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Offline thing fish  
#1 Posted : 21 February 2020 19:19:26(UTC)
thing fish

Turkey   
Joined: 25/01/2020(UTC)
Posts: 144
Location: istanbul
Hi there,

I'm starting out a project with reed relays and would love to hear about your experiences about

1) maximum distance of the magnet to the relay to trigger it
2) size of the magnet

Thanks inadvance ...

Cem.
Offline Purellum  
#2 Posted : 21 February 2020 22:07:38(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,470
Location: Mullerup, 4200 Slagelse
Cool

This can't just be answered in a simple way BigGrin

You can buy "normal" magnets or "rare earth magnets", also called "neodymium magnets";
the difference in strength is very big, and thus also the usable distance from magnet to reed relay.

You can also buy reed relays with different sensitivity specifications......... Cool

From Wikipedia: "One important quality of the switch is its sensitivity, the amount of magnetic field necessary to actuate it. Sensitivity is measured in units of ampere-turns (AT), corresponding to the current in a test coil multiplied by the number of turns in the test coil. Typical pull-in sensitivities for commercial devices are in the 10 to 60 AT range. The lower the AT, the more sensitive the reed switch. Smaller reed switches, which have smaller parts, are generally more sensitive to magnetic fields."

A good idea if you choose Neodymium magnets, is to cover each magnet in a layer of e.g. 1mm plastic,
so you can't connect two magnets "magnet to magnet" without the plastic between them.

They are so strong in magnetic strength; but at the same time fragile as glass, so two magnets "slamming together"
can cause tiny parts of the magnets to break of, very sharp tiny parts.......... Cool

You have to make tests with the parts you have or can get BigGrin

Per.

Cool

If you can dream it, you can do it!

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thanks 3 users liked this useful post by Purellum
Offline thing fish  
#3 Posted : 22 February 2020 01:46:18(UTC)
thing fish

Turkey   
Joined: 25/01/2020(UTC)
Posts: 144
Location: istanbul
Originally Posted by: Purellum Go to Quoted Post
You have to make tests with the parts you have or can get BigGrin


That's why I asked the question in the first place. I didn't know reed relays came with different sensitivity levels; that was very helpful. Thanks.

C.

Offline quarkhirad  
#4 Posted : 20 January 2023 22:30:50(UTC)
quarkhirad

India   
Joined: 25/05/2012(UTC)
Posts: 52
Location: surat
Hi i am going to be using a magnetic reed relay on my layout. The marklin ones are so freaking expensive and the magnets are a total rip off. Hence i was looking at buying of the shelf relays and Neodymium magnets from amazon (link given below ). As neodymium magnets are very strong, i have some doubts.

1) When i install them on the truck of the locomotive (or under the locomotive if there is not enough clearance for installing it on the wheel truck). will the magnetic field cause interference with the digital decoder and speakers in the locomotive.


2) I have a 74924 automatic grade crossing. Will the magnet cause any issues as it passes over the grade crossing

3) I have installed turnout mechanism and digital decoders for my turnouts .Will the magnet cause any issues with the turnout mechanism and digital decoders.


Basically wondering if anyone has used the magnets and found any difficulty.



https://www.amazon.ca/DIYMAG-Neo...101&sr=1-11&th=1
Offline PMPeter  
#5 Posted : 21 January 2023 00:46:11(UTC)
PMPeter

Canada   
Joined: 04/04/2013(UTC)
Posts: 1,236
Location: Port Moody, BC
Since you have revived 2 old posts to ask this question, I'm not sure which one to reply to.

Anyway, I use neodymium magnets for all of my locos and have never had an issue with the decoders or speakers within the locos. However, due to their strength I have had problems with some of the Maerklin K track switches where the magnet pulls up the point end and it shorts against the loco bottom. This mainly happens with the old design of the 3 way turnouts that still have the built in solenoid drives. Repositioning of the magnet so that the front wheels are holding it down, if possible, usually solves this problem. This was not always possible so I have now rebuilt the turnout so that the magnet cannot lift up the loose end.

With C-track I have not had any problems with the magnets.
thanks 1 user liked this useful post by PMPeter
Offline river6109  
#6 Posted : 21 January 2023 12:18:38(UTC)
river6109

Australia   
Joined: 22/01/2009(UTC)
Posts: 14,115
Location: On 1965 Märklin Boulevard just around from Roco Square
What tracks are you using ?
https://www.youtube.com/river6109
https://www.youtube.com/6109river
5 years in Destruction mode
50 years in Repairing mode
Offline quarkhirad  
#7 Posted : 22 January 2023 05:30:35(UTC)
quarkhirad

India   
Joined: 25/05/2012(UTC)
Posts: 52
Location: surat
Originally Posted by: PMPeter Go to Quoted Post
Since you have revived 2 old posts to ask this question, I'm not sure which one to reply to.

Anyway, I use neodymium magnets for all of my locos and have never had an issue with the decoders or speakers within the locos. However, due to their strength I have had problems with some of the Maerklin K track switches where the magnet pulls up the point end and it shorts against the loco bottom. This mainly happens with the old design of the 3 way turnouts that still have the built in solenoid drives. Repositioning of the magnet so that the front wheels are holding it down, if possible, usually solves this problem. This was not always possible so I have now rebuilt the turnout so that the magnet cannot lift up the loose end.

With C-track I have not had any problems with the magnets.


Well thank you and i use C track and M- Track . So i can see my c track shouldnt have any issues. Though what about M Track
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