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Author Topic: Sound decoder in wagon?  (Read 308 times)

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Offline Danielmc1

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Sound decoder in wagon?
« on: November 07, 2019, 02:19:46 PM »
Iím in the process of converting an old Poole Farish 61xx for DCC. Sadly there is no space for a sound decoder in there, but Iíve easily managed a Zimo MX616 (no sound). So my idea is to fit a separate sound decoder into one of two or three Dapol coaches fitted with pickups (usually intended for the LED strips).

I would however like the option to pull a short train of three or four cattle wagons with this loco and wonder what the scope would be to fit a sound decoder into one of these instead? Iím guessing principle hurdles are fitting pickups, changing wheel type and weight...?

Anyone successfully done this...?
« Last Edit: November 07, 2019, 02:22:31 PM by Danielmc1 »

Offline msr

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Re: Sound decoder in wagon?
« Reply #1 on: November 07, 2019, 02:33:40 PM »
Paul at CRSignals has successfully done this for me and it works really well. It was a Farish autoballaster that was used.

Offline njee20

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Re: Sound decoder in wagon?
« Reply #2 on: November 07, 2019, 02:38:43 PM »
My concern would be how to get the loco to move off and stop at the right time, given most sound decoders include a bit of "start up" and what not, if the decoder was in a coach/wagon they'd be out of sync, unless you actually wired through to the motor of the loco. You could do it with a 2-pin plug, or 4 pins if you want to use the loco pick ups too. I suspect it could be done with a lot of tweaking of loco CVs. Perhaps @msr has insight on how his is set up (albeit for a diesel I presume).

The 'chuffs' would also be out of sync with the motion of the wheels.

Offline msr

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Re: Sound decoder in wagon?
« Reply #3 on: November 07, 2019, 02:56:00 PM »
In the case of the autoballasters I run them with diesels. I am happy with the ESU LokSound that Paul uses by default. Their CVs can be easily adjusted to match the locos. I generally use a LokProgrammer but one can also enter the chosen CV values manually or using the JMRI software. These values work well for me:
CV2 (start) = 1
CV3 (acceleration) = 130
CV4 (deceleration) = 240 (max)
CV5 (top speed) = 255 (max)
CV6 (mid speed) = 127
CV63 (volume) = 100
They can individually be increased or decreased to taste. All the others CVs are at their factory default values.

Paul often sells brake vans with decoders and capacitors fitted, the latter helping smooth the passage across uneven track and pointwork. The pickups are created by tightly winding copper wire around the wheel axles and then loosening slightly.

I have also added sound decoders to coaches for running behind steam locos and these seem to work fine too. The chuff rate can be adjusted with:
CV57 = 30
CV58 = 3
The values depend on the steam loco - in this case it was a Farish Black Five. Somewhat higher value were needed behind other steamers.

Offline Danielmc1

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Re: Sound decoder in wagon?
« Reply #4 on: November 08, 2019, 12:50:43 AM »
That sounds more promising than I thought it would, although those auto Ballasters look a lot bigger than a cattle wagon which would help a lot I guess.

Connecting to the motor through two pin/wire is a good shout on a fixed formation (or auto coach) however my proposed layout will be end to end and I would like to run this Prairie around a short goods train so I suppose Iíll have to go down the route of tweaking CVís to match as much as possible.

How much did CRSignals charge, MSR?

I found these:

https://scalology.co.uk/products/pickup-springs-1-5mm-axle-for-p4-n-gauge-48-pack?variant=37017682696&currency=GBP&gclid=EAIaIQobChMIybqqq6_Z5QIVw7TtCh1ZPgxHEAQYASABEgLNpvD_BwE

...and have found metal truck wheels on ebay although I confess I know nothing about how to swap wheels or even which type to buy. Presumably any metal wheels/axles for sale must have one wheel isolated anyway or theyíd be pointless??

Offline msr

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Re: Sound decoder in wagon?
« Reply #5 on: November 08, 2019, 07:58:31 AM »
CR Signals can be contacted here:
https://www.crsignals.com/contact-us

Offline njee20

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Re: Sound decoder in wagon?
« Reply #6 on: November 08, 2019, 11:53:38 AM »
...and have found metal truck wheels on ebay although I confess I know nothing about how to swap wheels or even which type to buy. Presumably any metal wheels/axles for sale must have one wheel isolated anyway or theyíd be pointless??

You need the right size, they're not all the same, but yes, they will all have one insulated wheel as you say.

Offline Danielmc1

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Re: Sound decoder in wagon?
« Reply #7 on: November 15, 2019, 01:32:33 AM »

Iíve managed to change the plastic wheels on a Peco cattle van to Farish metal ones, used conductive paint to connect one wheel and the axle and then a dcc concepts axle pickup. Iíve installed a Zimo MX649 with maxi sugar cube speaker and SACC16 stay-alive.

First issue is the pickups are very intermittent - I was hoping the stay-alive was going to take care of this but it doesnít seem to be doing much, so more experimentation is required here.

Second issue - the F number sounds work (Iím amazed how good the little speaker actually sounds!) but unfortunately when I accelerate and brake Iím not hearing chuffing or brake squeal. I do hear steam hiss when moving off and some sort of brake judder, presumably when the loco is supposed to come to a stand, but the running sounds are definitely missing. Reading other posts, it suggests sound decoders require at least a resistor on the motor connections, so Iíve connected a 10k resistor but this hasnít made a difference. How did you guys get around this??

Third issue - JMRI isnít reading the MX649. I tried to write a new address which it reported an error, but did in fact write it. Reading around, I think this might be down to not having a motor as well.

Offline njee20

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Re: Sound decoder in wagon?
« Reply #8 on: November 15, 2019, 07:55:36 AM »
Yes, the inability to read/write will definitely be due to a lack of motor, however the resistor over the outputs should work. 

Online Nigel Cliffe

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Re: Sound decoder in wagon?
« Reply #9 on: November 15, 2019, 08:21:14 AM »
Yes, the inability to read/write will definitely be due to a lack of motor, however the resistor over the outputs should work.

That will fix the ability to read/write (needs to be nearer 100 ohms - 10k is not going to be useful for decoder acknowledgement pulses on programming track).    But the resistor won't fix the fundamental issue of no chuffs.

The standard setting in the decoder for producing chuffs uses the back-emf from the motor as it rotates to determine motor speed, and from that the wheel rotation speed.  A resistor doesn't behave the same way.    So need another solution.   
The ones which may work are either an axle rotation sensor (hall effect switch and magnets on rotating axle shaft, or a disk with an optical switch through a slit in the disk), or to turn off the decoder's attempts at synchronising sound with movement. 


(frankly putting an expensive loco decoder into a cattle wagon for just sound generation makes no sense to me ).


- Nigel


Offline pauliebanger

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Re: Sound decoder in wagon?
« Reply #10 on: November 15, 2019, 05:14:14 PM »

Second issue - the F number sounds work (Iím amazed how good the little speaker actually sounds!) but unfortunately when I accelerate and brake Iím not hearing chuffing or brake squeal. I do hear steam hiss when moving off and some sort of brake judder, presumably when the loco is supposed to come to a stand, but the running sounds are definitely missing. Reading other posts, it suggests sound decoders require at least a resistor on the motor connections, so Iíve connected a 10k resistor but this hasnít made a difference. How did you guys get around this??


You can get any ZIMO sound decoder to 'chuff' and indeed play all background or automatic sounds (like the brake squeal when stopping or random coal shovelling if it's part of the sound project) without a motor or resistor or wheel rotation sensor.

Obviously, there will be no direct sync to wheel rotation, but it will vary in speed according to the position of the throttle.

Nigel has already pointed out the general idea, turn off BEMF. Specifically, CV58=0

Best regards,

Paul

Offline Danielmc1

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Re: Sound decoder in wagon?
« Reply #11 on: November 18, 2019, 11:27:00 AM »
Nigel & Paul, thank you!

100 ohm resistor did the trick - I can now read and write to the decoder and now CV58=0 the sound is responding to the throttle which is great.

So this leaves me with two things still to do. First is matching the acceleration settings in the decoder in the loco to the sound decoder in the wagon. Second is to improve the pickups in the wagon. I have three of these livestock wagons so I reckon I might try fitting identical pickups to the other two and permanently link them with thin black decoder wire. Maybe a bigger capacitor on the stay-alive may help as well?


Online Nigel Cliffe

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Re: Sound decoder in wagon?
« Reply #12 on: November 18, 2019, 04:36:44 PM »
The resistor should be a temporary item, not whilst running.  Otherwise it will get very hot. 

Rough calculation on a typical 1/4W resistor, at 100ohms, and nominal 10v DC running through it:  Current is 10/100 = 0.1A.  Watts = 10*0.1 = 1W, or four times the rated power of the resistor.   Not good for it, or any plastic in the vicinity.   


Offline Danielmc1

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Re: Sound decoder in wagon?
« Reply #13 on: November 18, 2019, 06:45:11 PM »
At present I have a half-watt resistor on it. When Iím done with programming, am I ok to simply remove it and protect the motor wires from shorting?

 

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