Analogue controllers?

"Stimpy" wrote

Gaugemaster do a nice range of hand-held controllers along with complementary transformers.

The appropriate codes are as follows:-

HH - hand-held with feedback W - hand-held without feedback WS - hand-held (without feedback) with simulator.

With modern locos and control equipment I doubt you'll need the simulator. I'd go for a basic 'W' with the appropriate transformer (T1 from memory).

If you can't get them locally I can supply.

John.

When I still lived in England I had a Gaugemaster inertia controller.

I can thoroughly recommend their products, but I found the inertia simulation a waste of time on a small layout because there wasn't enough room to use it properly. And shunting was well nigh impossible.

I got the best and smoothest control using it in a way that wasn't intended by the manufacturer: with the throttle full on, using the brake for speed control.

I would second what John has said - a non-inertia, non feedback Gaugemaster handheld. In 2mm scale you might run in to small coreless motors and you don't want a feedback controller when using them.

Jim.

I'm puzzled by the advice not to use a feed-back controller on a shunting type layout! Other than with coreless motors, where the amount of feedback will be wrong as compared to normal motors, this situation is precisely where feedback is most useful in keeping slow moving locos moving. Is there something seriously wrong with Guagemaster controllers???? Can they not be adjusted to suit coreless motors??

Regards, Greg.P. NZ

"Greg Procter" wrote

controllers???? Can they not be adjusted to suit coreless motors??

There's nothing at all wrong with Gaugemaster controllers, the problem has historically been with the quality of motors fitted to British N-scale stock.

How on earth do you adjust ANY analogue controller to suit ANY motor? That's a whole new concept to me.

John.

I have an ancient Compaq suitcase portable, with a couple of expansion cards from Realroad, with an analog to digital converter driving a voltage regulator. The software allows the optimum waveform to be generated for any motor, as well as going from zero to a smidgin less than starting as soon as the control knob is touched.

I don't use it any more.

OK, that makes sense - or not ;-)

The feedback controller reads the voltage generated by the motor during "pulse windows". (ie the 'off' time of PWM) The set-up of the controller circuitry boosts the following output pulses in reverse proportion to the motor voltage sampled. For inefficient motors the voltage generated might be only 1-2 volts at average speed and barely detectable at shunting speeds. Highly efficient coreless motors might generate 5-6 volts at average speed and a volt at shunting speeds. Depending on the sensitivity of the feedback circuitry your N gauge motor might cause it to boost the output voltage to maximum while the coreless motor will cause it to minimise the output. Adjusting feedback can be as simple as adjusting pairs of resistors so the feedback circuit "sees" a suitable voltage. Depending on Guagemaster's circuit it probably needs a double pot which adds to the cost and there's the question of whether operators would set it correctly.

Greg.P.

Just found this from a month ago - I thought I remembered the discussion but it was a lot closer in time than I thought. :-)

It will probably save Nigel Cliffe joining in again :-)

Jim.

The Pentrollers had a switch for 3 different types of motor, 2 Portecap types & non. I've never owned one but those that do swear by them. Not sure if still made though.

Kevin Martin

They have not been produced for some years. S/hand examples now sell for quite high prices on Ebay.

They were a good design in their day, still work fine. But modern electronics could do better.

Suggested controller, but over £100 - Uhlenbrock Daisy System. DCC or Analogue from same controller (not at same time!!), with user-setup of the behaviour for coreless motors on analogue. A friend has one and rates it better than Pentroller on analogue.

- Nigel (Pentroller owner, and friend of Stewart Hine who made them).

On Sun, 30 Dec 2007 23:16:51 +0000, Greg Procter wrote

Could I ask another dumb question? What *is* feedback in this context? When I was last modelling, controllers were either just speed controllers (i.e. the H&M Clipper style) or had inertia simulation.

Thanks for helping me get (re-) started :-)

You could buy a Gaugemaster Combi which is a simple, but good quality controller or even use those controllers that Bachmann/Graham Farish provide in their train sets, although neither of them have inertia or braking. I use two of them on my small N gauge layout and they are very good considering how much they cost.

Fred X

The controller outputs pulses and reads the track voltage (ie motor generation voltage) in between. If the motor generation voltage changes suddenly then the controller adjusts it's output in the opposite direction. ie if the motor stops revolving there will be no generated voltage and the controller will increase it's output until it detects a voltage being generated. If the motor speeds up then the controller lowers its output.

On Tue, 1 Jan 2008 01:45:05 +0000, Greg Procter wrote

Thanks for that but what *use* is it in real terms? How does it effect the 'user experience'?

When I tell the controller to make the train go in one direction, how does 'feedback' affect what actually happens? Presumably the train still goes in the direction I want it to?

Sorry if that sounds a bit dim but I guess I'm not too fussed about what goes on in technical terms, rather how it affects the running of the trains :-)

The train speed will remain approximately constant, unless you change the control, regardless of ascent/descent or track friction on tight curves. Starting from stop can also be smoother (the controller will apply the extra power necessary to overcome stiction).

Mark Thornton

Perhaps you might be familiar with cruise control with cars. It has good and bad points. Very useful on a long drive where CC tries to keep your car moving along at the same speed without you constantly adjusting the accelerator. Not so handy in stop/start traffic.

CC is one form of "feedback" where it self monitors for relatively minor adjustments.

On it train controller you will similarly be able to set a given speed, it will continue up a modest gradient with no change of speed. Once over the top it will not sprint away down the grade. Compare it with a non feedback controller, then you will understand. Like CC the effect is much more apparent on a largish layout.

Kevin Martin

"Stimpy" wrote

The originally concept with feedback controllers was an attempt to eliminate erratic running with the poor quality motors & methods of current collection which were prevalent in the 60s, 70s & later. Any interruption in supply of power to the motor or a change in speed of the motor would result in a correcting and temporary change in the amount of power being applied to the track.

John.

On Tue, 1 Jan 2008 14:15:20 +0000, John Turner wrote

Got you... makes sense now. Thanks all!

There are _two_ main uses for "feedback control".

My use is to keep small shunting locos from visibly stalling while shunting at very low speeds. A big flywheel would achieve the same effect, but often better quality models operate at about 99% of the standard I demand and so a complete mechanisim rebuild doesn't seem warented.

With feedback control in DCC decoders the ability to run trains at constant speed up and down hill seems to be stressed. That seems to me to be a useless attribute (can an attribute be useless?) as I expect my steam locomotives to vary their speed under different conditions.