AC help

[lawstrains]

on my analog power pack there is a AC termainal does it have a constant feed of power the hole time or does the voltage change when i  move the throttle up  🤔

[atom3624]

Which controller is it?

What does it say at / near the outlet?

A couple of photos would help?

 

Generally, the AC supply is continuous.

 

Al.

[lawstrains]

it says AC termainal

sorry cant get any pictures of it because it is installed on my layout and is hard to get a picture of it

But thanks so much for the advice 😎 😎

[LCDR]

 The AC terminals on UK analogue controllers are usually constant uncontrolled 16 volt supply and there should be a label or printing somewhere on the unit which says so.

 

AC controllers which control speed are extremely rare, so far as I know the German firm of Marklin used to use 14V AC, and before World War 2 Meccano Hornby gauge O used 20 V AC.

 

DCC uses AC of course.

[lawstrains]

thanks very much  😎 😎 😎

[2e0dtoeric]

16v AC is usually labelled uncontrolled, and is intended for operating point motors, etc, with the appropriate momentary contact switches.

[Chrissaf]

The Accessory AC outputs on most controllers are unregulated. This means that their voltage can drop as the load on them increases. The unregulated AC output and the controlled DC output share the same input power source which typically will be unregulated too**. So the net result is that both output voltages will start to drop if the total load starts to exceed the current that is capable from the input power source.

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So there is no hard and fast answer to your question......it depends.......the outputs are dynamic in nature and vary subject to loads placed upon them.

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As a general 'rule of thumb' the AC Accessory output on a DC Analogue controller should only be used for solenoid point operations. This is because only current is required at the instant of operating the point. When points are not being operated, then all the current that is available from the input power source is then available to be used by the controlled output for playing trains.

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Note** If the input power source should be a regulated one. Then that will negate some of the effects of load on both controller outputs and maintain a more consistent output. But the regulating is not infinite. Put enough load on a power source and the regulation circuits will not be able to cope and the output voltages will go down.

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The term "Controlled" is not the same as "Regulated". A controlled output term when applied to a DC Analogue train controller, just means the output that is variable to make the loco stop, go, speed up, slow down.

[Lb101]

@Chrissaf

“The unregulated AC output and the controlled DC output share the same input power source”

Hi Chrissaf. Is this the case for all controllers? I was under the impression that the latest Hornby HM2000 for example had completely isolated controlled/uncontrolled circuitry from the power input (all sorted within the ‘control box’ itself somehow) so current draw from one doesnt effect the other and therefore no voltage drop to locos. I thought it was only the one uncontrolled AC and one uncontrolled DC which share current on this unit (that’s how the sheet it comes with reads to me anyway)

That said, I’ve noticed the ‘on’ indicator light fades when I switch it all on.

if this isn’t the case I’ll be switching all my lights and point motors to separate transformers!

On the original question, @lawstrains, can you see the make and model of your controller, might help but looks like your quest has been answered?

thanks

[Chrissaf]

My reply was aimed more at the controllers that have a separate external power source, and input a single low voltage supply into the main controller unit. The HM2000 is a direct mains input controller. As it happens I am intimately familiar with the internal workings of the HM2000. The very first input component is a multi-winding transformer. A single input primary winding for the mains input and three output winding coils. One output winding for +12 volts controlled (Controller output 1), one winding for +12 volts controlled (Controller output 2) and one winding for a dual Accessory  AC and rectified DC output. All three windings have their own dedicated bridge rectifier (3 in total) to convert the AC input to three individual DC power sources (plus the raw AC sharing the Accessory DC output).

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So it is somewhat true that each output has a degree of separation and independence. However, none of the three outputs go through any voltage regulation, and they all have a share of the current flowing in the transformer primary input winding. The primary winding and the transformer in general will have a maximum power rating that it can support. So if any of the three outputs individually puts an excessive load onto the transformer primary, then it is inevitable that the other two outputs can be affected. But to put that into perspective, the loads would need to be exceptional and exceed the transformer input / output ratings.

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Note however, that each of the three output windings have their own separate PTC (Positive Temperature Coefficient) overload protection device. A PTC is a device who's resistance goes up as current passed through it increases. When the current drops then the PTC resistance also drops. This is in essence, akin to an electronic auto resetting fuse that acts dynamically to load. So this will give quite a high degree of isolation from an excessive load scenario between the three outputs because the three PTCs are dynamically managing the individual loads being placed on the transformer primary winding by the three outputs.

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This should put your mind at rest regarding the suitability of your HM2000 to meet your power requirements.

[Lb101]

Many thanks Chrissaf, now I know 😆. The cost of this controller, given its better quality and internal components compared to the Hornby standard single ‘set’ controllers (including the new model) made buying the HM2000 a no brainer for me then as I have two isolated DC tracks and so would need to have bought two of those ones. Sorry to steal the thread at the end, but it was related and gave some relevant clarity to part of the initial question I hope.

[Flashbang]

The Hornby HM2000 IMO suffers from low current on all its output feeds  - Controlled and uncontrolled.  Track (Controlled) are just 550ma maximum each (just a fraction over 1/2 Amp each) while the combined 16v AC and 12v DC outputs are even less at 300ma (approx 1/3 Amp) in total.   The accessory outputs because they are shared seriously restricts what can be connected to them.    It should be remembered that older locos can consume around the controllers maximum and possibly even more causing the overload trips to operate. 

Most other makes of 'upmarket' train controllers offer usually at least 1000ma (1.0Amp) to 1200ma (1.2Amp)  per track output. 

[LCDR]

 I have used H&M controllers for many years, Clipper & Duette in decades gone by and the HM2000 recently (well comparatively, I got mine over 10 years ago) . The philosophy behind the H&M system was that by using plugs and sockets on the sides it was possible to add a variety of modules which draw power from the main unit to control seperate circuits, operate accessories etc. and the 2000 uses a similar piriciple although limited to adding extra controllers supplied from the main transformer (I have one slave unit, but there is capacity to add two.)

 

My HM2000 has outputs on the rear for two seperate controlled 12V DC, an uncontrolled 12V DC, which is shown as shared with a 18V AC output.There are 9 pin D connectors on each side to which slave units can be plugged.

 

My old Duette has two independent controlled 12V DC outputs at the rear, 16V AC uncontrolled output through a socket on the left hand side, and an 12V DC uncontrolled output through a socket on the right hand side. The old H&M modules plugged into these side sockets using special plug in adaptors and to ensure that the correct type of module is connected to the appropriate socket they are orientated differently, DC horizontally, AC vertically.

 

All clever stuff!

 

However I now use Gaugemaster indoors and out for the layouts, although I still have a nice little Doverbeck I use for OO9.

[Lb101]

My hm2000 is newer.  They’ve done away with the slave sockets so only the two control knobs it has can be used (they changed the power to 470 mA I believe for controlled, I may be wrong on that). That said I changed where I park all my locos recently so had to reverse them all out.  I had no fewer than 5 locos running on one track at one point with no trips (all newer locos). I’ve also had at least two old locos running. Suffice to say, as I always tend to run one at a time, or two if parking one whilst moving one out, this unit does the job for me!

i think it’s tripped once in the 4 years I’ve had it, I think when a loco derailed and cause a short circuit across the rails. 

[Lb101]

I think actually it’s 450 mA for each controlled output now (the manual is in the loft somewher).  No slave connectors post 2015 probably due to above sharing reasons.. Though Hattons website say it’s 500 mA (And mention the new one doesn’t have connections to the now discontinued slaves, which were R8013 for left and R8013a for right)

[96RAF]

Off topic, but Great Eastern Models of Norwich were flogging HM2000 and slave units recently at a very decent price, along with other analogue controllers.