dcc (again) tiny decoder.

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mattinair
Posts: 222
Joined: Wed Feb 11, 2015 10:02 pm
Location: Sebastopol California

Re: dcc (again) tiny decoder.

Post by mattinair »

Toy train wise I'm reasonably good at things like the color of dirt but this do it yourself electrical stuff is really Greek to me...
I look forward to the day when all this stuff (dcc, switches, steam locos etc.) will be available to a retail buyer like myself....Looking at the prices payed for some of the stuff in other larger scales.....well....money's no object..

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

I've not vanished, but it's slow progress, I've relocated two of 6 wires on the dcc decoder and I'm waiting for a booster and encoder to arrive.
I've got a RPi2 setup with a skinny Debian install and JMRI on it.

Some tweezers to hold the stupidly small decoder in the clamps of helping hands is pretty much all I need.
I can't wait to show you guys a t train running on dcc.

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

With a slight sadface, I think I've fried my decoder.

I did see it briefly with decoder pro, and it was able to tell me its settings, but after i disconnect it from the test loom i was using and bonded it to a train's power rails it was no more in evidence and I've not seen it report anything since.

I suspect my eager stripping of the motor outputs MAY have lead to a brief short. *oops*.

I've ordered another decoder to see if i can be a little less hamfisted with it.
It's annoying because I'd successfully relocated all the wires to sit at 90 degrees to the board rather than 0.

I'll prove the concept on the train with the new board before I bother to rejig the wiring to fit in the chassis :/

Sorry the updates are slow on this project, I got married.

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dkightley
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Location: Nottingham, UK

Re: dcc (again) tiny decoder.

Post by dkightley »

You mean to say you've let a simple thing like getting married get in the way of important T gauge work??? ;) ;) ;) ;) ;) :roll:



Congratulations on having tied the knot. I hope the day went well...and wish you and your good lady good fortune for the years to come. :D :D :D :D :D :D :D :D :D :D
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

martink
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Location: Melbourne, Australia
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Re: dcc (again) tiny decoder.

Post by martink »

dkightley wrote:Congratulations on having tied the knot. I hope the day went well...and wish you and your good lady good fortune for the years to come. :D :D :D :D :D :D :D :D :D :D
Er, Doug, last time I checked, Caitlin is traditionally a woman's name... perhaps time to make use of the embarrassed smiley?

Anyway, congrats,and I really am curious to see how the DCC approach works out. That is an avenue that I never even considered attempting. One very nice feature about T is that there is still room to pioneer things and try something truly unique.

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

I'm using a sprog 3 and JMRI with black and red wires connected to the bogie and orange and grey wires connected to the motor.

When i read and write values to the decoder the motor does little glitchy movements so electrons certainly have the option of getting places.

After I've read and set some values in the decoder I then open a "throttle" and wiggle something and exactly nothing happens.
I've been reading pages of JMRI docs and watching youtube videos and can't find a single thing that actually tells me what to press in what order to make a train go backwards and forwards.

Would any of you spiffing chaps have the faintest idea what I might be missing from my understanding.
I'm unsure if I need to change from "programming" to "running" mode or something or quite what. :/

caitlin
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Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

Pretty standard, I expect, but all you have to do is make a public post on a forum to embarrass yourself, then clean your track discover that you have appalling power pickup, add bridging wires so you can pick up from front and rear bogies and you have a dcc t-gauge train.

https://vimeo.com/145782582

The wiring I've done to achieve this is revolting so now I have to start the mammoth task of trying to get the hardware *inside* a chassis rather than trailing around in mid air.

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

A slightly different, more exciting (to me) video would be:

https://vimeo.com/145865800

I've had to drop the lighting out of the ICE unit, but I have two functions on the DCC board remaining and I have hopes of getting lighting back.

Thing I have to figure out now are:
"how does one run a multi-unit train with dcc?" Which I assume is just to set the dcc units to the same ID number and hope they all pull the same.
"how do you actually make model scenery?" :P

martink
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Re: dcc (again) tiny decoder.

Post by martink »

You have actually managed to squeeze a decoder into the vehicle - I am officially very impressed.

In the larger scales, some model locos do have two motors working off a single decoder (the Heljan OO Garratt for example). My best guess is that as long as the motors and mechanisms are reasonably well matched, you would lose a bit of (potential) fine control but otherwise things would be fine. And seriously, even without DCC, with two or three motor units per train we do get a bit of slipping and lack of synchronisation anyway and yet that doesn't cause any problems. Another important factor for you to consider is the poor pickups on T gauge locos and their vulnerability to dirty track and wheels - even more important for DCC than DC. If you have two power units sharing the same decoder then that means wiring them together and hopefully sharing more pickup wheels which will greatly improve overall reliability. That would more than compensate for any potential sync issues.

As for scenery, assuming that is a serious question ;) , there are lots of techniques, and it is much the same as in larger scales. Browsing some of the layout threads here would show you several approaches. I personally tend to favour the corrugated cardboard + plaster bandage + paint + scatter process.

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

I've ordered some points, and I have a servo.

I've figured out how to get the JMRI sensor screen to flip from inactive to active when prodded on the Raspberry Pi's GPIO pins.

I think I'm going to try and make an end to end layout rather than a goes round and round one, with a couple of loops in the middle to make it more "wheee".

If I can get end sensors working and can control points with a servo, I think I can get a "timetable" running from one end of the layout to the other with two or three trains doing things.

Why does it take so long to make decisions only to then have to wait for the post when one has made up her mind?!

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

Visiting the lighting situation again in the ICE trains I spent an hour trying to trace the little circuit board which is so fiddly and given I have quite meaty multimeter probes it's pretty hard to figure out what's connected to what, it's a double sided board with at least one resistor on it, a three pin diode thing and a couple of other components.
I've almost zero idea what they're *for* because two of the wires go straight through the board to the lighting board.

Anyway, this is all digression. I detached the board from the led cluster and tried the pins with 3.3 V, leds lit up. Knowing that LEDs are diodes and have some reverse voltage resistance potential I ended up wiring them together in parallel, opposing each other.

I've then welded them into my embarrassment of a test loco:
Image
and run it up to 50% speed in JMRI which is fast as I ever intend to take these locos, it seems to keep them below 5V on the motors that way.

If I can get my head and iron around stripping and soldering the enamelled wire I have then I should be able to get the light cluster back into the more beautiful loco I have running dcc I linked a few posts back.

I'd have loved to get them onto the extra wires from the dcc controller which are switchable power sinks, but I have no consistent DC supply in these trains, it's ac on the red and black and the DC that hits the motor obviously turns off, flips polarity and changes.

I think I might have murdered my raspberry pi though by stealing volts out of its headers, I expect I pulled too much current or something. I'm pretty bad at electronics when all's said and done.
Anyhoo, thanks for reading. Any and all comments about what I'm up to are welcome.

martink
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Re: dcc (again) tiny decoder.

Post by martink »

At a guess, the lighting unit circuit would be something like this... I also don't know if it uses a single bi-colour LED or two separate red and white ones.

The first thing to try (if you haven't already) is just connecting the white and yellow wires directly to the lighting unit. If these outputs are both push-pull types (alas, never specified in the documentation), then everything should work properly.

Unfortunately, if the 6-pin decoder is built the way I suspect it is (with open-collector outputs), then I cannot see any way of operating this type of lighting unit properly in bidirectional mode. Unless, of course, you are willing to seriously modify the lighting unit by isolating and completely separating each LED, and that only if there really are two separate LEDs. However, you can easily set up basic unidirectional lighting so that one of the LEDs works correctly - white on one power car and red on the other. This simply involves connecting the yellow and black wires to the unit on one car, and white and black on the other, and swapping them around until you get the right combination. This will give you correct, steady head- and tail-lights when running in one direction, and no lights in the other.

Image

caitlin
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Re: dcc (again) tiny decoder.

Post by caitlin »

There really isn't room to do anything much with the lighting unit.
I've also realised that the BR units I also want to run are on a 16M unit which has almost zero space for the decoder.
I'm a bit dejected tonight.
However I did manage to tin some enamelled wire and loom up the lighting unit for bonding to its little motor.

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

I hope this thread isn't too damnably boring for anyone who reads the forum, but i achieved this:

https://vimeo.com/146945663

lights do the right thing in each direction!

I need to get the little panel back on the bottom of the nose to lightblank the spill from the red, but it's all on the inside! woo.

Reith01
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Joined: Thu Jul 30, 2015 3:34 pm
Location: Sussex.

Re: dcc (again) tiny decoder.

Post by Reith01 »

This is remarkable!

Just a thought. If a train is going to be run as an EMU (permanently coupled) would it be possible to fit the electronics in an adjacent coach then thread the feed through with litz wire? (Fitting the coach with pick-up bogies).

caitlin
Posts: 23
Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

don't panic, in trying to get the wiring better seated for a closer shell fit so the slam panel would go on the nose perfectly i shorted something and evaporated two springs.

I shall order some more and press on :D

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SmallCentral
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Re: dcc (again) tiny decoder.

Post by SmallCentral »

Bravo 8-)

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dkightley
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Re: dcc (again) tiny decoder.

Post by dkightley »

I've been watching this thread with great interest....and I'm amazed at how you've been able to get so much into such a small space.

There's got to be a dcc manufacturer looking at this....as I'm sure dcc will generate a lot of interest in the scale.

Keep up this amazing work......
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

caitlin
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Joined: Sat Jul 04, 2015 4:58 pm

Re: dcc (again) tiny decoder.

Post by caitlin »

What I really need is for CT to sponsor me, since I exclusively use that single decoder of theirs.
There's actually LOADS of room in the ICE chassis if you have steady enough hands for the wiring.
It's really ALL about the packaging on the wee boards.
I wish I could afford the BR train and start figuring out how to get a board in that, I think it's going to need a dremel and some cleverness for that *that* guy.

Whilst I'm bleating about things though, both coastal dcc and tguage.com have been awesome at posting me things quite quickly.

Ozrail
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Joined: Wed Nov 20, 2013 10:50 pm
Location: Queensland, Australia

Re: dcc (again) tiny decoder.

Post by Ozrail »

Maybe one day Someone will develop a Decoder chip so tiny, it can fit on a paperthin circuit board like this one. http://www.bestpcbs.com/products/extra-thin-pcb.htm
And it can simple sit flat on the top of the motorised chassis where the electrical straps are.
Check out my Shapeways store for T-gauge stuff.
Image
http://www.shapeways.com/shops/everythingtgauge?s=0

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