New to electrics - point motors?

[ash39]

Hi,

 

Just wired my first point motor last night and tested it, works perfectly.

 

However, I have 5 to do and I'm not sure what to do with the black wires. The Hornby diagram seems to indicate that you join them, and then send one common wire back to the power unit (mine is a Hornby HM2000). I'm not sure how you join the wires, I've been using terminal blocks for the rest of the wiring but obviously that won't work for this.

 

Also, I've read somewhere that you need a seperate transformer to stop your motors drawing current continuously and burning out. Is this true? As I also read that these are not suitable for use with Hornby passing contact switches, but this is what I've bought now.

 

Thanks

Ash

[kevinlms]

Many of your questions will be answered here.

 

http://www.brian-lambert.co.uk/Electrical.htm#Point%20Motor%20Wiring.

 

 

Definately include a CDU on your layout as it will prevent your point motors from burning out.

 

Kevin Martin

[BR60103]

Ash:

I don't know why you would need a separate transformer to stop them drawing power continuously.

You need switches with momentary contacts -- push buttons, passing contacts (like Hornby levers) or stud and probe (touch a wire to a contact).

The black wire solution is usually taking 2 black wires from the motor and twisting them together with the long black wire to the power supply. Or join the terminals on the motor and add the long wire to one of them.

[Gwiwer]

A CDU is advisory and usually prevents any risk of motor burnout since it regulates the momentary current passed to the motor to throw a point. Without a CDU the amount of current may be much more than is required and has potential to burn out a point motor though there is nothing to say that this is inevitable.

 

I have over 50 powered points. The motors are a mix of Peco surface, subsurface and subsurface long pin types. The control is via Hornby levers simply because I like the "real signalbox feel" of throwing the levers. The wiring colours of course differ between brands! I have adopted the Peco wiring colours as standard meaning for the subsurface motors there are two terminals to which the green power feed must be connected. I found the Peco instructions less than helpful in advising that to be the case and further that separate feeds are not required since the power bus goes to one and a short spur from that connects to the other terminal.

 

You need a suitable 12 volt DC output off a transformer (assuming you are using 12-volt DC point motors) but it does not have to be a different transformer. The train controller is normally quite adequate and many have 12vDC uncontrolled output terminals on the back which you can use. Where you can come unstuck is wiring points and lighting off the same output. Throwing points will then cause your lights to flicker as a pulse of power is sent to the point motor; repeated flickering of little lights is a sure-fire way to reduce their service life dramatically. Wire lighting from a separate controller or output to your points but again it doesn't have to have its own transformer even though that might be good practice.

 

My controller has an inbuilt CDU. Before I had that controller the points were worked without a CDU without a problem. I currently have a controller issue meaning the CDU is by-passed and the points continue to work. There is a much louder buzz as the surface ones throw however and there is a tendency to get a double-throw (over and back in the same burst of power) due to the amount of current being sent. The surface motors also feel noticeably warmer without the CDU after having been used a couple of times in quick succession.

[ash39]

My problem is I've just spent quite a lot on Hornby motors, housings and passing contact levers, only to now find that the passing contact switches aren't ideal for use with a CDU due to they way they are designed, but you're meant to use a CDU to stop your motors burning out.

 

How are Hornby allowed to sell these products if they aren't fit for use?

 

So basically, I either replace my 5 Hornby switches or face changing my motors every time they burn out? Surely there's another option. I still haven't worked out how to join wires either, could not find anything on the above link.

[DaveF]

I've been using Hornby passing contact switches (i.e. the black lever ones) with a CDU for my point motors for many years and have never had any problems.

 

As far as the black wires are concerned just connect them all together, using additional lengths of wire as needed, and connect them to the transformer output. I just twist the wires together and when all is working I solder them together.

 

A CDU doesn't prevent point motors burning out, it just gives a large single burst of current which helps overcome any stiffness in the point motor and point. If you use a passing contact switch electricity can only flow as you actually throw the switch, the rest of the time no current flows, so point motors cannot burn out.

 

You are only likely to burn out a modern point motor of the Hornby/Peco type if you leave the power to it switched on for more than a few seconds. Usually the motor (actually a solenoid) will buzz loudly if this happens, before anything is damaged. Again, having used point motors of this type for over 40 years I've never burnt one out.

 

David

[ash39]

When I tested the one I wired up, it buzzed loudly every time it switched. I assumed that was normal?

 

Finding it all confusing, I don't mind buying a CDU as they are only about £8 but I don't want it to make it difficult to use. According to the link posted by kevinlms, you have to hold the switch halfway for a couple of seconds to allow it to discharge, which is why it's not recommended.

 

I think I need to stress that I am an absolute beginner, I've never used a soldering iron nor do I own one. Is there no way to join them with electrical tape or can't you shove 5 black wires into a terminal block and then have one single wire coming out of the other side? I realise that won't be possible because otherwise it'd be the easy standard option, but as a newbie I don't understand why as the contacts would be touching and surely that's the only requisite?

[DaveF]

When I tested the one I wired up, it buzzed loudly every time it switched. I assumed that was normal?

 

Finding it all confusing, I don't mind buying a CDU as they are only about £8 but I don't want it to make it difficult to use. According to the link posted by kevinlms, you have to hold the switch halfway for a couple of seconds to allow it to discharge, which is why it's not recommended.

 

I think I need to stress that I am an absolute beginner, I've never used a soldering iron nor do I own one. Is there no way to join them with electrical tape or can't you shove 5 black wires into a terminal block and then have one single wire coming out of the other side? I realise that won't be possible because otherwise it'd be the easy standard option, but as a newbie I don't understand why as the contacts would be touching and surely that's the only requisite?

 

There's no reason why you shouldn't use terminal blocks with as many wires as they can hold and one coming out the other side. Or just twist the bare ends of wires together, you can them tape them but it will not be as good a joint as a terminal block or soldering if you intend to use it for several years or if the layout is portable, as if you catch the wires they may disconnect. Just twisted wires is not good practice but I have done it from time to time, usually when I have forgotten to solder them and have not had any real problems..

 

I tend to do as kevin lms says in pausing moving the lever over, it's actually to charge up the capacitor in the CDU. I don't find it a problem to do.

 

The motor will buzz as it actually throws the point, you only need to worry of it keeps buzzing after you have thrown the switch and the point has changed.

 

David

[Grovenor]

How are Hornby allowed to sell these products if they aren't fit for use?

To be fair to Hornby, they do not sell a CDU and their points and levers are designed for use with a 16V AC supply and are perfectly OK used in that way.

If you get a CDU then you are using the Hornby items in a way other than that designed and will have to cope with the resulting issues as has been described.

Regards

Keith

[Brian]

Hi

Firstly, regardless of what has been stated, a CDU will help prevent coil burn out as it reduces the current flowing to a coil to a few milliamp all the while the operating switch has its contacts closed after the initial capacitor discharge! The capacitors cannot recharge until the lever / switches contact open.

 

Without a CDU and allowing the operating switches contact to remain closed for more than a few seconds will cause coil failure due to them burning out.

 

The Hornby black point lever switch (R044) does exactly what it says on the tin.

It was never designed to work with anything other than a basic power supply of typically 16 volts ac and certainly never with a CDU.

 

However, if you want to use a CDU and also use R044 lever then all that is necessary to do is to hold the R044 lever at its top centre position for a second or two, thereby allowing the CDU to recharge fully again after it was initially discharged into the coil of the motor when the lever was first moved from the stop position.

Then as the R044 lever reaches towards the far end of its travel the CDU is connected and discharges into the correct coil thereby moving the point over. eventually the lever reaches the stop position where the internal contact is broken.

 

The internal of a R044 lever switch can be seen on my web site. As too are shown the basic wiring using R044, a sprung to centre off toggle switch, momentary push buttons and Stud & Probe.

http://www.brian-lambert.co.uk/Electrical.htm#Point%20Motor%20Wiring.

[Ron Solly]

Using the Peco passing contacts are ideal with a CDU as they are designed to give only one pulse near the end of the arc

 

 

due to the pivot arrangement, it gives a pulse & then the circuit is broken and cannot be made again until it comes back again. ( I pulled one apart to se how it worked then glued it back together to use)

[ash39]

What does the Hornby hm2000 unit put out, surely it'd male sense for it to be 16v ac if thats what the accessories take?

[Ron Solly]

What does the Hornby hm2000 unit put out, surely it'd male sense for it to be 16v ac if thats what the accessories take?

 

Reading the Hornby website

http://www.Hornby.com/shop/power-and-control/r8012-hm2000-power-controller/

 

yes, it does provide Outputs include non-variable AC and DC power for point motors and other powered accessories

[ash39]

I'm confused then, as grovenor/keith has said above, if Hornby motors are used as designed - with a 16v AC supply, then there should be no need for a CDU as Hornby do not sell one.

So if I use it with the HM2000, where's the problem?

 

Sorry, told you I was a beginner!

[Ron Solly]

Hornby point motors work with either AC from such a supply as the HM2000 via passing contact/pushbuttons or DC such as from the output of a CDU also via passing contact/push buttons.

.

With a CDU / DC , one does not get a buzzing sound and again with a good CDU, once the power has been used on a point motor, the chance of burning a coil out is diminished almost to the point of being impossible to do.

 

Hornby passing contacts switches work the best from a decent AC supply of around 2 amps if not using a CDU & not prepared to hold the switch in the centre for a second to allow re-charge.

 

Using the AC only is the cheapestmethod but not the best IMO especially when one wants to operate a few points at the same time via diode matrix ( as decribed in http://brian-lambert.co.uk/Electrical-2.htm#Diode Matrix )

[BR60103]

Certain things were not intended to be used together. Hornby point levers and CDUs are some.

The Hornby point lever is a reasonable precaution against motor burn out. There is a possibility of the contacts inside getting stuck or welded. There is a way to wire it up with 2 CDUs, one for straight, one for curved.

I don't know the Hornby point motor; I have used a lot of Peco. They can be wired using pliers to crimp the contacts around the wire.

A CDU is nice for advanced controls where you change a bunch of points at the same time.

[Gwiwer]

Certain things were not intended to be used together. Hornby point levers and CDUs are some.

 

As I use this combination perfectly successfully - and the operation is smoother with a CDU than without - may I ask your basis for holding this opinion please?

[meil]

_{As grovenor says Hornby didn't intend these to be used with a CDU but I don't see why they shouldn't work providing the "passing contact" stays contacted sufficiently to discharge the CDU.}

 

_{However at £9 a pop these are extremely expensive - I certainly wouldn't buy them. You can get (ON)-OFF-(ON) switches for about £1 , which with a CDU can provide a reliable point switching method.}

[Ron Solly]

Hattons sell Hornby R044 at £7 while the Peco version PL-26 sell at £4.50 which I think are far superior.

[jcm@gwr]

Now, I'm no expert, but I also think I'm beyond a beginner.

I have fitted a few CDU's and I'm a little confused about

this idea of 'holding the switch to allow it recharge'.

On the units I have fitted there are 2 pairs of screw

connectors, 1 pair marked 16v input and 1 pair marked

output. Therefore, as I understand it, once the power is

on, the only time it isn't charging is when you are 'firing'

the point motors.

The different switch systems are irrelevant so long as

they only pass power momentarily, ie stud & contact,

pushbutton, passing contact. The only way that you can

stop the charging is by keeping the switch contact 'on' to

the point motor. Which is a waste of time as the CDU has

discharged.

I am, of course, open to correction if I have misunderstood

how a CDU works.

Jeff

[Gwiwer]

Hornby levers, Morley CDU, Peco motors. No "holding" of levers required. Just a steady "pull" as you would with a real lever in a 12" : 1' scale frame. If you flick the lever you don't get a throw - if you pause it mid-arc you get a long loud buzz while the point flicks between normal and reverse.

[smokebox]

@Jeff

 

It's not that you have misunderstood how a CDU works. The problem is the Hornby passing contact switches which discharge the CDU when you start to move the lever - there is no mechanism to prevent it from energising the point motor in the direction it is already switched to.

 

Peco passing contact switches have a clever mechanism inside which prevents the CDU from discharging before the lever reaches the position where it will operate the point in the desired direction.

[Ron Solly]

The output of the CDU is open circuit when holding the Hornby passing contact switch, in the middle for about 1 second,& this open circuit allows the CDU to recharge - the same as it does once the passing contacts are no longer made at the end of the action.

As I indicated earlier, Hornby passing contacts are not ideal, they give two pulses in each movement of the lever. the first pulse just gives the solenoid another kick in the same direction & it is the second pulse which causes the coil to reverse the motion and unles you have a fast charging CDU, the second pulse maybe weak & thus not fullyioperate the mechanism. The Peco passing contact only gives one pulse so the full CDU output is available at the end of the movement of the lever.

My CDU circuits recharge so fast even with Peco switches, they always operate the motor no matter has fast I am on the switch movement..

[Ron Solly]

@Jeff

 

It's not that you have misunderstood how a CDU works. The problem is the Hornby passing contact switches which discharge the CDU when you start to move the lever - there is no mechanism to prevent it from energising the point motor in the direction it is already switched to.

 

Peco passing contact switches have a clever mechanism inside which prevents the CDU from discharging before the lever reaches the position where it will operate the point in the desired direction.

 

For sure- as my photos in Post #11 indicate. If in doubt pull one of each,. Pec o & Hornby apart to see the differences.

[jcm@gwr]

Ok, now I understand, I didn't realise there was a 'double' action

on the Hornby switch, [i haven't used them for years] and all the

layouts I have been involved with have either used Peco, push

button or stud & contact.

That is why I have never come across this problem before.

Cheers, Jeff