occupancy detection circuit - MR Mag May 2015 pg 56

[gregc]

Actually Greg, that would all be fine by me.
Draw me up a full circuit with exact values on stuff and mix the two circuits so I have a green/red indicator.

My schematic from 4/25 7:50 AM shows component values except the LED resistors which you'll have to select based on supply voltage and desired brightness. i used 2n22222a transistors (50 for $1 ebay), but I believe any general purpose NPN transistor, such as an 2n3904 or whatever is popular these days will work.

I'd suggest trying everything out on a proto-board first before soldering anything.

 

[Rich_Ros]

I haven't studied this circuit yet, but it sounds like 50 year-old technology and is both complex and expensive. I tried some time ago to introduce here an inexpensive RR crossing flasher with track detectors but was met with hostility and accusations of lying, cheating and almost of shooting JFK, J.R. and Roger Rabbit, all with no foundation whatever. All I tried to do was help modelers dress up their layouts with high performance technology at a very low price. One of the regulars on this forum actually tried one and seemed pleased with it but didn't seem to want to share... ( Refer to the "Dynamic Scenery" thread.)

That basic flasher can be re-configured to serve as a track detector in several ways. It can be configured to shoot a shallow angled beam across the tracks spanning over at least 5 feet and can operate with multiple beams to cover longer distances. A second version works with sensors embedded in the track (above board) and can use multiple sensors along the track to provide better coverage. A minor software change on my part and it can provide a red/green occupancy signal rather instead of the flasher function. The circuit runs off 5V but includes a regulator to operate from 6 to 18 volts DC. The circuit is actually very simple, a little 8-pin micro with almost no other components. The sensors are IR and are
automatically compensated for ambient light conditions.

If you have the courage to consider modern technology I'd be glad to work with you. Feel free to contact me with any questions you might have. I have a web-page but I don't know if it's allowed in this forum.

Rich

>>>>>>>>>>>>>

there are some errors in the schematics of that article, such >>> snip

the trade off with embedding an optical detector in the track the way they describe is that it only detects the presence of something over that spot on the track. An alternative would be mount a photo detector and light (or infra-red LED) source above and on opposite sides of the track at an angle such that the light path is horizontal and crosses a large length of track. Anything breaking the path would be detected.
<<<<<<<<<<<<<<<<<<<<<<<<<<

 

[trailrider]

If you just like making circuitry such as this, great! But block occupancy, crossing signal flashers and bells, and a bunch of other things can be easily done with commercially available IR (infra-red) products, such as the units available from Azzatrax and others. Depending on the availability of space under the tracks (in which case the IR emitter and receptor can be placed between the rails) or above the surface of the layout, so the IR beam goes across the tracks. These units are, by today's standards, pretty reasonably priced, DO NOT require track power, and can be powered by a separate AC or DC source, so DC or DCC or DCS are immaterial. The advantage of the IR systems is that you can use them in "daylight" or "night" operations. Just sayin...

 

[Rich_Ros]

Hi trailrider

I find it amazing that so many can decide that commercially available products are so much better than what I'm offering and are reasonably priced. How can you know that when you know nothing about what I offer and have no logical basis for comparison. Maybe you think $40 for a flasher and another $50 plus for sensors is reasonable, but do you know what my kit would cost? Do you know the meaning of the term 'ambient light compensation' and it's importance to the modeler? Do you know if it's included in that higher priced product? Did I not explain how the reflective sensors that I use are embedded it the cork roadbed between the ties? Do you know if that high-priced system can reliably span a 5 foot section? Oh, I forgot to mention that I include 30 AWG wire that can be tucked under the edge of the cork roadbed and everything can be build above board. Have you listened to the sound of the bells that are "reasonably priced" and compared it to mine that are a $6 add-on?

I would never question your skills and knowledge about model railroading, please have some consideration for my skills in electronics and microprocessor applications. I see a lot of high-priced stuff out there and I see a lot of model railroad people that might like to dress up their layouts but can't afford all the 'reasonable prices' that are available from the 'big guys'. Why don't you work with me, give my designs a fair evaluation, and pass the word onto all your friends in this community?

Am I allowed to include a link to my web-page on this forum?

Rich

p.s. I took a look at the Azatrax installation instructions and noticed that they actually recommend connecting the LEDs in parallel! That is bad design..... By the way, I control two LEDs independently with just two wires, that's pretty important when you're building your own light assemblies and trying to hide the wires. Have you seen anyone else that can do that?

 

[gregc]

If you just like making circuitry such as this, great! But block occupancy, crossing signal flashers and bells, and a bunch of other things can be easily done with commercially available IR (infra-red) products, such as the units available from Azzatrax and others.

Just sayin...

yes, I like building circuits. It's a facet of the hobby, just as some modelers are very interested in handlaying track and turnouts or scratch building structures or even locomotives, all available commercially.

But there are several advantages to building your own circuits:
- learning to repair them
- learning about different ways to solve similar problems
- building just the circuit you need
- learning about electronics and a skill that could be used outside of modeling or as a potential career
- saving money

the problem with the MR article was that had it had mistakes and the design could have used less expensive parts (pennies instead of dollars) and demonstrated more interesting electronics. And because of this it is more likely to discourage than encourage people to try building circuits.