An 0-4-0 loco from card - for the Skarffe Lt Rly - another vid Amazon PWM vs homemade

[teedoubleudee]

Fascinating article on DC controllers Jim (Link Post #18). Many many years ago I built my own PWM controller - sold it along with all my other railway stuff mis 80s, it was the size of a small house brick IIRC . I am using a mixture of DC and DCC on my new layout (no physical track connections please note!). A trusty NCE Powercab for the manual control and two shuttle controllers from Block Signalling. One of the Block Signalling controllers comes with built in DCC controller and the second one is a Simple DC module. This second one works in conjunction with a cheap PWM controller I bought from China a while ago for pennies. It is now available on Amazon here https://www.amazon.co.uk/ARCELI-Upgrade ... op?ie=UTF8. I have to say it works remarkably well driving a small modern 0-4-0 and five coal wagons very slowly on a short straight that includes a 1:40 incline.

[JimRead]

Hello TWD,

Many thanks for the reply good of you. The PIC controller looks very good indeed and I have ordered one thanks for the link.

I know where they got the circuit, from Jonathan Scott, like most designers he likes to put his stuff out there so that others may use it and some will be able to design something better. This is the page on his site: https://www.scottpages.net/PID675.html if you take a look at the PDF link you'll be able to see the circuit, a bit complex for me so I stuck to the one on #18. Jon's design has also got programmable 'inertia' built in.

It will be interesting to see how it works, it will not be any better at the control but maybe quieter due to the high pulse rate at 16 Khz as opposed to 100 hz.

I will do a video of it when it arrives, I noticed that my video on #18 is a bit jerky, I had to reduce the 50 fps output from the camera to 25 fps using Handbrake. Then I vaguely recalled a firmware hack, the camera is a Panny GH1, and I found Mr L.Powell's 75Mbps Peak Reliability Setting Hack, which I downloaded and installed, the camera will now do 1080p @ 25 fps

I'll do that vid again this afternoon it will be interesting to see the difference.

Cheers - J

[JimRead]

Hello all,

This is my second video having not been very happy with the first one. I've done a hack on my camera from television quality to film quality.

Incidentally the camera a Panasonic GH1 (with the hack) was the first DSLR type one to make a feature film, recently bettered if you can call it that by a bloke with an iPhone 5

Anyway here's the new video
https://www.youtube.com/watch?v=jLd0Z1B9W0E

Cheers - J

[Bandit Mick]

Enjoyed your you tube video a lot Jim - very informative. If you can make such a sensitive controller on the cheap, why is it at exhibitions that layouts are often controlled by all sorts of wizardry and fancy controllers and locos go hurtling around and end with a final undignified bump into the stock they are coupling onto. Plus no matter how fancy the controllers and how many electrofrog points and switches are used, a big hand often appears to give a little nudge?

[JimRead]

Hello Mick,

Thanks for the nice comment good of you. I often look for the fleet of model ambulances on the layouts I see with skull cracking stops and starts, not that I've ever said anything, of course.

I think it's because the easiest route is to buy something, developing an extra skill is ignored.

Sakura Systems in NY sell two power supplies and a stereo amplifier for $5,100.00 'Hi End HiFi". Errrrrrrr! well!! the bit that does all the work is an LM3875 chip £5 each.

I made one for about £80 the transformers are about £25 each, so few components that a PCB is not needed. The 'Hi End' for peanuts and only because I'd taken the trouble to learn how to make an MR controller in 1979 and found out what the components look like and then being able to turn a simple circuit diagram into something that works.

Thinking about it though there is another reason, motors, a commercial controller must be able to power anything from a 3 pole to a coreless, from N to 0 with no danger of burnout.

It doesn't matter what the pastime is the gullible will always be ripped off. My main ones are photography and audio the snake oil in both is hilarious.

Cheers - J

[Mountain Goat]

Just a question. The feedback will send maximum voltage of something like 12 or 14 volt spikes, be they a square wave or a peak V shape wave etc., and sends enough of these pulses to act like a certain voltage to power the loco. I have noticed when I had two Gaugemaster hand controllers in the past andone had feedback, very little difference between the two until one comes to gradients. Going up the feedback controlled loco was less likely to slow down as it pulled its load up the incline unlike the non feedback conteoller. Going down, the feedback controller kept the loco at a steady speed while the non feedback controlled train started to run away from me at speed.

But with non feedback controllers, I have also noticed that standard mains powered versions can be jerky at slow speed and the locos or whatever (Minidrill etc) do have a bit of a humm when running, which I assumed it to be the motor (As it was the motors that hummed).
But if I ran those motors directly from my car battery, they ran quiet and smooth even if flat out, and I have had this same experience with my home made controller on testing which runs from a small 12v sealed leasure battery.
I have not experimented enough to see if I have jerky starts or not because my concentration was in getting the controller itself to work, so I would imagine that I may have to give trains an occasional shove. It is hard to tell at the moment because those little 0-4-0's take so little current that I need to add some extra resistance to the controller part of the set up so I can bring the locos to a slow speed crawl, and I will be doing this with a switch so I will have switchable extra resistance as some locos do not need this. (I still aim to keep the controller simple).

But it is interesting to notice the different effects of what we assume to be "A controller" and yet in reality they all bring different qualities to the ride of the loco according to how they are made.

[JimRead]

Hello MG,

Very interesting message thanks a lot. If you do want to read comments from an expert please go to: https://www.scottpages.net/ReviewOfControllers.html

I'll do my best but I am not an expert.

Ramping voltage controllers; poor starts/stops, very quiet.

Pulse controllers; slow starts/stops better but noisy

Pulse plus feedback controllers; slow starts/stops and maintain the set speed but noisy.

All three can be made very cheaply using simple circuitry. This is my raison d'etre a skill learnt can be used in many ways.

I only ever bought one commercial controller in 1979 it was rubbish for what I wanted.

Cheers - J

[JimRead]

Hello TWD and Hello all,

The PWM arrived and I've done a comparison video here.
https://www.youtube.com/watch?v=yBY-7xNuLNA

Sadly the PWM does not have any feedback and will not go slowly, well the slowly I am used to and the take off point is erratic.

This as they say is what you find.

Cheers - J