Large Scale Central

Block Detection

Electronics
#21
Bob McCown said:
Anyone know the effective range of a photo transistor/irLED pair? Would I be able to use it over a span of say 10" to detect a 1:20 train in between?
The range should be OK as long as no daylight gets into the equation. Infra red does not work well in daylight. Fantastic range at night.
#22

Hmm…thanks Tony… .I think Im going to need to build some sort of aimed ir, or use simple photocells or something. I have block detection working on sections of track, but since switches are all one big connection, I cant detect rail-to-rail, so I was hoping to use some sort of visual detection. Guess its time to experiment!

#23

I use visual detection on my layout.

Oh look! There’s a car I forgot to bring in…over there on that siding!

#24
TonyWalsham said:
Bob McCown said:
Anyone know the effective range of a photo transistor/irLED pair? Would I be able to use it over a span of say 10" to detect a 1:20 train in between? .
. The range should be OK as long as no daylight gets into the equation. Infra red does not work well in daylight. Fantastic range at night. .
. You should be able to set up some sort of IR detection inside a tunnel.

Tony, how much shade does one need? Would a laser work, or even be practical?

These are the musings of someone who is electronically challenged.

madwolf

#25

What I need the IR (or other) detection for is for switches. I can detect cars on regular track no problem, but most of my switches aren’t electrically isolated rail to rail, they’re one big circuit, so I cant detect that way. I was going to use some sort of ‘car-in-the-way’ circuit to detect whether a car is over the switch or not, but I need a range of 8-10 inches. Hmm…

#26

How about shading the IR led and reciever with a shield? or lack of voltage on a solar panel under the track when a car is parked. Yard lamp over it at night.

#27

I also saw somewhere a short brass tube with a very light wire inside, insulated at the bottom. With the light wire protruding from under the track an axle would brush them together completing the circuit.

#28
Bob McCown said:
What I need the IR (or other) detection for is for switches....I need a range of 8-10 inches. Hmm...
I seem to remember reading some years back about a home-built system where the emitter and detector were mounted in black plastic tubes (I forget the length) to keep stray light to a minimum. The system did require careful lining up. It wasn't outdoors, either.