Problems with Maglights

[BenjiBoogle]

I only currently own 1 'Maglight' coach but have recently been experiencing troubles like this one.

What happened?

Well, when running a loco (no type in particular) when passing it or pulling it past another engine, the lights either turn on or off.

Resolution?

I'm not entirely sure what the cause for this mishap is but it may be due to the material of a certain component in the object. If anyone knows an actual resolution, please comment. Thank you.

[Potterton]

I have had the same experience with the lighting system I use. (Not actually Maglights itself, but basically the same.)

What is happening is that the reed switch in your Maglight is being activated by the influence of the magnet in the motor of the engine your coach is passing. In my case, the reed switches are non-latching, (due to be changed), so the lights come on as the train passes the engine and go off again when "out of range." Maglights employ a latching reed switch so as your coach passes the engine the lights will switch either on or off, depending on whether they are on or off in the first place.

The only resolution I know of is not to run the Maglight lit coach too close to another engine.

[96RAF]

I use reed switches for loco detection and if I watch the sensor monitor it can flash several times as a loco passes, once for the magnet, once for the motor and again for the tender mounted speaker. In my case it doesn’t matter as the software sees and ignores the flicker. Not so in your maglight case which I suspect is a tad annoying.

Edit - JJ had a similar problem some time ago and there was much discussion about it on here.

[JJ73]

Yes JJ here - I have 2 of these "Maglight Carriages", a dark green 4 wheeled carriage & a dark red 6 wheeled carriage!!! Where 1 night, 1 of the carriages had turn it self on - here is a link to that thread what Raf was talking about :- A ghostly experience!!! :: Hornby Hobbies

Also I made a quick vid about it :-

Mostly folk were talking about "magnetic fields", specially what Rana had to reply - read it - it is interesting & might help to answer your question!!! 😉🚂

[BenjiBoogle]

Thanks everyone for your replies! I do appreciate and support your ideas. The coach hasn't been used in a while, actually, but I do intend to run it soon.

[What About The Bee]

Has anyone attempted to shield the reed switch from stray magnetic fields?

I've used MuMetal in the past to do so. The effectiveness of the shield has much to do with field strength and orientation, but given the low field strengths generated here, it may be possible.

MuMetal is available in sheet, foil and tape form. Shield the reed switch in a well of MuMetal. Provide a MuMetal surface inside the locomotive shell for the motor of the offending locomotives.

Just a thought.

Bee

[Bulleidboy]

It must be a fairly powerful magnetic field? I am not defending the system, but I have a rake of Maglight fitted coaches, and they regularly pass other loco's (DCC Fitted/Ready - so not too ancient), and the lights never go off or on. When JJ first raised this, I found that by drawing the Maglight magnet along the side the coach would not operate the lights, and the magnet had to be very close to the carriage roof for the lights to operate. I have a magnet, probably stronger than the Maglight version, that is mounted in the top of a tunnel portal, and this operates the Maglights as the train leaves the fiddle yard and turns them off when the train returns. As was stated in the previous thread some old loco's and operating equipment had very strong magnets within.

[atom3624]

Can't believe this thread started nearly a year ago!!

Time does fly indeed.

Interesting and predictable - magnetic fields would need to be pretty strong as mentioned to affect the lighting, so curious indeed.

Al.

[JJ73]

Talk about talking time to answer back - better later than never I suppose!!! 🤔🚂

[What About The Bee]

I'm hopeful that you might try the MuMetal testing JJ. You have the ideal offending locomotive and you are armed with a compass to test the shield you make.

Bee

[JJ73]

The MuMetal Testing??? I'm not quite too sure what you mean by that Bee??? 🤔🚂

[JJ73]

Did you mean this, by any chance - The MuMetal Testing???...

Is this the sheet form you were talking about??? if so - then it didn't really work - the magnetic field still went through it!!! 😐🚂

[What About The Bee]

Hi JJ 👋

MuMetal is a special material which provides a magnetic shield.

It is widely available in many forms: sheet, foil, tape, etc.

I've used this in the past to shield components from stray magnetic fields. I think the Maglights are an ideal candidate for this.

Why? (1) the reed switch is small and easily shielded. (2) the likely magnetic fields are relatively small. MuMetal does not function well in strong fields. (3) the tape can easily be applied inside loco shells.

Now if I recall properly, JJ, you have a unique test bed. Not only do you use the maglights, but you have a known stray magnetic field. Further, you have demonstrated that the field is still present for the compass test.

Now, it is up to you. No one is demanding anything. But in the interests of science, you are an ideal candidate and, at the end, you will likely solve your maglight issue, for good!

Bee

[Topcat2018]

If the stray magnetic field is strong enough to activate the reed switch, won't it be strong enough to saturate the mumetal shield? Mumetal saturates at about 0.7 T. I don't know what field strength it takes to activate the Maglight.

[Brew Man]

Plus if you don't know where the offending magnetic field(s) are coming from you'd have to shield everything that may be suspect, (except of course the vehicles containing the Maglights).

[What About The Bee]

There are two approaches to shielding from the magnetic field.

1) you can shield the source.

2) you can shield the sink

How to shield the (sink) reed switch? Place it in a MuMetal well. Magnetic fields have direction and lines. If those do not align with the well, then they cannot trigger the reed switch.

How to trigger the reed switch then? Place your desired magnet at the mouth of the well.

Nothing stopping you from using a compass to determine which elements are generating fields (source) and shielding them as well. Simply a less cost effective method however. It might be worth it for an old Loco such as JJ demonstrated in his video.

Bee

[atom3624]

If the magnetic field is as strong as is implied, wouldn't a compass be able to assist in it's location?

Al.

[What About The Bee]

Absolutely Alan. JJ has tested with a compass and indeed, he can see it

[Topcat2018]

@ What About The Bee

What exactly do you mean by a "well" and how is the reed switch positioned within it?

[What About The Bee]

Hi Topcat 👋.

The easiest way to think of it as an old fashioned water well. In that, we have a circular tube of stone, leading down to the water. A bucket is lowered down and water is scooped up.

Analogously:

Place the reed switch on the surface of the water and make the circular tube of MuMetal, extending up. The reed switch is then within the circular tube.

Any time I want to switch the Maglight, I place my bucket (magnet) at the mouth of the well, exposing the reed switch to the magnetic field.

Bee

[Topcat2018]

@ What About The Bee

Thanks, I understand that, but to repeat my earlier question, what if an extraneous magnetic screen is strong enough to saturate the mumetal?

[What About The Bee]

Hi Topcat

I understand your objection. No magnetic screen is perfect.

Conversely, what if the magnetic field isn't strong enough to saturate the MuMetal? Well then, the issue is resolved.

To my knowledge, we do not have any numerical values. Not one person has stated the magnetic field strength at the reed switch, using a calibrated, traceable instrument. Nor have I seen any manufacturer state the field required, should an Enthusiast wish to generate a magnetic field electrically. Its all just talk, no engineering.

I've no particular skin in this. I do not have, nor will I ever have, the maglight system. Lights in coaches? What will they think of next? Flying machines? 😉

But the constant complaints that the system turns on/off randomly got me to thinking about stray magnetic fields and what I've done about them in the past. And that solution, under those sets of circumstances, was MuMetal shielding.

Is MuMetal perfect, under all fields? No. Nothing is. Is it a possible solution for the tiny fields generated by a passing 12 vdc motor present in toy trains? Yes, it is possible.

It might work, might not. Its a potential venue for exploration. A solution that will clearly work better than what is available now, to wit: nothing.

Bee