RMR017 - Train detection via reed switch and magnet
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- Опубліковано 10 жов 2014
- With a digital model railway train detection (block signaling) is an important function. Most often current sensing is used. It is quite reliable and you don't have any (ugly and non-prototypical) sensors in view. The drawback is that it probably also is the most expensive method.
I like to try out some different sensing methods. Just for fun ... but also because I like to use the Arduino for S88 sensor feedback, which can reduce cost by a factor of 5 or more!
This video covers the use of a reed switch and a magnet glued under the loc. Optical detection has been discussed already, see video RMR013 for that.
More info on my blog: rudysmodelrailway.wordpress.com/ - Навчання та стиль
Have you thought about Hall Effect detectors? They are even smaller than reed switches (the same size as a small transistor), are a lot less fragile and can be easily hidden under ballast.
They need more wires (Power, GND, Data), which is why I chose not to use them. The size of the reeds is OK for me. If wanted, the reeds can be placed vertically, in a hole, then they are entirely invisible.
Great explenation Ruud. Where do you get the reed`s and magnets for the price you mention in the video.
Best regards JC
Have you considered a Hall Effect device? Very small and therefore unobtrusive and a quite small magnet fitted to the underside of the train. Requires 2 wires:: ground and signal, assuming there is a pull up resistor somewhere. Hall effect devices have hysteresis so only one signal as the train passes.
If you like them they definitely are an option. I did not need their small size (by the way, the reed can be mounted vertically, in a hole, you won't see it) and since there is an extra 5V wire involved I chose reeds for simplicity.
What's the practical working distance between the switch and magnet? Could you place the switch below track level (channel carved out of the cork or other roadbed)? Even further below that? How about magnets placed in rather than under cars/locos?
Curiosity as much as anything I guess! Though that might be important if you're adding this to existing rather than new construction. Thanks for the quick reply and helpful videos
Hi Rudy thank you for posting
I am attempting to create a moving coaling Tower for the new Goodison Road
I use iTrain control system with voltage drop detection
I haven’t used momentary feedback detection yet but would like to try it for reed switches top and bottom of the guide rails which the wagon lift works on - the winch being controlled by a zimo loco decoder - the idea is to write a short script or action in iTrain to move the lift up and when hits reed switch it will stop, wait a time then descend and stop at the bottom at the lower reed switch
Question is - these boards are they useable straight out of the bag or is there a skill required to program the board first as I’m not really specialist that way - thank you JC
The question is what interface you use to connect your detectors to the PC with iTrain?
Rudysmodelrailway hi there - I have a digikeijs DR5000 command station - and use intellibox loconet protocol over usb to a Mac using macOS Catalina
My voltage drop detectors are all Digikeijs DR4088LN over loconet
Cheers JC
Rudysmodelrailway I have seen Digikeijs DR4088 OPTO which seems to do the same as the Arduino but is approx €50 - but has 16 inputs? JC
If you still have some inputs available on your 4088's then you can connect reed switches with a series resistor like you connect a piece of track, a current will flow and that will be detected. If no free inputs are available a new Loconet detetction module is needed. A cheap alternative to the commercial unit is ARCOMORA Arloco (just Google it). You'll need an Arduino ($3,-) and you need to solder the Arloco shield ($5,-) yourself.
You mention the current sensing is much more expensive, but the same Arduino (with the integrated ADC) could be used to do the same. With no external components. Maybe if you want to get fancy just an on-board (on Arduino, not onboard train lol) op amp
Indeed using Arduino plus current sensing electronics is a cheap solution. www.arcomora.com
Drill a hole vertically between the rails to install the reed switch in, then only the wire is visible.
Reed switches operate best when they are parallel to the magnetic field. If they are vertical, they may not work.