 Joined: 13/05/2021(UTC) Posts: 11 Location: Washington, Spokane
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New to marklin What is a Reed switch?
Thanks for all the knowledge and support on this subject. Ctrack
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Joined: 10/02/2021(UTC) Posts: 3,889 Location: Michigan, Troy
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Welcome brudon82! A reed switch is a one direction only dependent contact switch which mounts on the track and as the pickup shoe, a magnet, or a sprung metal tab on the car bottom rolls over it completes a feedback circuit to trigger an event, signal, or turnout.
These are usually connected to the digital control unit with an S-88 feedback module or equivalent. They can be used in comjunction with other contact tracks for additional events, etc. which are wheel only activated and are not direction dependent.
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 1 user liked this useful post by marklinist5999
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 Joined: 23/07/2014(UTC) Posts: 8,472 Location: ENGLAND, Didcot
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Originally Posted by: marklinist5999  Welcome brudon82! A reed switch is a one direction only dependent contact switch which mounts on the track and as the pickup shoe, a magnet, or a sprung metal tab on the car bottom rolls over it completes a feedback circuit to trigger an event, signal, or turnout.
You are talking about two totally different kinds of contacts here, the pickup shoe operated ones are NOT reed switches, but are mechanical switches operated by mechanical means. A reed switch is always operated by a magnet, and consist of a glass tube, about an inch (25mm) long (typically) and about an 1/8 inch (3.2mm) diameter. There is a wire at each end (see picture).  Image from Wikipedia, André Karwath aka Aka - Own work, CC BY-SA 2.5, https://commons.wikimedi...w/index.php?curid=124713They are usually supplied as normally open (as illustrated), but can be manufactured as normally closed, or it is possible to get them (but very rare) with changeover contacts. They are operated to the opposite state using a magnet. They may be polarity sensitive to the magnet (i.e. you may need the North and South poles to be in the correct orientation to operate the switch). Originally they were designed for use in telephone exchanges when these were first being converted to electronic exchanges from the old mechanical switches that were driven by rotary dial telephone. They were operated by a coil of wire that was slid over the reed switch rather than a permanent magnet. Marklin supply a reed switch on a plastic housing to mount on track, and magnets to fit to rolling stock or locos. These can be an alternative method to the pickup shoe method mentioned above, for detecting trains. You don't need to use Marklins reed switch, any reed switch could be used, or there are other magnet detecting methods that can be used as an alternative, but that is a different subject.
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5 users liked this useful post by kiwiAlan
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 Joined: 17/09/2006(UTC) Posts: 18,771 Location: New Zealand
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Originally Posted by: kiwiAlan Marklin supply a reed switch on a plastic housing to mount on track..... That would be the Marklin 7555. Viessmann also produce a similar reed switch - #6840. 
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1 user liked this useful post by Bigdaddynz
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 Joined: 04/12/2013(UTC) Posts: 2,261 Location: Hobart, Australia
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Originally Posted by: brudon82 New to marklin What is a Reed switch?
Thanks for all the knowledge and support on this subject. Ctrack Hi, Welcome to the forum  . Märklin make a reed switch :     and also make the small magnets to attach to the locos or rolling stock passing over the switch, e.g. :  This then closes the contacts in the reed switch, which can then signal many applications, be them “analogue” or digital. It is one option amongst many of how to signal an event on the layout. I considered the use of reed switches when constructing my current layout in the mid 1990’s but decided from my particular situation that they were not for me, but they are used by many folk. Enjoy your trains!  Regards, PJ
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1 user liked this useful post by PJMärklin
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Joined: 04/12/2013(UTC) Posts: 2,261 Location: Hobart, Australia
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Originally Posted by: marklinist5999 Welcome brudon82! A reed switch is a one direction only dependent contact switch which mounts on the track and as the pickup shoe, a magnet, or a sprung metal tab on the car bottom rolls over it completes a feedback circuit to trigger an event, signal, or turnout.
These are usually connected to the digital control unit with an S-88 feedback module or equivalent. They can be used in comjunction with other contact tracks for additional events, etc. which are wheel only activated and are not direction dependent. Hello 99, Sadly, I was somewhat disappointed that you again provided what might be regarded as a rapid but quite erroneous reply to a new member seeking help.  It can be seen from the information subsequently posted on this thread, that the reed switch by Märklin only works by way of a magnet (in our modelleisenbahn case fitted to locos or rolling stock passing over the switch). As indeed do all reed switches as noted here : https://en.wikipedia.org/wiki/Reed_switchThey are thus also not "direction-dependent". New members should be able to reasonably expect (and rely on) truthful, accurate answers to their questions on this forum.  Unfounded answers just confuse new members and then require correction by other members, making it all rather messy  , as has been noted with concern on this forum previously. My comments are posted hopefully with persuasive goodwill, no malice and in the altruistic hope that we may see useful information posted to new members Regards, PJ 
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4 users liked this useful post by PJMärklin
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Joined: 13/05/2021(UTC) Posts: 11 Location: Washington, Spokane
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Thank you so much for all the answers, the knowledge on this forum is outstanding.
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1 user liked this useful post by brudon82
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Joined: 10/02/2021(UTC) Posts: 3,889 Location: Michigan, Troy
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Your welcome! Now you know every option!
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