Philip

F1p Train Optical Detection

32 posts in this topic

Hi Philip

Instead of relying on ambient falling on the sensor, why not shine light on to the sensor, e.g. yard lamps. or even use an ambient light detector to turn on the additional lamps when the light level drops.

Another way would be to use current detection instead of light sensors, or glass reed switches these however would need a magnet fitting to each loco.

You can use the I2C on both the Pi and Arduino to talk to each other, but watch out for voltage levels, the native voltages for the arduino is 5V the Pi is 3.3V, you will need to make allowances for this in your interfaces.

On my DCC layout I will be using a combination of MERG current detectors, and MERG pocket money kit No.7 DCC occupancy detectors. These would both work with your circuit as input devices in place of the light detector.

Paul

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Hey Paul,

Thanks for the feedback - absolutely this was unfortunately a bit limiting and had an insane amount of maths to compensate for varying light levels. An IR detector/receiver would of been good too, but didn't fit between the sleepers as snugly and invisibly as this.

What about an RFID based? Has some disadvantages again, but could even tell which loco was above it.

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RIFD is certainly doable, but could turn out expensive depending on the number of readers you need to install. Check out both JMRI and MERG. MERG do RFID kits, and JMRI integrates these into the software. Not tried them myself, when your layouts only 11ft long I can almost remember the numbers myself - need glasses to see them tho :rolleyes:

Just thinking about it, why not have a second reference detector nearby, that the inputs could be compared with, e.g. If A1 = A2 then track empty, if not = A2 then track occupied, where A1 is the track sensor, and A2 is nearby with ambient light falling on it.

Paul

Edited by paul_l

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Thanks for the info Paul,

Bit shocked at the price though! £30 for a starter kit. 

Can get Arduino RFID stuff for about £3 on ebay. (would need some modding to make it compact)

 

Both would need laying the received pad under the tracks as well.

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Hi Phillip

And it only really becomes useful if you tag all the other vehicles. That way the PC dobs you in if you forgot to pick up the correct vehicles - or even have them in the wrong order :rolleyes:

Part of the problem, is scanning distance, and time, as the target is small and moving quite quickly.

I'll stick with current detectors and reed switches for the moment

Paul

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Hi Phillip

And it only really becomes useful if you tag all the other vehicles. That way the PC dobs you in if you forgot to pick up the correct vehicles - or even have them in the wrong order :rolleyes:

Part of the problem, is scanning distance, and time, as the target is small and moving quite quickly.

I'll stick with current detectors and reed switches for the moment

Paul

Yeah would agree, was thinking would need to tag everything to make the most out of it...

I can't think of a neat & simple way to tag loco's currently. Perhaps in the future, but reed switches are probably the most reliable although can look a bit clumpy unless well disguised. 

 

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If you were using DCC, then block detection using current sensing may well be the way to go, worth looking at MERGs Pocket Money Kit number 7, and Kit 56 8 channel detector.

I will try and post a how to on the builds of them later.

Paul

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