Long wires to transistor base a problem?

[LKO Railroad]

Interesting - What's the purpose of the 5 stacked tracks?  - and where do the sensors you're making fit in the picture?

The 5 stacked tracks form a helix which serves as a train elevator to move trains from one level to another on a multiple level train layout.

The sensors mount on the wood blocks (red arrow) pointing outwards.

[LKO Railroad]

LED's emit some light out their side, so I'm hoping you have something between the emitter and detector rows to prevent this. Like a small opaque piece of thin plastic. Or maybe do a quick test to see if LED on/off with no reflection makes too large a difference.
Are the track runs in a tunnel or something, where's the re-railers lol.

Completed units will have black heat shrink on the emitter. I haven't made it that far yet on the production pieces. Here are pics of the prototype unit with heat shrink installed and wire separators on the backside.





No re-railers needed. Track is properly laid.

[LKO Railroad]

Are you making a railway version of the Large Hadron Collider?

Sort of. A head-on collision in the helix would produce a lot of train particles! 

[SilverSolder]

Interesting - What's the purpose of the 5 stacked tracks?  - and where do the sensors you're making fit in the picture?

The 5 stacked tracks form a helix which serves as a train elevator to move trains from one level to another on a multiple level train layout.

The sensors mount on the wood blocks (red arrow) pointing outwards.

(Attachment Link)

Why so many sensors -  are they used to detect the length of the train or something?

[LKO Railroad]

Why so many sensors -  are they used to detect the length of the train or something?

There are so many sensors because they are spaced 1-1/2 car lengths apart. An average car is 200mm long. The helix track length is 22 meters. The pulse stretcher is long enough to allow a car to make it to the next sensor before the first sensor times out even at slow train speeds. This keeps the panel display a single contiguous line of lit LEDs showing the location, length, and movement of the train as it climbs or descends the helix without any of the panel LEDs blinking.

[dietert1]

It's something like a camera, isn't it? This reminds me of a project i was involved about 30 years ago, about reading the level of blood probes. There was a robot to handle the tubes and it could pass the tube through a ring with 5 LEDs and 5 photo diodes to find out the level of the liquid inside. Nowadays one would do it with a video camera and a smart AI system. How times have changed.

Regards, Dieter

Edit: Just found the first prototype. Actually it had 12 LEDs and 12 photo diodes, with modulation and demodulation. The black ring is an optical mask with 24 1mm holes and served to sharpen the image. At the time it was used with an 8 bit micro to digitize the data and perform some pattern recognition.

[harerod]

Dieter, there is hope! A while long ago a design left my lab, which is not too different from what you described, albeit bound for space. Of course one could call that a niche application.
With Chipageddon upon us, we will have to remember how to solve problems with basic general purpose components. Maybe this whole debacle presents a chance to transfer know-how to a younger generation of engineers.

[floobydust]

I thought a re-railer is mandatory in tunnels, of course the track is flawless but any bump or jar can knock a truck off the track. If you can reach in the backside to fix, I guess it's OK.
What gauge is this? Curious what 22m works out in scale length.

[LKO Railroad]

I thought a re-railer is mandatory in tunnels, of course the track is flawless but any bump or jar can knock a truck off the track. If you can reach in the backside to fix, I guess it's OK.
What gauge is this? Curious what 22m works out in scale length.

Re-railers are common on toy train layouts, less so on scale model layouts. There is low probability of derailment on helix track. The overwhelming majority of derailments occur on switches, diamonds, slips, and other similar more complex trackwork of which the helix has none. There is however, a possibility of string-lining a train if the consist makeup is wrong (empties up front, loads in the back). That's operator error.

The entire inside of the helix will be accessible. Only certain portions of the outside are difficult to access. Round helix sitting in square corner.

This is HO scale - 1:87
22m = just shy of 2km

[LKO Railroad]

Promised to keep you abreast of the progress. Completed six of these boards. Each board contains ten detector circuits. Each detector circuit has two inputs. Each input has three IR pairs.

[LKO Railroad]

Aborted the central board idea and went with individual sensors. Works great! Thanks for your help.