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Discussion Starter · #1 ·
A day early this week, to make up for being a day late last week and because I am taking tomorrow "off from everything" and making a long weekend a mini-vacation.

The video link below shows the traffic control system on my Main Street working. What you see at the beginning is one of the fastest cars I have (yellow/white '56 Ford) riding the tail of one of the slowest ('48 Cadillac), then a traffic control block stops the Ford to let the Caddy get farther ahead. The Ford stars again when the Caddy gets 36 inches ahead of it, and because it runs much faster, it begins to catch the Caddy again. As the cars finish the turn-around loop on the far end of the layout and come back down Main Street toward the camera, the second block stops the Ford again until the Caddy is once more 3 feet behind. The Ford will again and again try to catch the Caddy but will never be permitted to.


The set up shown is a mess of patchcords and tools everywhere and looks a mess because I am testing this prototype set-up to what works and what spacing distance is best, moving sensors and such around to test different distances besides 36 inches set up in the in the video. Changing that distance requires disasembly of part of the road system and re-wiring . . . and I will be doing that next week as I explore details of how to "tune" this system best.
A natural question is "When one car is stopped by the system, any car behind it will catch up to very quickly - can this system really keep a bunch of cars all spaced apart?" A tentative answer is yes. I watched it control three, then four, and then five, keeping them all so none got closer than about a foot from another. But with cars that vary in speed as much as the Caddy and Ford do, that is the limit here. If I pick a set of cars that run much closer in speed, (I have a set of six that do) I can run six. I hope to tinker with the spacing and speed of the cars (inserting a diode in series with the motor will slow a car about 10 inches per lap) next week to to point I find a set of at least eight cars and a spacing that allows them to run continuously without getting closer than a foot to fifteen inches apart.
 

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Oh that is a slick engineering challenge for sure. I just love the idea of automated vehicles running on a layout.
It is going to be a real show stopper for all that see it in person, in action....when all cleaned up and running smoothly.
I can see the car in action as trains on the upper and lower tracks roll in oppisite directions, what a "IN ACTION" scene! I can hear the troublemaker in the back questioning why arent the people on the sidewalk moving?
Curious if you will add a stop light at the point you finally determine when the cars should stop and wait or you just might say they are picking up or dropping off a passenger?
It is going to be a very cool presentation, for sure.
 

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Discussion Starter · #4 ·
Curious if you will add a stop light at the point you finally determine when the cars should stop and wait or you just might say they are picking up or dropping off a passenger?
It is going to be a very cool presentation, for sure.
Yes, there will be stoplights, eventually. I alreayd have the MTH operating streeltlights and will build a relay system to coordinate them so they go through a red, yellow green cycle that is cooridnating with the starting and stopping of the cars.
 

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Yep. A traffic light or some reason to stop is needed since the control track is right out in the open. For my streets loop, I copied Lee’s IR setup and put the control section in an inconspicuous location. I was planning to add an MTH ITAD to stop cars at a stop sign. But I measured lap times for the cars that Lee gave me and the ones I bought or made and if I use cars that have nearly the same speed, I can run four with no tailgating even without the ITAD.
 

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Following intently.

For our public display, I want to get a street system operating. Wire-guided seemed best to me, but we run 3 hour intervals and I worried about that. Until the batteries get better, I'm not sold on wire-guided just yet. This seems like a great alternative thus far.
 

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Discussion Starter · #8 ·
This is a cool additional video, showing the system working to separate five cars that were initially all nose-to-tail. As the test posted on youtube with it explains, the system at present can handle up to eight cars and keep them nicely spaced. Nine begins to be a challenge for it.
 
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It would be really cool to have lights so they have an excuse to stop. Also, any way to have them slow down a little more naturally? Perhaps a supercap on the motor to give them a little coasting? Another idea is to simply reduce the voltage in the zone where they stop so they simply slow down to maintain spacing.

I have no idea how all these ideas fit into your scheme, and I'm also well away that...

Nothing is so easy as the job you imagine someone else doing! 😅
 

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Discussion Starter · #10 ·
It would be really cool to have lights so they have an excuse to stop. Also, any way to have them slow down a little more naturally? Perhaps a supercap on the motor to give them a little coasting? Another idea is to simply reduce the voltage in the zone where they stop so they simply slow down to maintain spacing.
The system has been designed to use the MTH traffic lights and I already have them. I just need to get these control blocks working well and installed permanently. Then my next step is get the traffic lights installed and to work in conjuncton with control blocks. I can actually use the present relays (controlloing the traffic) and their wiring to operate the red and green lights: just solder the MTH lights to the correct wires and I have red and green that alternate as they should. I think that with one additional relay I can get the yellow to come on in-between the green to red transition for about a second to a second and a half - but will have to try it to see if that works. Getting that yellow light to operate realistically - turn off the green =while turning on the yellow for a realistic 3 to 6 seconds before turning it off and the red on will requires a lot more [work, relays, sensors, testing]. I may try it that but frankly the one-second will probably do for me.

Slowing down the cars? They will go much slower, and normally will, at about 1/3 the speed you see in the videos (about 20-25 scale mph). I am running them here flat out at 16VDC with no PWM at all (max speed about 70 mph scale). I do all testing at these high speeds to make sure the sensors/relays can react fast enough; they have to switch power one and off in less time than a can move one inch and they operate in about half that time.

More realistic stopping? Yes, I have left room in all the cars for several supercaps so that eventually I can make the cars slow and start naturally. I've left that for the future though, I am not sure about several things: how much capacitance I need, how the supercaps would interact with/interfer with the PWM speed control, and how the supercaps would behave in a car fed power by a PWM motor controller. I intend to find out. So far one simple experiment showed me a stack of three 5.5VDC 1 F Cornell-Dubilier coin type supercaps in series across the motor will make one of these cars running flat out (16VDC with no PWM) start out in a very liesurely way and then run on after the power is cut, only gradually slowing for six feet!! So the idea seems to work and it seems that, roughly, three 5.5 VDC .25 F supercaps would be about the right amount, but what effect the PWM has on that, and vice versa, I still don't know.
 
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Wow Lee, I guess you've more than considered my observations, this is shaping up to be a really great addition to your layout! (y)

Hard to say how the supercaps will react to PWM, the charging may be different than with straight DC. I doubt the supercaps will affect the PWM itself much, especially the coin types. They have an ESR way higher than the beefier caps, and it's doubtful they'd have enough of a load to affect the PCM. The supercaps with the 100-200 mΩ ESR OTOH might make a dent in the PWM operation.
 

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Discussion Starter · #13 · (Edited)
I completed installing the wiring and the "power control station" for my operating Main Street. The photo below shows it in place. From left to right this is the re are two regulated power supplies, the leftmost set to 11.9VDC with a limit of .2amps current to provides power to all sensors and relays, and the right one set to 15.9VDC and limited to 4 amps which passes its power through two PWM (pulse width modulation) motor controllers (the two modules with the dials on top, to the right of the power supplies). One controls power sent to the straight Main Street section through downtown, the other power to the turn-around sections at the ends of the road loop.
It is all as orderly and literally screwed down as I could make it, and looks more of a mess than it is. Yes, there is a snakes' nest of wiring back there but I have a diagram/map and color code combination shuld I ever need to do work back there: there are a total of 58 wires or branches that I installed, all color coded. I use three sets of color coded super-flexible silcon stranded 20-gauge wire setting it up, and it took all the the weekend to get done. I highly recommend this wire for any similar projects. It is good quality and very easy to work with.
https://www.amazon.com/gp/product/B01LZ4CGXL/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
As completed the system works reliabily and as intended, keeping any six of the 26 vehicles I have built apart so they never get nose to tail even though they run at different speeds, and if I pick nine of the 26 that are closed to one another in speed, able to keep all nine separated by at least two car lengths as they cruise up and down the downtown Main Street at 22 scale mph.
Next part of the project is installing the parking lanes alongside the slot car track on each side of Main Street downtown, and then installing the traffic lights.
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This next photo shows a storage area I built for all the converted vehicles I have so far, to the right of the power station.
Electronic instrument Electrical wiring Audio equipment Computer hardware Gas
 
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