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Traffic Lights
10 years 3 months ago - 10 years 3 months ago #17449
by stonysmith
Traffic Lights was created by stonysmith
The subject has come up a few times of adding Traffic Lights to the streets your layout.
I was messing around with the idea.. there are many small (micro) computers that can do the job, but I also wanted the minimum number of wires possible.
I came up with this:
With just four wires (and twelve LEDs) you can have a four-way stop intersection that is fully automated. With this, you could have a number of intersections all on the same pattern of lights, and depending upon how many pins you have on your microcontroller, you could have several different zones of lights that are timed differently.
I'm still looking for how to get some SMD and a micro-circuit board for each hanging signal, but at least I now have a working arrangement that only requires four wires.
I was messing around with the idea.. there are many small (micro) computers that can do the job, but I also wanted the minimum number of wires possible.
I came up with this:
With just four wires (and twelve LEDs) you can have a four-way stop intersection that is fully automated. With this, you could have a number of intersections all on the same pattern of lights, and depending upon how many pins you have on your microcontroller, you could have several different zones of lights that are timed differently.
I'm still looking for how to get some SMD and a micro-circuit board for each hanging signal, but at least I now have a working arrangement that only requires four wires.
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10 years 3 months ago #17452
by markm
Replied by markm on topic Traffic Lights
Stony,
I have a little more time now than for my earlier post. If you're willing to buy about 500K signal heads, I'm sure Dialight would consider it
I've played with the idea of Z scale traffic signals for some time and can give you some thoughts.
Your logic table is essentially correct for a mechanical traffic signal priorr to about 1970. After that those big controller boxes contained an 8008 microcontroller system. At that time a RED-RED state before then next GREEN-RED became common for the signals. You can still do this state by applying complementary pulse streams to lines 1 & 2 and matching pulses on 0 & 3 to keep the greens off.
For building the signal heads, I was planning to use a backlight shield from a single layer of FR4 PCB material with a single layer of copper. This is commonly known as flex PCB. I'd suggest using white LEDs and use color filters: the LEDs are cheaper by the dozens and you won't have to flight the forward voltage differences between the colors.
I built a controller using a 556 timer chip and a 22V10 GAL. It included a train crossing trigger to change the light and signals for the crossing lights. Also could be daisy-chained to stagger the timing for multiple traffic signals.
Hopes this helps,
Mark
I have a little more time now than for my earlier post. If you're willing to buy about 500K signal heads, I'm sure Dialight would consider it
I've played with the idea of Z scale traffic signals for some time and can give you some thoughts.
Your logic table is essentially correct for a mechanical traffic signal priorr to about 1970. After that those big controller boxes contained an 8008 microcontroller system. At that time a RED-RED state before then next GREEN-RED became common for the signals. You can still do this state by applying complementary pulse streams to lines 1 & 2 and matching pulses on 0 & 3 to keep the greens off.
For building the signal heads, I was planning to use a backlight shield from a single layer of FR4 PCB material with a single layer of copper. This is commonly known as flex PCB. I'd suggest using white LEDs and use color filters: the LEDs are cheaper by the dozens and you won't have to flight the forward voltage differences between the colors.
I built a controller using a 556 timer chip and a 22V10 GAL. It included a train crossing trigger to change the light and signals for the crossing lights. Also could be daisy-chained to stagger the timing for multiple traffic signals.
Hopes this helps,
Mark
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