Cheap controller - your views?

[Neil McGrath]

I have used some similar boards and they all seem to work well. I do suggest that you power it with a short circuit protected power supply that is not too powerful. A 1 Amp PSU should be plenty. If you are not too sure of your PSU you could add a cheap voltage regulator board that can provide the necessary protection and provide a stable voltage to the controller.

[clayliner]

Alan Hamer (who, unlike me, understands these things) has now assembled one of these controllers from the component parts as described by Trevor and preliminary reports are very positive. He has a test track with digital displays showing the current and voltage for any combination of motor/loco and controller which is very useful.

I am hoping he will post some of his findings here in due course for the benefit of all. Our future TLO might want to talk some more with Budget Model Railways.

David.

[Stefan Krebs]

I built a cheap controller following the instructions in a 1980 Model Railroader, and it outclasses all model railway manufacturers' controllers. Cheap is not necessarily bad.
I just started a multi-part reply in the thread "Old controllers - new motors = problem?"; and I'll cover the PWM versus coreless question there.

PWM in the audible spectrum (12 to 27 000Hz) can cause a nuisance as you hear the 'rattle', but that doesn't mean that outside this spectrum it's all fine; just because you can't hear it, doesn't mean there is no damage  happening.

[Hochwald]

An interesting discussion. Firstly to lay a myth PWM contollers will work with coreless motors. According to the Laws of Physics, specificallly Maxwells laws of electromagnetism, there is every reason why they should. In fact ariel drones use coreless motors with PWM control, DCC loco use PWM as well and they seem to work OK. I've built one of these Budget contollers and I tested it against Minitrains and Gaugemaster controllers at the Dorset Members day last week. In simple terms there was no observable difference in performance between it and the Minitrains but there was a slight difference between these 2 and the Gaugemaster. Only to be expected as they are different technologies. All these devices ran old open frame motors, modern small motors and a tiny coreless motor without problem drawing virtually the same power with each different motor. The Budget Contoller has a centre off DPDT switch to control direction and the potentiometer has a click off as well so it shuts down completely to stop a loco.

However compared with older motors coreless motors have a very low rotating mass so effectiviely have no flywheel. This is why they respond to control changes so quickly and why if you want more realistic locomotive control with a degree of inertia you need to fit a flywheel. An overload cutout would be a good idea but if you use a low output transformer, say 1000ma, or one giving less than 12v the controller cannot put out more than this, which would protect most motors. For the money it would be hard to go wrong. I have no connection with Budget Model Railways other than as a satisfied customer.
   

[B.Meldon]

One problem I have observed with some of the cheaper controllers and older type locos is that they will not start the locos at slow speeds. You have to turn the speed up higher to get the loco moving and then turn it back down again to get the loco to run at a slow speed. This is ok for a circuit layout but useless for shunting.

Brian Meldon

[Stefan Krebs]

Hochwald, Du hast recht! Yes, you're right!

However, high frequency has other effects, think high-frequency welding. So, while PWM and coreless may work together fine, there might be implications. And of course, the same applies with regards to ANY motor, not just coreless.

As I said, I'm working my way through the technicalities, while trying to keep it simple. But I chose a different thread to debunk the myths (look at old controller - new locos = problems? in this forum).

This thread is about our views on cheap controllers, and I stand by my statement: cheap can be brilliant. My DIY controller cost about

[B.Meldon]

Brian, there are 3 potential reasons for engines not being able to run slow:
1.   Cheap motors with high magnetic resistance, combined with insufficient gear ratio. Take the motor out and turn it by hand; if it 'snaps' from pole to pole, i.e. doesn't turn smoothly, it is one of those (practically all older 3-pole anchors will do that, but it should not require much force; take an old Fleischmann H0 pancake motor and its clone, the Lima pancake motor, and you will notice the difference).
2.   Insufficient gearing (the Minitrix dock shunter {=T3) is an example of that).
3.   A controller that does not regulate down to zero (most commercial transformer-controllers jump from 0 to circa 2V before commencing a 'smooth' voltage rise, older Maerklin transformers jump to circa 6V!!!).

Ei gude wie vom
Waldschrat ;D

I think you have missed the point.

It is not that the chassis will not run slow, it is that they will not start slow. 
The problem it is getting the locos moving from stopped.
The controllers involved do start from a low voltage it is just that the locos do not move until they are turned up higher.
Once the locos are running the controller can be turned back down and the locos will run slow.

I have seen this happen with these cheep controllers and others.

In regards to the older open frame motors it is perhaps worth mentioning that the vast majority of 009 locos use these older type of motors, it is only chassis made in the last few years that do not.

It is quite easy to get a cheap controller to work well with these newer motors.
It is also quite easy to get a simple controller to work well with the older motors.
However, it is virtually impossible to get a controller to work well with both types.

Brian Meldon

[Stefan Krebs]

Dear Brian,

Maybe you're right, I don't have the full facts, of course cheap can be cheap & nasty, but so can expensive. ???

But then again, I can repeat only what I said before: this thread is about our views on cheap controllers, so we don't have to agree: you have your views, and I have mine. ::) ::) ::)

That said, I stand by my statement:
Cheap can be brilliant; (and expensive can be cra