Transformer

cardmodeller said:

DCC for Hornby Dublo 3-rail? Wouldn't that be like running a Morris Minor on the latest High-Octane fuel and expecting a better ride?
I could be wrong but I can't help thinking that it would be a waste of money...

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Terry, this depends entirely on your priorities. Using the Morris Minor analogy, it's not a better ride; the lousy suspension, steering and zero sound insulation, awful seats and pedal placement, will be the same as ever. But what you would gain from equivalent improvement to the engine, is a car that starts everytime and keeps going come what may with a service only required every five years.

The big problem with DC is that low speed control is compromised by the necessary low voltage on the rails. DCC kicks that problem into touch, with HO decoders you can run the track at as much as 22V if you buy the right system and decoders, and the poor contact problem ceases to exist. (If belt and braces are required, you can also fit a capacitor based unit ('stay alive') to ensure continuing power supply to the decoder and motor, which can read the track signal while out of electrical contact.)

This is definitely worthwhile for the ringfield motor H-D product. These will crawl dead slow under the iron control of DCC, for very realistic starts and stops. It will help the other motors in the range for reliable running, but typically this won't be equal to the ringfield at dead slow performance.

Tim Waters said:

Thank you for this advice, so you would not recommend the Gaugemaster Q for Dublo 3 rail?

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Hi Tim
I have no idea how the Gaugemaster or others work with Dublo locomotives but I can tell you the H&H controllers are perfect for them as it’s what they were basically built for. The H&M Clippers and Duette also control all of the latest locomotives very well so don’t be told otherwise, I have some of the latest RTR models by Locomotion, Rails of Sheffield, Oxford rails, Hattons, Bachman and Hornby all work perfectly on the high resistance setting and on full Wave setting. The advantage that H&M had over a lot of controllers in the past is their simplicity to operate as the control knob has a centre off position turning clockwise for forward and anti clockwise for reverse, no reverse switch to worry about that a lot of other brands had. There are lots of horror stories about the H&M products being unsafe, if they are the old Autotransformer Powermaster types of the 1950s yes they were lacking in safety which is where I believe this Stigma came from, when I restore these I correct the unsafe parts of its design (Wiring) to overcome this. The latest design of Clippers and Duette,s are great no problems other than ware and tear to the mains lead which may need replacing these do have a Asbestos mat that the reostat is wrapped around but it’s inside and there is no problem with it if you don’t open it up, I have never seen a mat fall apart they have always been solid and in one piece sometimes warped a little which was the reason for the speed control missing here and there but it can be realigned easily.
Perhaps get in touch with a Hornby Dublo club they could tell you what is the best modern Controller to suit, if that’s the way you wish to go. Sorry for any spelling mistakes this spell check has been killing me I’ve given up on it !

Tim Waters said:

That’s really helpful, shall follow your advice & many thanks.
Could you explain what the ‘wave’ & ‘resistance’ do please?

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Hi Tim
The Two switches are use to give the best operating control for motors of different types some need finer control of voltage some don’t, depending on the model you are running HORNBY Dublo / Wrenn both can need the controller moved towards a fast setting to move them along from a standing position with a heavy current draw but then the controller is backed off to obtain a running speed with a much reduced current draw, modern motors will move off with just a touch of the knob. The older Motors are not like the modern ones and the weight of the Di-cast locos are heaver so fine shunting movements are out of the question they can move-crawl slow but I wouldn’t recommend it Long term, ( the HALF WAVE switch can help with crawl ) remember if the motor buzzes at low speed increase the voltage buzzing or loud hum on any motor means eventually a burn out. (overheating)
Without getting into the nitty grittys of exactly how the switches operate the circuitry, the High and Low resistance switch gives you a choice of scale, the scale represents (voltage) on the controller knob, imagine a scale of speed of say 1 to 12 in forward and reverse using the HIGH SETTING, with the rotation of the knob the engine starts off dead slow at 1 to maximum speed at 12 (volts) now when the switch is set to the LOW SETTING the scale (voltage) changes and starts at 6 (volts) to a maximum of 12 (volts) so the motor gets a higher voltage to start for the older motors but naturally is no good for modern locomotives they would probably fly off the rails they need to operate more to the lower voltage requirements of what the HIGH Setting can give.
The HALF & FULL WAVE setting gives you different choices of power from the VOLTAGE RECTIFIER that is part of the circuitry. On the FULL WAVE setting the power goes through the entire Rectifier and is converted from AC to FULL DC so a smooth 0 to 12 volts is supplied to the loco like the power that comes out of a battery but when the switch is in the HALF WAVE position the power only goes through half of the VOLTAGE RECTIFIER so the power to your loco it is not smooth it Pulsates and this can be used for shunting locomotives with older motors, the 12 volt power pulses the armature around it can give a clogging sound to the motor as it rotates which can be heard on some models. I use it to shunt on some locos then change back to FULL WAVE to move off I just don’t like a DC motor running on half wave, some motors can overheat on HALF WAVE some don’t you will soon find by experience which setting is best I have mine basically set on HIGH RESISTANCE & FULL WAVE all the time. Just remember the condition of your locomotive and it’s motor has a lot to play in all this especially the older motors and their old magnets as they deteriorate the motors current increases and their top speed decreases.
Hope this helps.

If going the old H&M controller route, definitely make the purchase conditional on a PAT pass from a qualified electrician, and also have it tested for sustained rated DC power output.

As mentioned above the double insulation has to be fully operating for safety, and of the internal components, the rectifiers do eventually start to degrade, reducing current output.

I have both a Clipper and a Duette, the latter my standard DC resistance controller test for all new locos ahead of decoder fitting. However, the Duette is fitted with the high resistance rheostat mats which were an option back in the day, which is fine for modern can motors, not so useful with a H-D ringfield. For these I use the Clipper, which supplies more current and has the standard mat suited to 1960s and earlier motors: it's rectifier was replaced long ago by a more modern unit, as it was very intensively used in my youth, as often for electroplating and electrolysis as running the trains, until I got to do physics A level, and had easy access to more robust gear.

Rapido are being cautious there. The particularly problematic output from Hammant & Morgan Duettes or Clippers is the 'half wave' selector which will give a coreless motor a good rattling at 50Hz, which is not best for their longevity.

Otherwise these controllers do what all 'resistance' type DC controllers do, and puts out rectified DC which is a 100Hz non-sinusoidal waveform. This isn't ideal for coreless motors, but a lot better than the 'halfwave' which is '10ms on, 10ms' off, which 'jerks' the low mass armature of a coreless motor around.

I have these very controllers, and the Duette is most useful for test running current OO models before decoder fitting, so that any mechanism shortcomings are detected and corrected. But there are two factors which make this safe. Firstly the resistance mats installed were the optional 'high' type, which significantly limits current; and then something I did long ago when iron core can motors - such as Mashima - became standard, was disconnect the 'half wave' output as redundant. I have test run all my RTR OO purchases these last 23 years on the Duette, and that includes coreless motored product from brands including Rapido, and had no consequent trouble: so they are not the 'spawn of satan', but do need to be used with thought. (The Clipper is in original condition and used when a 1960s or earlier OO model needs a good wallop to get it going, the old heavyweight iron core motors need the current this unit can deliver.)

Practically every other DC resistance type controller will be 'as bad' as the H&M product, though few if any will offer 'halfwave': but most won't have survived in usable condition! The H&M product was of pretty much 'bombproof' overall construction, and thus many still work...