Pete the Elaner Posted December 17, 2018 Share Posted December 17, 2018 This was brought up in another thread but I think it deserves its own. I am interested in producing a spark when a 3rd rail trains passes a certain rail junction. These are caused by the shoe breaking contact with the conductor rail, so it happens at the same point on the track. I am therefore looking at mounting a bright LED in the baseboard & finding some way of firing it when the shoe of a 3rd rail until passes over, but not when a diesel does. Firing the LED should not be a problem although a suggestion of how to do it will save me from having to work it out but does anyone have a recommendation of a cheap, reliable, readily available way of detecting when a conductor shoe passes over so the LED fires at just the right time? Although I use DCC, I don't think this is relevant. Link to post Share on other sites More sharing options...
WIMorrison Posted December 17, 2018 Share Posted December 17, 2018 Could you not fit a small neodymium to the electric locos that you want to spark and have the magnets close a reed switch at the appropriate place? 1 Link to post Share on other sites More sharing options...
Arun Sharma Posted December 17, 2018 Share Posted December 17, 2018 Look on the Radley Models website. Details of how to get sparks from conductor rails are on the website Link to post Share on other sites More sharing options...
NIK Posted December 17, 2018 Share Posted December 17, 2018 This was brought up in another thread but I think it deserves its own. I am interested in producing a spark when a 3rd rail trains passes a certain rail junction. These are caused by the shoe breaking contact with the conductor rail, so it happens at the same point on the track. I am therefore looking at mounting a bright LED in the baseboard & finding some way of firing it when the shoe of a 3rd rail until passes over, but not when a diesel does. Firing the LED should not be a problem although a suggestion of how to do it will save me from having to work it out but does anyone have a recommendation of a cheap, reliable, readily available way of detecting when a conductor shoe passes over so the LED fires at just the right time? Although I use DCC, I don't think this is relevant. Hi, I am working on such a device for a club layout which presently uses a bit of aluminium foil strip as a reflector under the bogies and aligned with the third rail shoes. An infrared beam from an IR LED behind the front running rail points up at the bogie. An infrared photodiode with shroud and next to the LED looks up for the reflected light. A microcontroller (currently an Arduino clone from China costing £1.50) turns the IR LED on and off very quickly and compares the ambient light to the reflection. If the difference is above a certain threshold for a certain period it decides whether its the aluminium foil that's doing the reflecting and if it thinks it is triggers the third rail flash. As its an off ramp flash (the big one when a train is accelerating) it produces a big flash (increases quickly, jitters a bit) and then tails off and has little very short random pulses for a short while to represent the tiny hot bits of pick up shoe? left behind. The unit drives a high power Surface Mount LED (white with a hint of Blue) mounted in a tiny socket behind the third rail where the off ramp starts to dip down. I was going to use magnets on the bogies and Hall effect sensors mounted under the ballast but I couldn't work how to tell those magnets from the magnets used on locos for DCC Concepts Powerbase within the variable times the magnets were within range depending on train speed. In the future I'm hoping to enable the third rail flash units via train identification using 13.56Mhz RFID so that the third rail flash unit cant do a miss fire if it accidently triggered on something under a non electric train (or maybe it could be extended to electrodiesels in diesel mode). Regards Nick 1 Link to post Share on other sites More sharing options...
Ray Von Posted December 17, 2018 Share Posted December 17, 2018 I have done this using a set of Heathcote circuits and reed switches (see my blog, I've just added an entry, I think it could interest you.) I'm pleased with them, but a word of advice - the reed switches are very fragile and the LEDs are blue, not bright-white. The effect is good, but might not be as impressive as expected... Link to post Share on other sites More sharing options...
Guy Rixon Posted December 17, 2018 Share Posted December 17, 2018 If the reed switches are giving grief, could you replace them with hall-effect switches? Is that affordable now? Link to post Share on other sites More sharing options...
Pete the Elaner Posted December 18, 2018 Author Share Posted December 18, 2018 I have done this using a set of Heathcote circuits and reed switches (see my blog, I've just added an entry, I think it could interest you.) I'm pleased with them, but a word of advice - the reed switches are very fragile and the LEDs are blue, not bright-white. The effect is good, but might not be as impressive as expected... That's interesting. I like the way you've hidden the switch beneath AWS ramps. I can't do that because my layout is pre-war 4th rail, but the 4th rail & some 'grot' in the 4 foot could hide it a little. Would this make the switch too far from the passing magnets for them to work? Link to post Share on other sites More sharing options...
Ray Von Posted December 18, 2018 Share Posted December 18, 2018 The switches are very sensitive and the magnets (neodymium) are very strong. During testing of the setup, I was able to activate the LEDs by holding the magnets several centimetres (feet in "N" gauge!) over the reed switch. Link to post Share on other sites More sharing options...
Pete the Elaner Posted December 18, 2018 Author Share Posted December 18, 2018 The switches are very sensitive and the magnets (neodymium) are very strong. During testing of the setup, I was able to activate the LEDs by holding the magnets several centimetres (feet in "N" gauge!) over the reed switch. That's great. I have caught a bit of a bug for assembling electronic kits right now so I'll probably give this a go. Link to post Share on other sites More sharing options...
Ray Von Posted December 18, 2018 Share Posted December 18, 2018 You may well be able to remove a few sleepers, fit the reed switch, add ballast around it and then replace the sleepers with thin plastic strips. I'd try it on a spare bit of track section first though. 1 Link to post Share on other sites More sharing options...
dasatcopthorne Posted December 18, 2018 Share Posted December 18, 2018 This was brought up in another thread but I think it deserves its own. I am interested in producing a spark when a 3rd rail trains passes a certain rail junction. These are caused by the shoe breaking contact with the conductor rail, so it happens at the same point on the track. I am therefore looking at mounting a bright LED in the baseboard & finding some way of firing it when the shoe of a 3rd rail until passes over, but not when a diesel does. Firing the LED should not be a problem although a suggestion of how to do it will save me from having to work it out but does anyone have a recommendation of a cheap, reliable, readily available way of detecting when a conductor shoe passes over so the LED fires at just the right time? Although I use DCC, I don't think this is relevant. Express Models. Dave 1 Link to post Share on other sites More sharing options...
dasatcopthorne Posted December 18, 2018 Share Posted December 18, 2018 See this discussion. http://www.rmweb.co.uk/community/index.php?/topic/83341-third-rail-arcing-circuit/ Dave 1 Link to post Share on other sites More sharing options...
Ray Von Posted December 18, 2018 Share Posted December 18, 2018 See this discussion. http://www.rmweb.co.uk/community/index.php?/topic/83341-third-rail-arcing-circuit/ Dave There is some good advice on here too : http://www.rmweb.co.uk/community/index.php?/topic/139879-arcing-effect-in-n-gauge/ it was of great use, particularly in "N" Gauge, when I was approaching this as a project. 1 Link to post Share on other sites More sharing options...
Ouroborus Posted January 6, 2019 Share Posted January 6, 2019 I've been working on the same thing but using an arduino. This would be happy on DC or DCC. It uses a Hall sensor in the track (ignore the massive one in the video - this was just a proof of concept) along side an LED. Magnets are glued to the underside of electric locos and units. As the magnet passes the sensor, the program starts, firing the led for a long burst, then a couple of shorter ones. You can vary the time and interval between these and adding another sensor circuit requires a little more than a copy and paste of the code. Without a magnet, there is no trigger to start the program, so steamers and diesels should not start it. I know this may sound complicated and expensive, but what you're looking at in the video cost less than £8 and adding further sensors and leds costs pennies. The coding is the harder part. I'm new to coding and have used 'delay' to do this effect, which is a rather clumsy way around. If anyone wants to have a look at my code and advise, i'd be happy to paste it up here. https://www.youtube.com/watch?v=iT_BMZlSwBU Thanks. 1 Link to post Share on other sites More sharing options...
Ouroborus Posted February 3, 2019 Share Posted February 3, 2019 Further to my previous, this is a test fit of the hall sensor and led in the track bed. Detection seems to be reliable, but the arc-ing is too slow and too long, with it continuing after the loco has passed when running wrong line. Fortunately, that's a relatively easy adjustment in the Arduino and I'll shorten the overall duration and bursts 2 Link to post Share on other sites More sharing options...
Paul80 Posted February 4, 2019 Share Posted February 4, 2019 (edited) Slightly off topic but any moons ago I remember reading that the ability to trigger a bright LED to simulate the pickup ark was included in the features of ESU sound decoder which also allowed a sound of the Arking to be played as well, from memory (which is not to good these day's) it was whilst they were still on v3.5. The LED was mounted on the loco, obviously then just flashed at random points and played the arking sound in sync with the flash. Is that correct and can it still be done with their v4 and the new v5 or is my memory playing tricks Edited February 4, 2019 by Paul80 Link to post Share on other sites More sharing options...
AMJ Posted February 4, 2019 Share Posted February 4, 2019 If you are modelling 4 rail power supply would it be feasible to have operational pickups for the 3 & 4 rails on the motive power? All you will then need to do is for the 3 & 4th be connected by a wire to create the circuit for the LED flash. If it fails to make then this gives even more randomness. Link to post Share on other sites More sharing options...
Ouroborus Posted February 4, 2019 Share Posted February 4, 2019 What I was keen to avoid with my setup was steamers and diesels triggering the led. With hindsight, you could mount the led in the loco and the trigger in the track. (Or via DCC). But I didn't rate my modelling skills to achieve this Link to post Share on other sites More sharing options...
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