Model Trains

[andy3055]

That is one big advantage to using those motor driven switches. You can easily activate the signal lights from those.

The trees are great. I have seen some that look real when you go "down" to looking at that level! Some people do amazing things.

[tszaboo]

I've been trying to get back into the hobby. My father had a TT size system when I was a kid (well ,he has it now but it's all rusted). And I've bought a bit of Piko H0 kit last year. I've also designed and built a Raspberry Pi Pico based DCC turnout controller, and designed a voice decoder based on the RP2040.
I kinda have a working software for it, it can decode DCC messages, but not interpret them yet. I'm also considering whether or not I have to rewrite the protocol reception from circuitpython to C because I have performance issues with it. But the proof of concept was able to play MP3 and wav, and turn a DC motor.

Very interesting concept.

You do know they now make slow motion turnout machines with DCC controllers built-in?
Cobalt:
  https://www.dccconcepts.com/product-category/the-cobalt-collection/cobalt-point-motors/cobalt-ip-digital/
Tortoise:
  http://www.circuitron.com/index_files/Smail.htm

They are servo driven, I don't have a built track to use it. Otherwise I would probably DIY a servo for it.
Honestly, I've been even toying with the idea of making my own solenoid for it, since the bought ones are 25 EUR each.

[andy3055]

My collection of stuff did not have any RC turnouts and those are damn expensive.  I ended up getting some off eBay. They are different makes and I have to tweak them. Lucky I have the time, if not, it would be frustrating. One other thing is that older track seems to have a slight height difference from modern code 100 track.
Mark: For HO, what is the best wheel spacing you have found? I have one of those digital calipers with me.

[MarkF]

Andy:
  Here is the standard for HO wheel spacing
    https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-4.2_2019.01.04.pdf

  NMRA Standards and Recommended Practices documentation (everything you want to know and more)
    https://www.nmra.org/index-nmra-standards-and-recommended-practices

tszaboo:
  The TORTOISE™ Slow Motion Switch Machines and Cobalt Point Motors are not servos.  They are stall motors.  You feed them 12 DCV and they run until the gearing reaches the stop where the motor stall (reversing the voltage to goto the other end).

  Servo motors can be used to move turnouts.  mpeterll's youtube channel has an example of using servo motors but he says they are not still available.  I don't know what servo controllers might be available.
    https://youtu.be/Dcf1QiQL4YY?t=352

[andy3055]

Thanks, Mark.  That is great info.

Now, another question. I have used Moly grease on the axles of the locos and it is supposed to be plastic safe. Only time will tell! That stuff is dark grey in color. I have seen some You-tubers using silicone grease. which is white or colorless. That looks much better in color.

What do you guys use?

[MarkF]

Thanks, Mark.  That is great info.

Now, another question. I have used Moly grease on the axles of the locos and it is supposed to be plastic safe. Only time will tell! That stuff is dark grey in color. I have seen some You-tubers using silicone grease. which is white or colorless. That looks much better in color.

What do you guys use?

I can't help you on this one.  I haven't reworked any of my locos. 
Even my old locos don't seem to need anything done to them.  'Knock on wood!"

However, I would stay away from anything automotive as it is probably too thick and heavy.  You might try the model railroad sites. For example:  https://midwestmodelrr.com/assembly/lubricants/

LABELLE #106 Grease for the gearbox seems to be popular from a web search:
  https://labelle-lubricants.com/shop/labelle-106-grease-with-ptfe/

[andy3055]

Thanks again,  Mark. Since all my locos were not in use for so long, all the lubricants applied at the time of manufacturing has dried up. I am servicing them before I start to run them as sourcing parts like gears for these will be very hard.

[MarkF]

Labelle's how-to video is very instructional and I highly recommend it.
  Skip ahead to time 8:30 for HO scales.

 

[andy3055]

Thanks Mark. That is a wealth of info!

[pcprogrammer]

Slightly off topic, but worth the watch. Someone has been very creative in making this train system.

[andy3055]

That is amazing! In the 60s Meccano was the thing that was very popular. It is still in many ways. It is a lot of work and one can go crazy with ideas.

[pcprogrammer]

That is amazing! In the 60s Meccano was the thing that was very popular. It is still in many ways. It is a lot of work and one can go crazy with ideas.

Sorry for the really of topic, but each his hobby 

Very true. That is what I have at the moment with FisherTechnik. I'm working on some machine to pick boxes from a storage racks. Want it to be able to get a box, move it elsewhere and dump the content, a bit like what is shown in that video.

The first setup I made was becoming to heavy and impractical. So I'm taking it apart again but will use some of the idea's in a new setup. But that is for me the fun of it at the moment. Just try to build things and see if it will work as imagined.

The picture shows the build. It has four axes of movement. The pillar can rotate and has an up and down part.

[andy3055]

That is some serious work! I think Meccano has come a very long way and added a lot of stuff. Those days there were only so many things you could build with a set you bought. There were not many variations/options in each set.

[themadhippy]

think Meccano has come a very long way and added a lot of stuff. Those days there were only so many things you could build with a set you bought. There were not many variations/options in each set.

I'd say the total opposite is true,look at the sets available today,most are for 1 off models,then compare to  what was available in the 50's through to the 70's

[pcprogrammer]

think Meccano has come a very long way and added a lot of stuff. Those days there were only so many things you could build with a set you bought. There were not many variations/options in each set.

I'd say the total opposite is true,look at the sets available today,most are for 1 off models,then compare to  what was available in the 50's through to the 70's

You see this same thing with Lego (technic) and FischerTechnik. More and more parts are made specific for the models in the set and are less universally usable. But that is not to say that one can not spend many and many hours having fun with building stuff. 

[andy3055]

That is the point.  They have refined the parts and added things to the assortment.
But getting back to the  trains, here is a tunnel under construction 
Sorry, forgot to rotate.

[pcprogrammer]

It is a burger tunnel 

Love the little tree in front of it 

[andy3055]

I have to get the brick for the portal printed
More to come. Anybody got ideas about or against using PWM type speed controls on these small brushed DC motors? Someone on YouTube had mentioned that they are too hard on them and shortens the life span. Any ideas? Come to think of it, DCC controllers are not pure DC as far as I know.

[pcprogrammer]

I have to get the brick for the portal printed

Based on the initial setup I expected some paper mache type of construction. 

Anybody got ideas about or against using PWM type speed controls on these small brushed DC motors? Someone on YouTube had mentioned that they are too hard on them and shortens the life span. Any ideas? Come to think of it, DCC controllers are not pure DC as far as I know.

Not an expert, but I don't see why it would be a problem. RC servo's also use some form of PWM to control them. Only issue I had with the brushed motors in such servo's was the wear of the brushes due to going back and forth for tiny movements to often. Talking about cheap (3$) servo's where the motors did not have real carbon brushes but fingers instead.

The control systems sold by fischertechnik for their models also use PWM to control the speed. No issues there. The motors are also brushed types.

[fourtytwo42]

Anybody got ideas about or against using PWM type speed controls on these small brushed DC motors? Someone on YouTube had mentioned that they are too hard on them and shortens the life span. Any ideas? Come to think of it, DCC controllers are not pure DC as far as I know.

I found some of them quite vicious, not just the motors heating but also the wheel treads micro-pitting. Presently I am using fairly pure DC with a bit of 100hZ sine wave in it for slow running. In OO/HO I have nothing like the pickup problems I had in N-gauge EXCEPT some x-6-x steam chassis that have rubber tires on the center drivers and pickups only on the outer drivers, these are completely useless and stall frequently so I ensure I don't buy any more of those. I am running tank loco's so no tender pickups but the good makes have pickups on ALL drivers plus at least the leading or trailing bogie, those loco's have no pickup problems at all.
If you want to go PWM I would make sure to get a recommendation from someone personally, exhibition operators are a good source IMOP.

[dave j]

More to come. Anybody got ideas about or against using PWM type speed controls on these small brushed DC motors? Someone on YouTube had mentioned that they are too hard on them and shortens the life span. Any ideas? Come to think of it, DCC controllers are not pure DC as far as I know.

I found this page with reviews of various model railway controllers and discussion of heating issues. It includes oscilloscope traces showing their PWM waveforms. The site also has his own designs for several model railway controllers.

[andy3055]

Thanks.  I haven't checked it yet but seems like he went from PWM to analog in his designs.

[MarkF]

Anybody got ideas about or against using PWM type speed controls on these small brushed DC motors? Someone on YouTube had mentioned that they are too hard on them and shortens the life span. Any ideas? Come to think of it, DCC controllers are not pure DC as far as I know.

Now this is a tough one...

The evolution of model railroad controllers from DC was to increase the start and slow speed motor response.  They began primarily trying rectified AC and then moved to PWM.  There were a host of other waveforms tried.  I believe today that all DCC decoders use PWM to drive the motors.  Some DCC decoders are now also using the back-EMF for speed feedback in order to adjust the motor's response.

PWM for motor control can cause excessive heating in the motor coils and increase erosion of the brushes.  I remember when PWM first started being used that there was a big concern about overheating the motors.  The actual effects of PWM on motors is a mix of many factors.  Here are some resources on the theory:

Controlling Brushed DC Motors Using PWM

Sumida Crossing - DCC Motor Control - PWM

My understanding is that any motor deterioration due to PWM can be reduced by increasing the PWM frequency.  I believe the first controllers used a PWM frequency in the 60 Hz range (some tied to mains AC freq).  DCC controllers seem to be at 16 KHz (top of human hearing) and maybe higher for the newest using back-EMF sensing.

There doesn't appear to be a definitive answer as to how big the impact is to the motor lifespan.  However, PWM with H-bridges is pretty much the accepted way of controlling small motors.  The design of PWM for motor control has come a long way.


I keep seeing servo motors popping up in this discussion.  Servo motors are a completely different animal.  You send a PWM signal to the servo to specify its desired position.  But, that is the end of PWM.  Servo motors have a angular feedback mechanism from which a comparator drives the motor with a DC voltage in the forward or reverse direction until the angles match.

[andy3055]

Thanks Mark. That is  a great explanation. Probably the newer motors in those DCC ready locos are designed for the purpose. I think at this time it is best to stick to the older analog controllers as these old motors are hard to replace. Especially for Hornby and Fleishmann, parts are very hard to find.
Thanks again for your input.

[MarkF]

Be aware that a lot of those old analog throttles actually injected pulses as shown in the link davej provided.

If you're up to building something here's a hacked together throttle from online circuits.  Since it's rectified AC, you would get the slow speed start characteristics without the ill effects of the sharp edges of a PWM waveform.  It would be a nice compromise.

(Select R1 to set the maximum track voltage.)