. The rear voltage controlled, tender mounted light would be connected to terminals 8&7 too. Essentially it would be parallel wired to get the same voltage output as being fed to the motor and via the other(smoke box mounted) voltage controller to the front lights.

My Sierra card has its own 6v lead acid battery power source installed, it will only use the varying voltage inputs from the esc/loco battery pack to trigger predetermined sound sequences. I do not believe it uses the loco battery to "trickle charge" its own independent 6v battery supply. I need to have a root around the tender just to check how it is wired in up in there at present.

I will be giving Fosworks a call on Thursday. Are we saying using the Cobra is doable with a linear converter of should I ditch it and seek an alternative? And if so what ? Thanks to all for your valuable inputs so far . Max

 

[Rhinochugger]

MMmm, I think the Cobra is one of the few (possibly two) ESCs capable of taking more than 12 volts - I believe it's the ex-Peter Spoerer offering (which is a fine ESC).

I think there is a Viper that is beefy enough to go over 12v but I'm not sure if it's railway orientated with cruise control

 

[Deleted member 4232]

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[Tony Walsham]

Sierra will work just fine with a pwm output ESC as long as that is the only connection between it and the ESC.
You will not be able to use an electronic R/C trigger to trigger the sound functions. What you could use to trigger the sounds, is an R/C trigger that controls isolating relay contacts.

It is possible to do away with the Sierra battery and use the traction battery pack as long as the ESC pwm output is isolated from the Sierra by the use of an opto isolator arrangement.

 

[Rhinochugger]

Do agree with you, Fosworks really do need to up their game with respect to documentation and be much more specific with their designations for inputs and outputs.

If the the following pictures match your existing setup, some alternatives on how it might all go together.

May be worth forwarding them to Fosworks to confirm the thinking.

View attachment 245262

View attachment 245263

View attachment 245264

I'm pretty sure that Fosworks are also going with the Peter Spoerer thinking, and this was that by using the JS plugs in a 'plug and play' scenario, by keeping the male / female connectors in the right place, the gear could be assembled without the possibility of doing it wrong, thus avoiding the need for technical instructions.

That's possibly OK, but then if you depart from the prescribed set up in any way, shape or form .............................. a little guidance would be nice

I came unstuck with a second hand Spoerer ESC that had the JS terminals removed, but the leads were labelled ................ until the labels came off. I actually mis-wired it, and it survived

 

[PhilP]

Cobra:
Blue and yellow are motor wires, traction AND sense for sound card.
Red and black are battery-in.
The 3-wire 'servo-style connector is control from the Omni, and BEC power to the Omni.

 

[beavercreek]

The steam sound sierra board is happy with PWC as long as the chuff rate is mechanically triggered.

If the soundboard is set to 'auto' trigger and supplied with track PWC (PWM) or ESC PWM or DCC PWM then it will sound at the maximum chuff rate (or notch rate for dismals).
Of course a battery powered ESC's controlled PWM might be fine BUT it may confuse the Sierra board's settings and give some less than acceptable results.

The problems arise with track DC PWC, or DCC decoder output, because the nature of PWC (PWM) is to have a quick 'oscillation' between maximum track voltage (eg 19v and the actual setting on the controller).
Motors do not see this 'oscillation' so just function as normal, tungsten lights do see it and glow at their maximum brightness (which gets over them being dim when stationary or at low speed).
The Sierra board's auto chuff/notch trigger also sees this 'oscillation' and that is why it registers the top speed setting.

The Aristocraft converter 57090 (and John S' version) will give a non PWM output and allow the Sierra board to see the controlled speed setting for the auto chuff and not be 'confused'.

 

[maxi-model]

John S, yes my Sierra's manual is the same as you have put up.

Tony - So you are saying the Cobra esc with the Sierra card will be ok so long as I retain the card's existing 6v power source and the only thing that the Cobra is used for is to provide a voltage input to trigger those sounds that are triggered by voltage input variations alone ? The chuff is triggered by a reed switch and magnets on one of the tender wheels, not by voltage input. I can always keep the two sounds I want to activate independently, the bell and grade crossing whistle, as they are using the existing reed switches mounted under one of the tender's trucks. R/C is a "would be nice for those.

Looking inside the tender it seems terminal 8 on the board is "gounded" on the tender's chassis on one of the speaker's mounting screws, rather than going direct to the power switch as shown in the schematic. I have not been able to chase a wire attached to another mounting screw on the speaker, apart from it's path to the tender mounted voltage regulator. I assume this all eventually leads to the power switch shown on the schematic.

I am coming to the conclusion, regrettably, that despite this installation's apparent initial simplicity, it would probably be more advisable to go to a specialist to have the installation done professionally, I have someone in mind. Looking at sorting out some of the wiring work in the tender I really don't feel that encouraged.

I still don't rule it out doing it myself though, it's just a matter of confidence. But...........

Edit - Mike I just have seen your post and now I'm totally confused



Just a little picture of the terminal block I keep refering to, Greg. There is just a simple 2 pin connector between the loco and tender, at the end of those red and black leads you see disappearing at the bottom of the picture.The drawbar is isolated from the loco chassis, I have removed it and its mounting plate. Looking at the the posts on the block the 2 innermost appear to have the heavier motor leads attached and the 2 outermost the wires that match the thickness of those the from the smokebox mounted voltage regulator board (which is isolated from the loco's chassis). The 4 posts are electrically connected as pairs, 2 on the left together, 2 on the right likewise. I cannot see any obvious means of transferring current from wheels for distribution to the motor, unlike the tender where there are "wipers" fitted to one side brushing those tender wheels. Hope that is all clear.

 

[beavercreek]

Sorry if I have stirred up confusion Max
I was sort of replying to a couple of other posts in the thread.

The Soundtraxx sierra board really needs DC (straight track or battery power) BUT it will put up with PWC as long as things like the chuff rate are actually triggered mechanically.
If you look under your tender you will see some small magnets on one of the wheels and a sensor glued to the bogie frame. That is the sensor trigger that tells the Sierra Board how fast the loco is travelling and how many chuffs to sound.
If you turn the sound on and then push the tender on its own and, as long as the big back-up 6V battery is charged, it will chuff as the magnets trigger the sensor.

This 'mechanical chuff system' will work with PWC (PWM) as the Sierra board is not having to sense the voltage to make the chuff speed.

The only problem comes with the sounds that are put on auto mode on the Sierra board (grade horn blasts etc... see the instruction manual) which are not mechanically triggered by magnets in the track etc. PWC can sometimes confuse the Sierra board and make these auto-generated sounds go off all over the place.

HOW IT IS IN YOUR TENDER AT THE MOMENT:
A double cable links between the loco and tender
In your tender is the wiring that:
A) picks up from one side of the bogie axles and goes to the terminal block in the tender then single (of two) cable out to the loco..... also from the tender terminal block, one cable goes to the regulator (like the one in the smokebox) and then to rear light
B) takes the single feed back from the loco to the tender terminal block and goes through to the voltage regulator (like the one in the smokebox) and then one cable from regulator to the light to the rear light
C) the power feeds for the Soundtraxx sound card which will use both of the feeds above. (one goes to terminal 8 on the board and one goes to the on/off power switch under the water filler cover). There is also the Sierra back-up battery specific cabling.
D) The wheel magnet chuff trigger feeds to the Sierra board (terminal 11 &12 in the diagram)

The wiring diagram below is how the basic DC track power set up and how it is in your tender at the moment.
The left and right rail pickup feeds (A and B above) not only power the board and feed the voltage for the 'auto' chuff gauging system (you are not on auto chuff as you have a magnet trigger) but it also charges the back-up battery.

You will not need the separate back-up battery as you will be using a big power battery and this can do both jobs.

Do not get rid of the mechanical magnet chuff triggering it is practically bang on for 4 chuffs per revolution and not only does it work with PWC, it is always more accurate than using the auto-chuff system.


To get rid of any PWM problems you will be using one of John S' converters.
When you change over to the RC setup you will be using terminal 8 & 7 to connect from the PWM converter.
The other end of the PWM converter will connect to the loco feeds from the RC ESC (also called the motor feeds)

Here is a diagram for John S as it shows what is needed for a converter for a battery powered PWM ESC ....

Although you will not need a backup battery, the Sierra board does need to see about 6 to 8 volts at its back-up battery connector...that is why you need the 8v output shown in the diagram below.... the copy of the Aristocraft, converter that John S will create, supplies this Motor output and the 8v for the back-up battery connector





If you are having any problems or need a hand in the installation bring her over and we can set it up over here. It would be good to see her again!!

 

[Rhinochugger]

 

[maxi-model]

Sorry if I have stirred up confusion Max
I was sort of replying to a couple of other posts in the thread.

The Soundtraxx sierra board really needs DC (straight track or battery power) BUT it will put up with PWC as long as things like the chuff rate are actually triggered mechanically.
If you look under your tender you will see some small magnets on one of the wheels and a sensor glued to the bogie frame. That is the sensor trigger that tells the Sierra Board how fast the loco is travelling and how many chuffs to sound.
If you turn the sound on and then push the tender on its own and, as long as the big back-up 6V battery is charged, it will chuff as the magnets trigger the sensor.

This 'mechanical chuff system' will work with PWC (PWM) as the Sierra board is not having to sense the voltage to make the chuff speed.

The only problem comes with the sounds that are put on auto mode on the Sierra board (grade horn blasts etc... see the instruction manual) which are not mechanically triggered by magnets in the track etc. PWC can sometimes confuse the Sierra board and make these auto-generated sounds go off all over the place.

HOW IT IS IN YOUR TENDER AT THE MOMENT:
A double cable links between the loco and tender
In your tender is the wiring that:
A) picks up from one side of the bogie axles and goes to the terminal block in the tender then single (of two) cable out to the loco..... also from the tender terminal block, one cable goes to the regulator (like the one in the smokebox) and then to rear light
B) takes the single feed back from the loco to the tender terminal block and goes through to the voltage regulator (like the one in the smokebox) and then one cable from regulator to the light to the rear light
C) the power feeds for the Soundtraxx sound card which will use both of the feeds above. (one goes to terminal 8 on the board and one goes to the on/off power switch under the water filler cover). There is also the Sierra back-up battery specific cabling.
D) The wheel magnet chuff trigger feeds to the Sierra board (terminal 11 &12 in the diagram)

The wiring diagram below is how the basic DC track power set up and how it is in your tender at the moment.
The left and right rail pickup feeds (A and B above) not only power the board and feed the voltage for the 'auto' chuff gauging system (you are not on auto chuff as you have a magnet trigger) but it also charges the back-up battery.

You will not need the separate back-up battery as you will be using a big power battery and this can do both jobs.

Do not get rid of the mechanical magnet chuff triggering it is practically bang on for 4 chuffs per revolution and not only does it work with PWC, it is always more accurate than using the auto-chuff system.

View attachment 245273
To get rid of any PWM problems you will be using one of John S' converters.
When you change over to the RC setup you will be using terminal 8 & 7 to connect from the PWM converter.
The other end of the PWM converter will connect to the loco feeds from the RC ESC (also called the motor feeds)

Here is a diagram for John S as it shows what is needed for a converter for a battery powered PWM ESC ....

Although you will not need a backup battery, the Sierra board does need to see about 6 to 8 volts at its back-up battery connector...that is why you need the 8v output shown in the diagram below.... the copy of the Aristocraft, converter that John S will create, supplies this Motor output and the 8v for the back-up battery connector

View attachment 245275



If you are having any problems or need a hand in the installation bring her over and we can set it up over here. It would be good to see her again!!

Thanks Mike, I think I can pretty much understand all you are saying in this post. Essentially what you have written is that provided I have one of John's little gizmos, that is interposed betwixt pwc emitting Cobra esc and Sierra Soundtraxx card, then all will be hunky dory and things will function much as before but with those programmed sounds requiring a voltage inputs supplied from the r/c esc/18v battery source rather than the track. And there might even be the added bonus of being able to ditch the Sierra's 6v lead acid battery and rely alone on the loco's 18v pack for all power requirements. Have I comprehended this correctly ? Max

 

[beavercreek]

Thanks Mike, I think I can pretty much understand all you are saying in this post. Essentially what you are written is that provided I have one of John's little gizmos, that is interposed betwixt pwc emitting Cobra esc and Sierra Soundtraxx card, then all will be hunky dory and things will function much as before but with those programmed sounds requiring a voltage inputs supplied from the esc/board battery source rather than the track. And there might even be the added bonus of being able to ditch the Sierra's 6v lead acid battery and rely alone on the loco's 18v pack for all power requirements. Have I comprehended this correctly ? Max

I think you are there Max.
As long as the Sierra board has the converted 'motor' feed to terminals 8&7 and the 8V feed to the back-up battery terminal (although you will not need a back-up) as this is what will prevent the board doing its 'popping' noise response to voltage lower than around 5.5V.... you will be fine.

 

[Deleted member 4232]

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[maxi-model]

Just the RC switch to sort out then?

View attachment 245279

Is that what I think it is ? Nice With regards to the r/c switch - The Omni 2 T/X has 3 buttons that can be used to send a signal to the Rx2. Each button can be for either momentary or latching operation instructions to the Rx2 receiver. Fosworks list a 3 way connector that links from the Rx2 to a sound card but there is no picture or description of this items operation or if it would even be suitable in this application. Their regular 2 way switcher (that I have used previously with a Spektrum R/X, Mac 5 speed controller and My Loco Sound card) does not work with the Rx2. I already have 2 sounds on the Sierra, bell and whistle @terminals 13 & 14 respectively, wired to 2 reed switches mounted under one of the tender trucks and activated by track magnets. Allowing these to be activated from the Omni2 T/X is a "would be nice" but not essential. Max

 

[beavercreek]

As the reed switches are connected directly to the sierra board (like the chuff reed switch trigger) and they are triggered by track magnets, they will work totally independently of the Fosworks ESC etc.
It is only if you want the bell and whistle to be operated, not by track magnets, but by the remote, that you will need to do some wiring from the ESC to the Sierra board trigger terminals

 

[Tony Walsham]

If you want the Sierra sounds to be triggered by remote use a relay output R/C switch, rather than a solid state R/C switch, on any spare channel.
The relays isolate the Sierra from the ESC circuit.
MRW dual relay switch

 

[dunnyrail]

Mmm, the jury's still out on the necessity for a 'centre off' - many of the pre-wired options don't come with that, and only a couple of my battery powered locos are wired that way.

Fine if you have the space, but IMHO not a fundamental necessity, the main reason being that absolute switch off is not a requirement, particularly with intelligent chargers - so without a CO switch, it's simply either / or

Might be different if you were to leave your loco out in all weathers - but we don't

I would only install a DPDT CO if the need is to maintain Battery and Track Power. That has nothing to do with turning the Battery on or off or the charging circuit that requires the battery to be off to charge. A Smart Charger will tell you if it is in Charge Mode ie off. Why a Centre Off? Well to stop any possible flash over, just a belt and braces thing really.