I want to experiment with tiny LEDs for wagon lighting. As we saw in another thread, somebody suggested powering them from a battery instead of the track. Any recommendations for LEDs?
Is it the LEDs themselves you are looking for information on, or a circuit to power them using a battery?
Are you planning to solder surface mount (SMD) LEDs yourself or buy pre-wired ones?
Thanks, Graeme,
I've learned more since I started this thread. I'm homing in on the LED strips and latching reed switches sold by https://www.layouts4u.net/. The only short-term problem is that they're out of stock on the latching reed switches, which I cannot find anywhere else in the world.
Making a latching reed switch out of a plain one is physically not difficult, but finding the right balance of magnet strength and/or distance from the leaves of the switch could be challenging. As can be seen from the photos on Layouts4u, it looks as if it is just a small magnet attached by heat-shrink tube to the barrel of the reed. Often this is hidden away under a fancy plastic case that raises the price by an order of magnitude. ;)
The idea is that the small magnet in itself is not strong enough to close the contacts but when another magnet is brought close they do close and the small magnet is enough to keep them closed. Turning the big magnet around makes the fields oppose one another and the reed opens. The challenge is to have it happen consistently and reliably.
When you say wagon lighting, is it white carriage lighting or say a red tail light?
Thanks, Graeme (again!)!
By carriage lighting I mean interior, and it should be 'warm' and not 'arc-welder'.
I had already read a bit about making a simple reed switch latch, and decided I was sure I could not get it right. But I didn't realize until reading your new post that the good people at layouts4u probably do it themselves, which would be why I can't find anything similar anywhere in the internet world. I've ordered two of their kits, to sort out what's what (apparently they have latching reed switches in stock for this purpose, or are willing to do some up), and hope to buy enough of the separate materials later once I'm an old hand at installation.
Tom
That's good, they're back in stock.
Your question has sparked my curiosity. I've not tried converting a normal reed switch but I imagine it could be done if a sufficient number of reed switches and magnets could be gathered to experiment with. No luck finding information on doing it but I did find a photo of what looks like it might be a small business' go at conversion which does look very like a magnet taped to a reed -
(https://model-railroad-hobbyist.com/sites/model-railroad-hobbyist.com/files/users/joef/IMG-0302-w.jpg)
https://model-railroad-hobbyist.com/magazine/mrh2020-01/electrical-impulses (https://model-railroad-hobbyist.com/magazine/mrh2020-01/electrical-impulses)
Just in the interests of member education, can someone kindly explain what a latching reed switch is and why you'd want/need to use it (as opposed to a 'normal' switch, whatever that is) in conjunction with LED lighting?
Yours, ignorantly (but looking forward to being enlightened, by LED or otherwise),
David.
David,
Twenty-four hours ago I would have been asking the same question. But now I can explain that a reed switch is a tiny electrical switch that can be operated by a nearby magnet. They can be the 'normally on' type, which can be momentarily turned off by a nearby magnet, or 'normally off', which can be momentarily turned on by a magnet. Latching switches stay on when turned on and stay off when turned off. I gather that reed switches cannot normally be latching, but clever people can attach a small magnet in such a way (as Graeme has explained) that it works.
Now for the most 'illuminating' part: you might want them for switching coach lighting (interior or trailing light) (battery or track-powered) on and off by remote magnet. Apparently people build the switch into coach roofs if they want the magnet to be hand-held or in a bridge or something, or in the underframe for a magnet buried in the track (which I think could get mixed up with uncoupling).
The other ways to control coach lighting would seem to be switches that you actually have to touch, or perhaps operate with a mechanical device, or by DCC if you're already using track power, which would be mighty expensive for any rake of coaches. Or does anybody have other ideas?
Graeme, loose latching reed switches are still out of stock at layouts4u, but they seem to be able to sell them in their coach lighting kits.
It might be a tad complicated, but I wonder if you could arrange a reed switch together with a magnet in such a way the the magnet is restrained to slide along the side of the switch by the application of an iron "wand" outside the carriage? moving the wand in one direction would cause the magnet to cover the reed switch, turning it ON, and moving the wand in the other direction would move the magnet away from the reed, turning it OFF.
I can see that latching reeds are not to be found in RAPID, or CPC, whereas conventional ones are..
Hugh,
Might it not be simpler to have this sliding magnet make or break the circuit itself?
Tom
Latching reed switches on eBay from £22 - £36 each!
£5 from https://www.railwayscenics.com/magnetic-reed-switch-stable-form-latching-normally-open-p-3694.html (https://www.railwayscenics.com/magnetic-reed-switch-stable-form-latching-normally-open-p-3694.html)
Well spotted, Andrew!
have you seen this? https://gibitrains.pagesperso-orange.fr/en/modifications/fil-beurre/fil-beurre-04.htm
home made !
its a link I found in https://model-railroad-hobbyist.com/magazine/mrh2020-01/electrical-impulses which may also be of interest to you.
That is a fascinating find Andy! - and one I've bookmarked.
Yes, it does show that with appropriate experimentation and delving into the theory it is possible to DIY.
FWIW.
Many years ago (50) I worked on the design of an industrial combustion control system that had to remember its operating state on loss of power ready for a start up. We used latching reed relays which had a reed switch and a magnet but with two coils to switch the reed between states. It in principal it worked well BUT the reeds did not need much of a physical knock to un-latch the reed when it was in the magnet hold state. How well they perform nowadays i do not know but i would imagine with vibration from a moving model train could un-latch them. Worth checking worst case before investing in many units.
Have you considered a trying a latched hall effect device. I have used un-latched device for turntable index reference position quite succesefully.
Quote from: Phil Court on October 10, 2021, 08:27
Have you considered a trying a latched hall effect device. I have used un-latched device for turntable index reference position quite succesefully.
Good thinking Phil!
I see one on Farnell has 20 mA open collector output which would be more than enough for a tail light and perhaps enough for low current carriage lighting in small 009 coaches. There must be many or at least several other similar devices that would do the job too. It could be smaller and neater than a reed switch too.
I've used them as sensors but not as to switch 'power'. There is a trick where they are set by momentary passing of a magnet and then reset after they have been read by turning the power off and on again, for e.g. train detection.