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Topic: Detecting each of up to 16 different things (Read 4846 times) previous topic - next topic


Well, you said you didn't want obvious red barcode scanning light.
You wanted non-powered/passive ID for each car.
You were worried about identifying the start/end of barcodes/optical things on cars.

Adafruit is not the only source for tag readers.
If something else comes to mind I'll put it up here.

Thanks, CrossRoads.


Only the detector needs a tube if that. Put it behind an aperture. In the mid-80's at a Trenton Fest I saw some guys who made a scanner out on a dot-matrix printer. They mounted the light sensor in a pointed pen barrel and got recognizable images. The IR is just for illumination.

Depending on train speed you may be talking 1" long strips. You might try printing flat black stripes on silver reflective material and see if they have that on sticky-back sheets.

I'll have to dig out my old spectrum and thermal printer to get flat black on 'silver' paper. It won't be sticky-back, though :D
Joking aside, a thin glossy white card would probably be reflective enough. I may be able to fit up to about 2" long strips. Train speed will be at a crawl, the scaled down (1/76)equivalent of about 3 - 4MPH (walking pace).

If you know what a hump-shunting yard is, I'm trying to automate one with 4 sidings, to sort a jumble of 16 wagons into numerical order.  On the first shunt, siding 1 will get wagons numbered 1,5,9 and 13, siding 2 will get wagons numbered 2,6,10 and 14, siding 3 will get wagons numbered 3,7,11 and 15 and siding 4 will get wagons numbered 4,8,12 and 16. The loco will then pick up all the wagons in sidings 1 to 4 and again hump-shunt them. This time, siding 1 will get wagons numbered 1 to 4, etc.,etc. The wagons will then be in numerical order when the loco picks them up for the second time, no matter what order they started in.
This will give you some idea of what I'm trying to acheive.


IR reflectivity, you might be able to test with a webcam, but might have to modify it.

I note with my webcams and cheap DVR camera that a red led shows bright white even dimmed, there's so much IR from the led it overloads the sensor. I used webcam to check if my IR's really were lighting when I was having trouble with a circuit, they look white.

With -enough- IR, a cheap webcam might let you check reflection test patches quickly given strong IR lighting and shading the patches from direct room light. If you can see the difference with a webcam, an IR detector should be affected too.


You might try that anyway. You could run the trains in shade or dark with IR spots to make night train movies. (okay, sorry, just could resist)

Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts


IR reflectivity, you might be able to test with a webcam, but might have to modify it.

I've read that mobile [cell] phone cameras will also do that, without modification.

Talking of night scene filming, there's a model railway here (Pendon, Oxfordshire, UK) part of which has a model man leaning against an outhouse, smoking a cigarette. When they dim the lights for the night scene you can see the end of the cigarette glowing. Now THAT'S dedication to modelling!

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