Joined: 23/02/2005(UTC) Posts: 801
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Hi, In a past topic, PierreGillard gave an interesting link to Rapido train cars. Those cars lights are powered with battery, and the light is switched ON / OFF with an external magnet. That gave me an idea to add a tail light to my freight train. In fact, I can't use a slider in my last wagon, for current is used for position detection in my PC controlled layout, and the distance between current detectors at each end of a section is smaller than the freight train lenght. One solution is to use a slider in the first wagon and use current conductor couplers also for my good train. Quite expensive! I then use a 1.5V battery and switch magnet in my tail wagon. The switch magnet is made as follows: A reed contact is glued in the wagon and a magnet is glued at such a distance that if the reed contact is closed, it stays closed, and if it is open, it stays open. This is possible thanks to the hysteresis property of that magnetic circuit. If now an external magnet is getting near the wagon, depending of the position of its poles, it closes the reed contact if its magnetic field is in phase with the internal magnet, and open the reed if its magnetic field is opposite to the internal magnet field. The result is very good, and the initial reed-internal magnet distance is not difficult to find, and not very critical. For me the difficulty was to build the Weinert lantern: too small for my big fingers. I used: Weinert 4201 tail light Viessmann 6209 lamp (1.5V, 1.3 mm diameter) magnet from marklin (7556) Reed switch: Don't remember for it is 20 years old, but any reed switch will do.    Fred Edited by moderator 11 January 2011 23:06:18(UTC)
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Joined: 21/10/2004(UTC) Posts: 31,704 Location: United Kingdom
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Large Marklinist 3- Rails Layout with CS2/MS2/Boosters/C-track/favorites Electric class E03/BR103, E18/E118, E94, Crocodiles/Steam BR01, BR03, BR05, BR23, BR44, BR50, Big Boy. |
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Joined: 26/10/2004(UTC) Posts: 461 Location: Bruges,
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Simple but ingenious, using the hysteresis of the reed switch to keep it in position! Thanks for the tip, I'll try that one day too.
How long does the battery last? Wouldn't the lower consumption of a LED (instead of a bulb) prolong the battery life a little? |
Kind regards, Pieter-Jan Bruges, Belgium. |
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Joined: 23/02/2005(UTC) Posts: 801
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The battery should last 80 to 100 hours. Should be enough for me. Otherwise, I will use rechargeable battery with a small connector under the wagon for recharging. LED is another possibility, but 1.5V battery is generaly not enough: 2 batteries (3V) are then needed.
Fred
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Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway
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Good idea, Fred.
Thank you! |
Best regards Svein, Norway grumpy old sod
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Joined: 10/01/2005(UTC) Posts: 1,025 Location: Den Helder, Noord-Holland
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Nice idea Fred. I am relatively stupid as electronics are concerned, so I do not know whether this "white LED-on 1.5V" circuit draws more energy from the battery than a bulb does. Jeroen |
Figomima division, UP; mostly figment of my imagination yet. |
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Joined: 23/02/2005(UTC) Posts: 801
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Hi Jeroen, That circuit allows using a LED with 1.5V battery thanks to a small DC-DC converter increasing the battery voltage. Difficult to say what is the consumption. A very rough calculation: If the LED is a 5 mA/ 2.4V, and assuming the DC-DC converter fits well the LED needs (  ) ; Assuming 10% loss in inductance and transistors, and 4mA static consumption of the converter, we get: I= 5*2.4/1.5/0.9 + 4mA= 12.9 mA, instead of 30 mA for bulb. Please take that as an order of magnitude for there are many assumptions! Fred
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Joined: 08/11/2005(UTC) Posts: 3,528 Location: Mullerup, 4200 Slagelse
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If you can dream it, you can do it! I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide. In case this is not legally possible: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.  |
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Joined: 21/10/2004(UTC) Posts: 31,704 Location: United Kingdom
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Quote:[size=1" face="Verdana" id="quote]quote:Originally posted by efel <br />The battery should last 80 to 100 hours. Should be enough for me. Otherwise, I will use rechargeable battery with a small connector under the wagon for recharging. LED is another possibility, but 1.5V battery is generaly not enough: 2 batteries (3V) are then needed.
Fred
Very good,thanks for the information and tips. |
Large Marklinist 3- Rails Layout with CS2/MS2/Boosters/C-track/favorites Electric class E03/BR103, E18/E118, E94, Crocodiles/Steam BR01, BR03, BR05, BR23, BR44, BR50, Big Boy. |
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Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway
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I would think that 1,5 volts should be enough to make a LED bright enough for the rather low light intencity required for a tail-light? At that low voltage the current consumption should be rather low.
Otherwise, two rechargable batteries will give 2,4 volts, as a normal rechargable cell is 1,2 volts. |
Best regards Svein, Norway grumpy old sod
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Joined: 23/02/2005(UTC) Posts: 801
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Hi Svein, None of my LED worked at 1.5V. Of course, it doesn't mean that NO LED works at that voltage, but very often the LED makers don't give the voltage characteristics, and the LED characteristics I have don't show any light intensity at that voltage. I really would like to find such LED, and any input would be appreciate.
Fred
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Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway
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Thanks, Fred Anyhow, I have to check when I return back home  |
Best regards Svein, Norway grumpy old sod
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Joined: 06/02/2005(UTC) Posts: 1,383 Location: Darmstadt,
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Very good and clever idea! Using the hysteresis of a reed contact is perfect.
I was always looking for a such a simple method to switch car lights on and off without complicated electronics.
Hans Martin
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Joined: 23/02/2005(UTC) Posts: 801
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Hi, Thanks all for your kind comments. I must say that using a reed switch and a magnet as a bistable relay, thanks to the hysteresie property, is not at all my invention. What surprised me is the ease with which things were done and worked at the first attempt, without difficult adjustment. And this topic is aimed at encouraging the forum members who are tempted, to try their luck!
Fred
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Joined: 04/12/2006(UTC) Posts: 338 Location: Doylestown, PA
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The magnet appears to be the magnet that comes with set decoder/motor set 60760. That magnet is the one between the two halves of the rotor surround (sorry- don't know the actual terms used for these components.
Jim
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Joined: 23/02/2005(UTC) Posts: 801
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In fact the magnet I used is a M7556 (first post updated), but any other small magnet would work.
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Joined: 23/02/2005(UTC) Posts: 801
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Quote:[size=1" face="Verdana" id="quote]quote: Originally posted by efel<br /> A very rough calculation: If the LED is a 5 mA/ 2.4V, and assuming the DC-DC converter fits well the LED needs (  ) ; Assuming 10% loss in inductance and transistors, and 4mA static consumption of the converter, we get: I= 5*2.4/1.5/0.9 + 4mA= 12.9 mA, instead of 30 mA for bulb. Please take that as an order of magnitude for there are many assumptions! Hi, I made some simulations of the schematic given @ http://www.circuitsonline.net/circuits/view/122The current consumption is very large. With some modifications, it's possible to get a 4 mA consumption from the battery (1.5V) for a 2mA LED. Fred
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Joined: 24/12/2006(UTC) Posts: 79 Location: Lisbon,
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Hi Efel,
can you send me a picture and a diagram with all the components inside the wagon? I'm a newbie regarding MRR as well as in electronics subjects, but I would like to try to implement your idea!
thanks for your support! Ayala
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Joined: 23/02/2005(UTC) Posts: 801
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Hi Ayala,
All the components are on the pictures above: 1battery, 1 Reed relay, 1magnet , 1 bulb + 1 lantern if the wagon does not have one. The part numbers of the components are also in my previous posts.
As you can guess, the diagram is quite simple: Starting from the battery, connect the + to 1 electrode of the relay. The other relay electrode is connected to the lamp and the other electrode of the lamp is connected to the - of the battery.
To find where to place the magnet: bring the magnet slowly to the relay until the lamp is ON=position 1. Then move very slowly the magnet away until the lamp is OFF= position 2. Glue the magnet in its final position i.e. between position 1 and 2. Now approaching another magnet (outside the wagon), depending of its pole position (!), you can switch the lamp ON or OFF.
Have fun!
Fred
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