TEAMYAKIMA Posted January 16, 2022 Share Posted January 16, 2022 Hello Someone has suggested to me that you can get north and south pole reed switches. Let me explain I have various features which are triggered by locos fitted with magnets under the chassis. One track is bi-directional and ideally I would like certain features triggered by clockwise trains and others by anti-clockwise ones. If there are south and north pole reed switches, I could fit locos going in one direction with north pole magnets and locos in the other direction with south pole ones. I do realise that any magnet is either south pole or north pole depending on how its mounted and so please forgive the rather clumsy way I've phrased the question. If the answer is "no", is there any other way to achieve my aims? Link to post Share on other sites More sharing options...
cliff park Posted January 16, 2022 Share Posted January 16, 2022 If you position a permanent magnet parallel to the reed but just far enough away not to operate it then only magnets the right way round, reinforcing the weak one, will operate it. So with two reeds you could achieve what you want. The two reeds could be side by side,, with the biassing magnets placed one each side. Link to post Share on other sites More sharing options...
Golden Eagle Posted January 16, 2022 Share Posted January 16, 2022 Reed switches are not pole-specific, however Hall-effect sensors are (and come in both “south-sensing” and (less commonly) “north-sensing” versions). Depending on how good you are with electronics, you could try those, or (possibly easier) place a pair of Reed switches separated by a short distance and observe in which order they operate (which would also have the advantage that you’re not committed to running the same loco in the same direction every time. Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted January 16, 2022 RMweb Premium Share Posted January 16, 2022 (edited) 18 minutes ago, cliff park said: If you position a permanent magnet parallel to the reed but just far enough away not to operate it then only magnets the right way round, reinforcing the weak one, will operate it. So with two reeds you could achieve what you want. The two reeds could be side by side,, with the biassing magnets placed one each side. Isn't there a chance they would stick on? Two reeds in quick succession sounds the best idea to me Edited January 16, 2022 by melmerby Link to post Share on other sites More sharing options...
TEAMYAKIMA Posted January 16, 2022 Author Share Posted January 16, 2022 25 minutes ago, Golden Eagle said: Reed switches are not pole-specific, however Hall-effect sensors are (and come in both “south-sensing” and (less commonly) “north-sensing” versions). Depending on how good you are with electronics, you could try those, or (possibly easier) place a pair of Reed switches separated by a short distance and observe in which order they operate (which would also have the advantage that you’re not committed to running the same loco in the same direction every time. Sorry to be thick, but I don't understand the answer. Link to post Share on other sites More sharing options...
Golden Eagle Posted January 17, 2022 Share Posted January 17, 2022 6 hours ago, TEAMYAKIMA said: Sorry to be thick, but I don't understand the answer. Sorry! There are two types of magnetic switch (that I know of!). One is the Reed switch. As you know, this simply closes a mechanical connection in the presence of a magnetic field. It responds best to a parallel magnetic field and cannot distinguish between north and south poles of a magnet, so you can’t use one Reed switch to tell you which way a train is running. With a small number of extra components you could set up two Reed switches and trigger your effects depending on whether switch A closes before Switch B (travel is in one direction) or Switch B closes before Switch A (travel is in the other direction). The other type of magnetic switch is a “Hall-effect sensor”. These usually respond to the presence of a “south pole”, but you can get sensors which activate in the presence of a north pole. That would allow you to set up the locomotives as you describe, with a magnet oriented according to the direction of travel. Another way which might work (if you use analogue controls without an HF track cleaner) would be to measure the voltage across the rails. Positive is one direction, negative the other. A single Reed switch then triggers the relevant effect. Again, this comes down to how confident you feel about designing and building electronic circuits. Link to post Share on other sites More sharing options...
RMweb Gold PaulRhB Posted January 17, 2022 RMweb Gold Share Posted January 17, 2022 (edited) 8 hours ago, TEAMYAKIMA said: Hello Someone has suggested to me that you can get north and south pole reed switches. Let me explain I have various features which are triggered by locos fitted with magnets under the chassis. One track is bi-directional and ideally I would like certain features triggered by clockwise trains and others by anti-clockwise ones. If there are south and north pole reed switches, I could fit locos going in one direction with north pole magnets and locos in the other direction with south pole ones. I do realise that any magnet is either south pole or north pole depending on how its mounted and so please forgive the rather clumsy way I've phrased the question. If the answer is "no", is there any other way to achieve my aims? Why not just follow what LGB has done for years in reverse. They have two sensors in the loco, one left and one right for different sounds, and magnet in the track that can be orientated as required to switch them at certain times. Instead mount a small neodymium magnet on the right side of the loco so it only activates a reed on the right side of direction of travel. The advantage of a neodymium magnet is the very small field so it won’t activate a reed on the other side for the alternate direction of travel. Edited January 17, 2022 by PaulRhB 3 Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted January 17, 2022 RMweb Premium Share Posted January 17, 2022 Put the reed switch to one side of the track, say the left. Mount the magnet on the loco as far to the left as possible, that way if the loco is turned around, the magnet will be on the left still, but the track magnet will be on the right -even better if double track, then on the left depending on direction of travel. Testing should give you an indication on how much leeway you have and the magnet strength. What won't work, is if you just change the direction of the loco on single track, because it will still activate the reed switches. Link to post Share on other sites More sharing options...
Nearholmer Posted January 17, 2022 Share Posted January 17, 2022 https://patents.google.com/patent/US3599132A/en Looking at the date of this, it came just as Hall effect devices were becoming cheap and freely available, so whether it made it to market, or remained on the market, I don’t know. Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted January 17, 2022 RMweb Premium Share Posted January 17, 2022 (edited) 14 hours ago, cliff park said: If you position a permanent magnet parallel to the reed but just far enough away not to operate it then only magnets the right way round, reinforcing the weak one, will operate it. So with two reeds you could achieve what you want. The two reeds could be side by side,, with the biassing magnets placed one each side. 14 hours ago, melmerby said: Isn't there a chance they would stick on? According to some reading material on how reeds operate, this how you make a latching reed relay. To release it you reverse the "strong" magnet. Edited January 17, 2022 by melmerby 1 Link to post Share on other sites More sharing options...
Theakerr Posted January 18, 2022 Share Posted January 18, 2022 Reed switches can be mounted on all 4 sides of the train and activated by magnets appropriately placed. Only problem can be some locos have magnets that are powerful enough to activate side mounted reed switches. I use Hall effect sensors (that are polarity sensitive) coupled to an Arduino, but I seem to remember seeing a circuit did not need an Arduino Link to post Share on other sites More sharing options...
cliff park Posted January 18, 2022 Share Posted January 18, 2022 The phrase 'Hall effect switch' is all embracing for a family of devices. The most basic can be thought of as a transistor which is turned on by a magnet. The more complex ones are integrated circuits which can include op-amps and latching circuitry. Even the basic one should be able to light an LED or operate a relay with the right circuit. Link to post Share on other sites More sharing options...
Joe MCMLXI Posted January 18, 2022 Share Posted January 18, 2022 Hi TeamYakima, I don't know how you would do this exactly, but I was thinking about something very similar, on an 009 layout I was planning, some years ago. My possible 'solution' was to have a Relay controlled by the polarity of the voltage to the loco. Then you could use the relay contacts to switch a supply to the reed switches that you wanted to be 'active', When the loco direction is changed, the polarity is reversed and the relay does not operate, so the supply is then switched to the Reed switches in the opposite direction.... Just a thought.... and not a proven idea, but someone with good electrical skills could probably make this work ? Joe Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted January 18, 2022 RMweb Premium Share Posted January 18, 2022 (edited) On 18/01/2022 at 20:46, cliff park said: The phrase 'Hall effect switch' is all embracing for a family of devices. The ones I bought were described as Hall Effect Sensor. OH49E & OH3144E The OH49E (analogue): OH3144E (Digital): 10 of each for £1.85 inc 44p* postage from China. *something to do with International Postal Union rules. Edited April 7, 2022 by melmerby Link to post Share on other sites More sharing options...
TEAMYAKIMA Posted January 19, 2022 Author Share Posted January 19, 2022 10 hours ago, Joe MCMLXI said: Hi TeamYakima, I don't know how you would do this exactly, but I was thinking about something very similar, on an 009 layout I was planning, some years ago. My possible 'solution' was to have a Relay controlled by the polarity of the voltage to the loco. Then you could use the relay contacts to switch a supply to the reed switches that you wanted to be 'active', When the loco direction is changed, the polarity is reversed and the relay does not operate, so the supply is then switched to the Reed switches in the opposite direction.... Just a thought.... and not a proven idea, but someone with good electrical skills could probably make this work ? Joe Good idea, but I don't think that would work with DCC Link to post Share on other sites More sharing options...
TEAMYAKIMA Posted January 19, 2022 Author Share Posted January 19, 2022 Hall sensors I have looked on ebay with the selection MAGNETIC HALL SENSOR and all sorts of things come up. I am not an electronics expert, what I am looking for is a device which I can stick up through the baseboard and it makes a single pole circuit when a north (or south) magnet passes over. I don't really want to have to make up boards from components - I would like a ready made selection but I have absolutely no idea what I'm looking at when I look at ebay. Help please Paul Link to post Share on other sites More sharing options...
Golden Eagle Posted January 19, 2022 Share Posted January 19, 2022 (edited) 21 hours ago, TEAMYAKIMA said: Hall sensors I have looked on ebay with the selection MAGNETIC HALL SENSOR and all sorts of things come up. I am not an electronics expert, what I am looking for is a device which I can stick up through the baseboard and it makes a single pole circuit when a north (or south) magnet passes over. I don't really want to have to make up boards from components - I would like a ready made selection but I have absolutely no idea what I'm looking at when I look at ebay. Help please Paul Then you need two Reed switches. If your locomotive turns around, PaulRhB and KevinLMS’ suggestion of putting a magnet at the side of the locomotive and positioning one Reed switch on either side of the track and triggering your effects depending on which switch activates. If your train shuttles back and forward without turning, you need to watch the order in which the Reed switches close. The former is straightforward. The latter is not complex, but would require some basic electronic design and construction skills (or use of something like an Arduino microcontroller…though that would (IMO) be using a sledgehammer to crack a nut). Edited January 20, 2022 by Golden Eagle Link to post Share on other sites More sharing options...
RMweb Gold PaulRhB Posted January 19, 2022 RMweb Gold Share Posted January 19, 2022 On 16/01/2022 at 22:59, TEAMYAKIMA said: One track is bi-directional and ideally I would like certain features triggered by clockwise trains and others by anti-clockwise ones. The original question suggest the simplest solution will work. On 17/01/2022 at 07:26, PaulRhB said: mount a small neodymium magnet on the right side of the loco so it only activates a reed on the right side of direction of travel. You mount two reed switches in the track, one by each rail. When it goes ‘up’ the magnet activates the reed on the right in the direction of travel. A loco travelling forward in the opposite direction will activate the other magnet. So a train travelling left to right, front first, activates the blue reed switch and a train travelling right to left activates the green one. 1 Link to post Share on other sites More sharing options...
Joe MCMLXI Posted January 21, 2022 Share Posted January 21, 2022 On 19/01/2022 at 09:42, TEAMYAKIMA said: Good idea, but I don't think that would work with DCC Ooops, sorry about that ! I did briefly look at the topic heading - my eyes briefly saw ( Electrics - Non DCC ) and away typing I went ! Good look with your project TeamYakima Link to post Share on other sites More sharing options...
Crosland Posted January 21, 2022 Share Posted January 21, 2022 On 16/01/2022 at 23:36, melmerby said: Isn't there a chance they would stick on? Two reeds in quick succession sounds the best idea to me Followed by a Horned Viper and a length of Twisted Flax. Sorry, I'll get my coat... 2 Link to post Share on other sites More sharing options...
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