Hi All
I was given a new Hornby R965 controller for a xmas present. It seems to give quite good slow running for most of my locos (except the 20 year-old Lima ones).
On putting my multi-meter across the rail supply, it gives a steady voltage reading regardless of the knob's rotational position. From this, I deduce that it's a current-controlling device ? (My meter peaks out at 250 m.amps)
For the big Lima diesels, I need to use their train-set supplied controller (one of which only goes to '2' out of '5' power settings !) I can use the Hornby unit on these but it needs almost full power before the Co-Co shoots off at speed...
It would be nice to have one controller that does all properly (I do mostly shunting and slow-running). I have considered changing the pancake motors in the Lima stuff (eg DMU, Big Co-Co) for 5-pole ones ?
Generally, the 009 line is satisfactory - most of the problems are on the 00 (standard gauge) lines - there's a moral there somewhere.
Any ideas welcome[/b]
The old Lima stuff was always bad to control so nothing new there. If you replace the motor you'll solve your problem. I've had the odd Lima N gauge chassis in the past but just got rid of them, they are not worth the effort.
Regarding control of N and OO locos for DC personally I'd get rid of your Hornby controller (yes, I know it's new) and invest in a Gaugemaster unit. The W if you want to have a hand held unit or 100 for a cased version. The W will control both N and OO locos but you need to make sure you get the right cased untit that says it's suitable for N and OO, some of theirs are made for O scale which wouldn't do. There are other makes as I am sure someone will point out, but Gaugemaster are known to be reliable and give good performance and their guarantee is second to none.
With controllers you get what you pay for, if you want to shunt you need a decent controller.
I'm afraid I don't have suggestions to tame the Lima diesels, but regarding the Hornby controller I suspect it gives pulsed output (confirmed on this excellent web site -
http://www.scottpages.net/ReviewOfControllers.html (http://www.scottpages.net/ReviewOfControllers.html) ) and pulsed output will confuse a DMM on both DC and AC settings.
Thanks both. I think I'll try a 5-pole on the DMU first. I have heard that the standard Lima wheels are not very good on pick-up so, may give these an upgrade at the same time..(I like the Bachmann 00 DMU's but they are pricey - mine was
It would be interesting to see how it compares with the 'scope trace in the web page I linked and if the design of the controller has changed since the web page was made.
Surprisingly for a
Thanks for the warning(s) Brian. It looks like a Gaugemaster unit then !
Incidentally, is the "feedback" that's being sensed by the R965 the 'back-emf' generated by the dc motor ?
Just curious as I'm an electronics novice...
Regards,
Dave
Quote from: Dave Cooper on September 11, 2019, 19:30
Thanks for the warning(s) Brian. It looks like a Gaugemaster unit then !
Incidentally, is the "feedback" that's being sensed by the R965 the 'back-emf' generated by the dc motor ?
Just curious as I'm an electronics novice...
Regards,
Dave
Yes I think it is, and I think the modern motors by design have vertualy no back-emf, hence the problem.
But I am no expert, others need to comment on this.
Brian Meldon
Have a look at the Morley Vector- I use it for several layouts, including Woody Lane, it has the option of operating from the control panel or either of the supplied handhelds. Oh, it also has a built in CDU for point operation. An excellent
Thanks Steve, I'll add that one to the short-list.
Graeme: forgot to say thanks for the excellent link - I'm still digesting the contents !
Dave
Regarding back emf, there are subtle differences between motors, but back emf is fundamental to the operation of brushed dc motors. When operating efficiently the back emf is a sizable proportion of the supply voltage. Only at the instant of starting or when stalled is back emf zero.
The things that do vary widely are the number of windings, thickness of wires, dc resistance, geometry, magnetic field strength and so on and associated with that the inductance of the windings. Along with that, the relative proportions of back emf and the voltage dropped by the resistance will change. When stalled all the voltage is dropped across the winding resistance. When the motor has no load, very little of voltage appears across the resistance and most is back emf, opposing the supply.
In general small motors in small (i.e. 009) models are probably not run very efficiently and running closer to being stalled than in their most efficient or maximum power transfer region. Small motors are high-speed low-torque machines but we want low speed and high torque. I guess there is a trade-off in gearing as the gearing saps the power through friction and manufacturing cost is also a factor.
A difficulty is in developing a controller that can give good performance across a range of motor types and sizes. The better it is optimized for one the worse it may be for another. I guess this is were DCC wins out. It would be interesting though probably uneconomic to design a DC controller that could adjust its parameters on the fly through sensing the motor response.
Quote from: GraemeD on September 13, 2019, 11:44..............It would be interesting though probably uneconomic to design a DC controller that could adjust its parameters on the fly through sensing the motor response.
I think the 'Fidelity' controllers from New Zealand that are no longer produced, did just that?
But I could be wrong.
Brian Meldon
It was one of those that was the only other controller that would give fine control of my TTe locos (powered by Rokuhan Z loco mechanisms) other than a Gaugemaster W, all the rest just wouldn't hack it. David Churchill has one and we gave it a try, if I hadn't got the W I'd have had to borrow his!
From my experience you are faced with 2 problems, and before throwing out the baby with the bath I suggest you investigate and solve each problem on its own.
The Lima pancakes are renown for their quality problems. As it starts only at high speeds it appears to have mechanical problems. To verify that use a simple transformer and check which voltage is the minimum it starts, engine in the cradle upside down with wires to the wheels. If you can borrow a 2nd multimeter measure the current, it should be around 100mA tops. If much higher there's some binding somewhere.
Before taking things apart I would reduce the spring-pressure on the brushes as this is a common problem, it's often to high.
if that doesn't help take out all gearwheels and deburr them, another Lima issue. Run a sharp knife/ scalpel along ALL edges of each wheel (that's every tooth on both sides and the centre bore)
Before putting the gearwheels back check that the wheels turn freely.
Electric pick-up wipers pressing too hard onto the wheels can prevent free running, another thing to adjust.
Check the anchor revolves freely. It might be necessary to loosen the screws on the brush holder and move that slightly so the motor runs freely. Use a pair of wires from your controller to run the motor. If you can't put an Amperemeter in line you can roughly gauge how freely it runs with the voltage setting needed for start-up.
Now put the gearwheels back, if possible one at a time, and check that everything is moving freely at each step. There should be the slightest slack only in each gear-mesh, and no teeth must touch the bottom of the gap they go into. Oil only most sparingly after completing assembly.
Yes, Lima has always been very economical with electric pick-ups, but if the engine runs smoothly along the track that is not your worry. Certainly no harm done by adding electric pick-up from all wheels. The old metallic silver wheels were nickel-plated, and if that plating is not worn away everything should be fine (Maerklin, Trix, Fleischmann all used nickel-plated wheels). Re-plating worn wheels is not difficult, you can find the instructions on the web.
There ought to be no back-emf issue with the Lima motors, so if you have such a controller it should work.
To investigate I suggest you run one of your locomotives that run well on your controller and measure the current it draws at 3 or 4 settings. Repeat with the Lima and see what the difference is. Very cheap starter pack controllers, and those with transformer in the plug, can't deliver high current, i.e. their voltage just collapses. Most Lima motors require fairly high currents, so try a 1,5A or 2A controller (borrow one, or take your Lima to a club or exhibition). That way you'll know whether you really have a compatibility issue, or whether your Lima is just a ad performer. The latter is a good idea before you buy anything: try before you buy!
Hope this helps
Waldschrat
That's my homework sorted out for a while then !
Quote from: B.Meldon on September 13, 2019, 11:52
Quote from: GraemeD on September 13, 2019, 11:44..............It would be interesting though probably uneconomic to design a DC controller that could adjust its parameters on the fly through sensing the motor response.
I think the 'Fidelity' controllers from New Zealand that are no longer produced, did just that?
But I could be wrong.
Brian Meldon
That sound interesting. I was not aware of them. Does anyone know if there is information about them online please?
Try asking on NGRM, Graeme, I think a couple of people have one and they may know.
Thanks Blair. Will do.
It should also be noted that some of the Lima diesel chassis also have another more fundamental issue in that the brass gears on the back face of the wheels are a very slightly larger diameter than the tread face of the wheels. This will cause them to short out in the electrofrog points every time the teeth of the brass gearwheel touch the point blades. This is not a problem in dead frog points.
In general these Lima chassis with this type of motor are all quite poor chassis, personally I avoid using them myself and I would recommend others do the same. Also, and again in my opinion, it is are certainly not worth spending the time building a loco around one of these chassis as it will never run very well.
Brian Meldon
Hello Brian - I have run all 3 of my Lima diesels across electrofrog points (Peco) without any shorting problems so far...just lucky I guess.
Two of them were 'free' and the other a low-cost DMU. So, if they end up in the spares bin no great shakes. I won't spend a huge amount of time /money sorting them though - they're just for fun.
Incidentally, there are two very good Youtube videos on how to upgrade the Hornby R965 controller to handle more current (suitable for those low-efficiency motors -so they say !)
Note : there are two different mod's - one for the earlier English unit (essentially a transistor upgrade). The second (Chinese made) a bridge rectifier diode upgrade. Both add higher amperage power leads and proper heat sinks to comfortably handle up to 4 amps output.
With a bit of digging I found some information on the 'Fidelity' controller.
The designer's name is John Brouwer from New Zealand (as mentioned and which helped trace him) and he wrote:
"I write this reply as a small hobby manufacturer of a controller which has
been available for over 5 years and which has been favourably reviewed
internationally. That is not a commercial but just to present the context
in which I write.
The class of controller which the CC represents is the "Voltage Feedback"
type, or perhaps more practically, a "constant voltage" type. The
controller attempts to keep the output voltage at a constant level
regardless of load (high impedance, low impedance, whatever). This it does
via the diode from the output back to the base of the output Darlington
pair. This type was described in various forms by Roger Amos in his 2
volumes about model railway electronics (UK). The Britsh EM gauge society
also publishes a circuit."
https://groups.google.com/forum/m/#!topic/rec.models.railroad/6wieV8zSxW8 (https://groups.google.com/forum/m/#!topic/rec.models.railroad/6wieV8zSxW8)
The book he refers to is this one:
https://www.amazon.co.uk/Complete-Book-Model-Railway-Electronics/dp/185260591X/ref=sr_1_1?keywords=roger+amos&qid=1568578400&sr=8-1
(https://www.amazon.co.uk/Complete-Book-Model-Railway-Electronics/dp/185260591X/ref=sr_1_1?keywords=roger+amos&qid=1568578400&sr=8-1)
It shows its age a bit, but is an excellent book.
Interseting notes about the Fidelity controller.
I was present at a test sesion of various non DCC controllers on various 009/H0e/N gauge chassis a few years ago now.
Some worked very well with the older motors, some worked very well with the newer type motors.
A couple worked ok with both.
However the one that worked best with all types of motors was the Fidelity controller.
Brian Meldon
In the synopsis of the book that Graeme refers to it mentions op. amps but not mosfets...this may just be an 'age-related' thing, or, maybe because no-one uses brushless motors on their layouts (not sure about DCC) ?
BTW, does anyone know if the Fidelity controller is still available - even if as a DIY project it would be fun to have a go at building one if the merits are as claimed.
Dave
I think you are right Dave and it is a date of publication thing in that the Roger Amos' designs date from a time when MOSFETs were not very common and no doubt expensive. There is also the matter that most model railway motors draw little current at low voltage where "conventional" transistors (BJTs) are perfectly adequate.
It is a different matter in DCC where a command station/booster has to supply power to several or many trains and accessories and in the locomotive decoders where the heat generated by a linear BJT circuit could cause problems. It makes a lot more sense then to use MOSFETs in the booster and decoders, both using PWM or similar switched outputs.
For a hand-held controller the heat generated by a linear controller can make a useful handwarmer on cold days. :D
(MOSFETs are very good at switching on and off quickly and behave like a good approximation to an ideal switch with a very low "on" resistance and so dissipate little heat.)
If anyone is interested Roger's web page is here: http://www.rogeramos.co.uk/mre.htm (http://www.rogeramos.co.uk/mre.htm)
Thanks for the link to Roger's designs Graeme - very useful (especially to DIY'ers like myself)....no 'royalties' to worry about just a designer's credit which is fair enough.
Quote from: Dave Cooper on September 16, 2019, 10:54
BTW, does anyone know if the Fidelity controller is still available - even if as a DIY project it would be fun to have a go at building one if the merits are as claimed.
Dave
As far as I know sadly no it is no longer available.
It was only ever available by ordering from New Zealand.
Brian Meldon
As it all is oh so dry I'll add a picture. With a 2nd hand buy came a coreless that self disintegrated. If you wondered how the magic inside looks, here is the detail. Enjoy!!!
And no, don't try that at home: there is no way of putting it together again. I can't even get the anchor back into the shell! :laugh:
And yes, that's one mm squares on the paper.
All the best
Waldschrat
Next picture ;D
Very interesting but I cannot see what it has to do with the thread title: Basic DC Controllers. ???
Showing what a coreless motor looks like in the flesh, the one that causes so may issues for some controllers and which we've been discussing. I've never seen one "broken down" before so was quite interested. OK not completely OT but quite relevant?
Gentlemen,
It's got EVERYTHING to do with the thread, you just need to look properly! :laugh:
Don't you see the mass of the anchor, and its diameter? What inertia?
Don't you notice the poles and the brushes?
Compare these details with the traditional motor we all know! Is it realistic to expect a 'basic DC controller' to work well with both types of motors? Especially, as 'basic' implies that such controller is unlikely to deliver smooth DC. ;D ;D ;D
Obvious, my dear Watson.
Waldschrat
That's interesting - your use of the word anchor in the context of motors
In another place someone was referring to pager-type coreless motors as "clock anchor motors" (klok anker motor). I was wondering how the idiom came about. I'm guessing it is due to the similarity in shape of the eccentric counterweight to a clock anchor escapement (which I presume is so called due to its even closer resemblance to a ship's anchor).
Anchor == armature in this context, I think?
Quote from: hughn on September 22, 2019, 21:10
Anchor == armature in this context, I think?
Yes - my mistake. I've just looked up electric motors in the German version of Wikipedia.
I got myself lost down a rabbit hole as its seems klok is both clock and bell Dutch. Coreless motors are apparently "bell armature" motors in both Dutch and German and I'd originally mistranslated the Dutch klok anker to clock anchor and not bell armature.
It's all Greek to me....
:D
In Graeme's case it was Double Dutch! ;D
Touche Blair! Well played.
I have a general and occasional fascination with technical terms in other languages. klok anker motor = bell armature motor instead of coreless motor makes sense:
Apart from the specific meaning applied to the rotor of an electric motor - armature:
(https://forum.009society.com/proxy.php?request=http%3A%2F%2Fdc1240h7n7gpb.cloudfront.net%2Fwp-content%2Fuploads%2F1_WG901_EG10.jpg&hash=3365e9e012ef4a7614e5cee2b3a17b368e28bfbe)
http://dc1240h7n7gpb.cloudfront.net/wp-content/uploads/1_WG901_EG10.jpg (http://dc1240h7n7gpb.cloudfront.net/wp-content/uploads/1_WG901_EG10.jpg)
plus bell:
(https://www.oneworldprojects.net/images/database/1268-Metal-Bell-Extra-Small-India-Fair-Trade-Noahs-Ark.jpg)
http://www.oneworldprojects.net/Manifest/Garden/Bells/index.cfm?productID=945 (http://www.oneworldprojects.net/Manifest/Garden/Bells/index.cfm?productID=945)
equals:
(https://3l4sbp4ao2771ln0f54chhvm-wpengine.netdna-ssl.com/wp-content/uploads/2018/10/Coreless-DC-Rotor.jpg)
https://www.motioncontroltips.com/what-are-coreless-dc-motors/ (https://www.motioncontroltips.com/what-are-coreless-dc-motors/)
I was hoping to find a video of the armature being wound. I suspect a cunning and very precise form of knitting. :)
Hi Waldschrat - can you say how many windings/phases does the motor you took apart have please? I can't see the commutator to count the slots. Thanks
Graeme
If anyone's interested in playing further, I took one out of an old mobile phone the other day. I think the eccentric whizzing around makes it 'tremble' when a certain phone notification is activated. (Incoming call ?).
I applied a 6v supply (4xAA cells) and it got quite hot very quickly. However, at 3v it seemed happy enough...
I intend to use it, with a suitable 'dropper' resistor to power an accessory on the layout where space is tight. It's diameter is about 4mm and length around 10-12mm...I assume from this it's probably coreless ?
I think it is almost certainly coreless. In the "early days" the only way to get your hands on a small coreless motor was in the form of "pager motors" and find a way of removing the eccentric weight.
Dear Greame, and all others,
Apologies for my German background seeping through: in German the armature of an electric motor is the anchor, and of course, I meant armature; I take it that doesn't qualify as typo? :laugh: :laugh: :laugh:
...and if you take any old pancake motor (Maerklin; Fleischmann, Lima, Trix) apart, you can see where that one came from: the armatures have 3 anchor-shaped poles. To us the 'armature' is the coil only, as in relay-armature (with or without core).
Sorry Greame, I have no intention to unwind the armature. As the wire-windings are self-supporting, i.e. not wound around anything (I'm sure they were during manufacture, but that core is not part of the finished article), I'm confident that any attempt to unwind will end in a mess.
Bear in mind that motor is the diameter of a pencil, i.e. the pictures are a massive magnification! The squares on the paper have a side-length of 1mm, not 1cm, i.e. you're looking at hair-thin (or less!) wires! It appears the metal 'can' is squashed, I can't even slide the armature back in! But you don't see that un-roundness in the pictures!
I have had a look with various (Jeweller's) magnifying glasses, including 20x, and I'm still not sure how the commutation works. And I have been unable to discern the number of poles either!
The 2 plastic pieces with wires attached must be the brush holder (broken, when the can was squashed), and the grey disk joining the copper armature to the shaft are the actual commutator, but you can't actually see individual contact pads.
I suspect the actual brushes and brush springs are lost, as I said, it came like that with an engine in a plastic bag, so I don't know how careful the previous owner was in collecting all bits. ???
Yes, Dave, I do the same with every old mobile I can get my sweaty little palms on; a cheap source of very small coreless motors, try Ericsson, the smallest I found so far. And yes, of course these are coreless motors like the one pictured. But some very new designs don't use motors anymore to vibrate. >:(
Cheers
Waldschrat
Many thanks.
My interest is in the derivation of technical terms in different languages (and different countries speaking the same language). It is very easy to think of a word being used in just one context and that might not relate to the original use, so I'm curious as to why the part of a motor that rotates is called the anchor. From an English language perspective it seems to suggest the opposite of the idea of an anchor.
Taking a different concept, in English, electromotive force and potential difference are referred to as voltage, except when dealing with high voltages where "high tension" is used. This seems to reflect the French word for voltage - Tension. Tension expresses the idea of forces between separated electric charges (as in a capacitor and is a good mental image of the energy stored), whereas a common English mental image of voltage is that of pressure (as in head of water and water/electric current flow). It makes me wonder whether the difference between the notion of "pulling" and "pushing" has any bearing on the way in which electricity is thought about.
Dear Greame,
As I said, anchor in German goes back to the shape of the pole on old-style electric motor, like those pancakes have. It is not about the function (anchoring something), but about the shape.
The German 'Spannung' correctly translates to tension, in both English and French; as does 'Strom' to current. Voltage is a creep in English as it refers to the unit (Volt) rather than to the physical effect, i.e. tension.
But why do you charge a capacitor, and not load it when you put a load of electrons on it? ;D It's not exactly the charge of the light brigade, or is it? :D
By the bye, this creep of meaning in English is common and drives us foreigners nuts, especially where words of foreign origin are involved. In German, 'Hinterland' is ONLY the area of commercial interaction of a place, e.g. town; but that's not the way it is used in English. Flammable in Latin means 'it can burn', inflammable means 'it can be ignited'; a distinction lost in English.
But we're going off-topic. :D
Cheers
Stefan
On the other hand ...
In the past we had radios with high tension (90 v plus) and low tension (6v) batteries. Those were the radios with those funny glass bottles in them.
You charge a capacitor when you put the charge in it. You also charge your glass when you pour the drink into it.
Oddly, inflammable does not mean it will not burn.
And when you boot a computer you load the bootstrap loader, the simple bit of software that loads the operating system, thereby allowing the computer to pull istelf up by its bootstraps.
Isn't English a wonderful language!
Frank
Gosh - we've come a long way from controllers to semantics...
I did Latin for just 3 years - maybe it will have some use after all !
Dave