(4)Switches + (8)LEDs + (2)Power Sources + (1) Mile = CHALLENGING!

Thread Starter

icom918

Joined Jan 19, 2018
11
Hello,
I'm in need of expertise with wiring a "Stop/Go" Light on a mountain.
Driving up, or down, an 8' winding road w/o knowing if someone is coming up as you're going down, or down when you're going up.

Using (1)Switch & (2)Red & Green LEDs per NEMA Box on each side of the road. (2) at the top of the mountain & (2) at the bottom.
The driver would press the button on the box to their left (going up the mountain) & the Green LED in the box you press, as well as the box on the other side of the road illuminate. The boxes on both sides of the road at the top of the mountain LEDs turn Red.
When you get to the top, the driver presses the button on the top of the mountain, on the drivers side box, and the lights turn off.
When driving down, the driver would press the button on the other side of the road, again on their left (driver's side), and it turns the Green LEDs on the (2)boxes up top, and the Red LEDs on the (2)boxes at the bottom.
Once down at the bottom, again the driver would press the button on their side, and all the LEDs turn off, waiting for the next press, whether it be someone coming down, or someone going up.

I would like to use a Red & Green 10mm Super-Bright LEDs at the bottom & top of the mountain. (Kind of like a stop light)
LED specs:
  • 625-630nm Red
  • 2.1-2.3VDC Forward Voltage
  • 80mA Forward Current
  • 30 degree viewing angle
  • 10,000-12,000 MCD output
The power source would be a 12VDC 680CA AGM Vehicle Battery w/ 1W Solar Charger aprox. 20' from the top boxes (hidden & locked of course). I could put (1) or multiple batteries at the bottom of the mountain, or a Battery at the top & a battery at the bottom.
I was thinking that if I used (1)Battery at the top & (1)Battery at the bottom, I could use small gauge wiring to connect the top w/ the bottom (like signal wiring). Even at 2AWG, at 1 mile the loss is ~2.1VDC. If I need to run #2 up there and back, not only is that very expensive, but also a lot of loss per run.

I hope I explained it well enough.
Any help is greatly appreciated.
Thank you in advance!
 

ElectricSpidey

Joined Dec 2, 2017
1,802
What happens if somebody is driving behind you, and enters the mountain pass after you have turned on the lights, and ends up on the road between the two points after the first driver reaches the bottom/top and turns off the lights?

Shouldn’t you turn on red at both points so there is never more than 1 car taking the pass at the same time?

Because I would assume green means go.
 

LesJones

Joined Jan 8, 2017
3,497
How sould it behave if the driver exiting the section of road forgets to press the button ? Should there also be a timer for this situation ?
Would there be line of site between the top and bottom of the section of road to allow the use of a UHF radio link instead of wire ?

Les.
 

Thread Starter

icom918

Joined Jan 19, 2018
11
Thank you both for your time & responses.
At any time, there could be 1 vehicle or 6 going up or down. I figured the first person up presses the button to turn on & everyone behind knows it’s safe to go up. Last person turns it off.
No line of sight. RF isn’t an option.
 

Thread Starter

icom918

Joined Jan 19, 2018
11
I thought about that, but I’d need a timer.
Different vehicles go up there; (2)Axels, (3)Axels, Trucks w/ Trailer, etc.
I told everyone this would be challenging. Haha
 

WBahn

Joined Mar 31, 2012
26,398
Thank you both for your time & responses.
At any time, there could be 1 vehicle or 6 going up or down. I figured the first person up presses the button to turn on & everyone behind knows it’s safe to go up. Last person turns it off.
No line of sight. RF isn’t an option.
How does the last person know, for sure, that they are the last person? The scenario that could easily lead to this has already been mentioned. Tom gets to the bottom of the mountain and all of the LEDs are off, indicating that no on is on the road. He activates the system and the lights at the bottom turn green and he heads up. Halfway up, Dick gets to the bottom of the mountain and the lights are green, so he heads up. Tom gets to the top. Since he isn't aware of Dick, he hits the button to turn all the lights off. Sue then wants to come down and sees the lights off and so she hits the button to turn the top lights green and heads down, only to run head on into Dick.

Any system that relies on humans to remember to do something that they don't absolutely have to do, is likely doomed from the outset. Further, it really CAN be worse than nothing at all. If Dick and Sue both trust the system, they believe that no one is coming the other way and so they don't drive like they expect to meet oncoming traffic at any moment. Without the system, the KNOW that this is a possibility and drive accordingly.

As for needing a timer -- if you have the power to run the LEDs, then you have the power to run the timer. You just use a microcontroller to control everything. About the only thing you need to worry about there is the temperature extremes and whether the components can handle it, but unless you live someplace really extreme, that just comes down to proper component selection. Plus, if it's too cold/hot for properly chosen electronics in your system to work, then the electronics in the cars themselves are in trouble.
 

Thread Starter

icom918

Joined Jan 19, 2018
11
Hi. Ok.
I live in the desert, so it gets to 120 ambient. Inside the box would easily reach 180+ temps.
Lowest temps are around 20 degrees.
That’s why I was looking for a simple LED/Switch setup.

To use a pressure switch system still would not work with a timer since some drive slow & some drive faster, causing either premature clear, or prolonged waiting. What if they get a flat & have to change their tire 1/2 way up.
What about a counter?
Each person presses the button?
Example: Tom heads up, he’s almost to the top, Joe at the bottom sees it’s still green, presses the button & heads up. (2)presses, the top would wait for (2)presses to clear.
I’m sure that would need an IC chip, but maybe it would still be simple enough to stay cool & not be affected by the high temps?
 

AnalogKid

Joined Aug 1, 2013
9,353
How. Long. Is. The. Road.? This governs everything.

A single LED with a 30 degree beam width is too small and too narrow to be un-missable by all sizes and shapes of vehicles. Used LED traffic light "bulbs" are available cheap on ebay. If you don't want to deal with that much power, consider smaller daylight-visible arrays.

If the road is long and twisty, the only way to reliably manage the two-car problem is with a counter.

A fundamental requirement of the system is that *everyone* remembers to push the clear button at the end of the road. How often will that not happen, and how is the system reset?

Temperature is not an issue. 120F is less than 50C. Most commercial grade chips are rated for 70C; industrial to 85C; MIL to 125C

ak
 

Thread Starter

icom918

Joined Jan 19, 2018
11
The road is very close to a mile long. It is about a 12 degree grade, narrow & winding.

Good to know temperature isn’t a factor. Finances, on the other hand will be a factor.

Good to know a counter would work. Do you think it would work, at a mile of wire, with all of that voltage loss?
Could it be powered at each location (12v battery at top & 12v battery at bottom) and just use small gauge signaling wire?
5000’ of wire isn’t cheap.

I haven’t done electronics in over 16 years. Would you be able to make a schematic for me?
I’ll bread board it 1st to make sure I build it correctly, then I can build it on PCBs.

Thank you!

How. Long. Is. The. Road.? This governs everything.

A single LED with a 30 degree beam width is too small and too narrow to be un-missable by all sizes and shapes of vehicles. Used LED traffic light "bulbs" are available cheap on ebay. If you don't want to deal with that much power, consider smaller daylight-visible arrays.

If the road is long and twisty, the only way to reliably manage the two-car problem is with a counter.

A fundamental requirement of the system is that *everyone* remembers to push the clear button at the end of the road. How often will that not happen, and how is the system reset?

Temperature is not an issue. 120F is less than 50C. Most commercial grade chips are rated for 70C; industrial to 85C; MIL to 125C

ak
Voltage would be an issue, to power multiple LEDs. I was going to Silicone a Diffuser Sheet on the front of the box. 20,000mcd should be visible that way, right?

I replied to your questions in the thread. Not sure if I did that right.
 
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AnalogKid

Joined Aug 1, 2013
9,353
I missed the road length in the thread title; my bad.

One power source is convenient and makes for less installation, but I think two power systems and running signal-only wiring is the way to go. The standard design limit for telephone wire from the central office to a home is 18,000 feet, so I laugh at the dinkiness of your 5000 feet. You'll need transient protection on both ends because you are building a 5000 foot long lightning receiver.

What is your power budget:
Solar/battery output voltage
LED voltage/current/power on each end
Longest operate time
Shortest recharge time
Longest time between charging periods

I thought the easiest to install and maintain would be to put all of the brains at one end, and have the other end be nothing more than the switches and displays. BUT it looks like two LED colors and two switches at each end, and that is a bit much to encode into only two wires. Still thinking on that.

It seems to me that whenever the LEDs are on, the two ends always are the opposite colors. If that is true, it reduces the logic but requires a third state with both LEDs? Is that your plan, or do you have another operating sequence in mind?

I get that the wire will be expensive, but how many wires do you think you can afford? More wires = less circuit stuff.

This problem could be considered a variation of an elevator car controller problem, a semi-classic microcontroller design puzzle for beginners. Therefore, at some point words like PIC and Arduino will start flying around this thread. R.E.S.I.S.T.

ak
 

LesJones

Joined Jan 8, 2017
3,497
If you have a battery and solar cell at each end the wire would not have to carry a significant current. It would just send messages between the two ends My initial thought is an RS232 link witch would require 3 conductors. With slightly more complex electronics it could be done with two conductors. I was thinking of something like 4 core telephone cable. Choice of cable would depend on weather it is to be buried in the ground or run on poles. My initial thought on the electronics was a small microcontroller at each end but if you have not done any electronics for a long time then you would probably not be able to program the microcontrollers. It could be done without microcontrollers but it would require many more components.

Les.
 

Thread Starter

icom918

Joined Jan 19, 2018
11
I missed the road length in the thread title; my bad.

One power source is convenient and makes for less installation, but I think two power systems and running signal-only wiring is the way to go. The standard design limit for telephone wire from the central office to a home is 18,000 feet, so I laugh at the dinkiness of your 5000 feet. You'll need transient protection on both ends because you are building a 5000 foot long lightning receiver.

What is your power budget:
Solar/battery output voltage
LED voltage/current/power on each end
Longest operate time
Shortest recharge time
Longest time between charging periods

I thought the easiest to install and maintain would be to put all of the brains at one end, and have the other end be nothing more than the switches and displays. BUT it looks like two LED colors and two switches at each end, and that is a bit much to encode into only two wires. Still thinking on that.

It seems to me that whenever the LEDs are on, the two ends always are the opposite colors. If that is true, it reduces the logic but requires a third state with both LEDs? Is that your plan, or do you have another operating sequence in mind?

I get that the wire will be expensive, but how many wires do you think you can afford? More wires = less circuit stuff.

This problem could be considered a variation of an elevator car controller problem, a semi-classic microcontroller design puzzle for beginners. Therefore, at some point words like PIC and Arduino will start flying around this thread. R.E.S.I.S.T.

ak
Yes, the colors would be opposite, so press & yours turn green & the other end turns red. Once at the other end, depending on the number of times pressed, that end will need to be pressed that amount of times. Once completed, the LEDs turn off & await being pressed again, on either end.
There probably would have to be a fail safe timer, but if someone gets stuck on the road, I don’t want people heading up, or down, while a vehicle has a flat or something.
(1)12V car battery at both ends w/ 1W Solar charger to keep charged during the day & just battery at night. That would mean ~13.6V daytime & ~12.2V nighttime.
I could use 12-pair comm cable, but that’s only 24AWG Solid.
Ideas?

&&&& Thanks for your help!!

If you have a battery and solar cell at each end the wire would not have to carry a significant current. It would just send messages between the two ends My initial thought is an RS232 link witch would require 3 conductors. With slightly more complex electronics it could be done with two conductors. I was thinking of something like 4 core telephone cable. Choice of cable would depend on weather it is to be buried in the ground or run on poles. My initial thought on the electronics was a small microcontroller at each end but if you have not done any electronics for a long time then you would probably not be able to program the microcontrollers. It could be done without microcontrollers but it would require many more components.

Les.
That is doable.
Programming would not be easy though. I was hoping for a simple solution.
I know nothing about microcontrollers. It sounds complicated. I’ll need fail-safe solution.
You all are coming up with great ideas.
I just would need schematics to try it on a breadboard 1st
 
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AnalogKid

Joined Aug 1, 2013
9,353
12 pair seems expensive unless you just happen to have a cheap source for it, but it would be more than enough to run signals and power.

The system reduces to a single up/down counter, one direction flipflop, one lights on/off flipflop:

Two enter buttons OR-ed into the up clock
One enter button sets the direction ff
Counter change-to-one sets the on/off ff
Two exit buttons OR-ed into the down clock
Counter return-to-zero resets both ff

Wrapped around this are the electronics to get things in/out of the remote station.

ak
 

Thread Starter

icom918

Joined Jan 19, 2018
11
12 pair seems expensive unless you just happen to have a cheap source for it, but it would be more than enough to run signals and power.

The system reduces to a single up/down counter, one direction flipflop, one lights on/off flipflop:

Two enter buttons OR-ed into the up clock
One enter button sets the direction ff
Counter change-to-one sets the on/off ff
Two exit buttons OR-ed into the down clock
Counter return-to-zero resets both ff

Wrapped around this are the electronics to get things in/out of the remote station.

ak
I’m kind of lost. Sorry. It has been awhile.
Do you mean (2)JK Flipflops 555?
 

AnalogKid

Joined Aug 1, 2013
9,353
No 555's expressed or implied, although I almost made a snotty comment about them earlier.

Two flipflops, probably Set-Reset or D, to be determined later. Look into the CD4013. It is two independent D ff's with direct set and reset inputs, so it can do several things.

Separate from that, think about the next layer of control logic. If someone is coming up the hill, do you want the system to lock out any down-hill button presses? If so, it changes the logic a little but I think it still might fit into one counter and two ff's with a couple of added gates.

ak
 

Thread Starter

icom918

Joined Jan 19, 2018
11
No 555's expressed or implied, although I almost made a snotty comment about them earlier.

Two flipflops, probably Set-Reset or D, to be determined later. Look into the CD4013. It is two independent D ff's with direct set and reset inputs, so it can do several things.

Separate from that, think about the next layer of control logic. If someone is coming up the hill, do you want the system to lock out any down-hill button presses? If so, it changes the logic a little but I think it still might fit into one counter and two ff's with a couple of added gates.

ak
Lockout - I don’t think would be necessary. If they see red, they won’t press it until the last person up presses the button to clear the LEDs. It would be nice to ensure an accidental press doesn’t cause any issues with the circuitry though.

Would a counter need a visual indicator (segment LED) to show number of presses at bottom & presses at top?
Example: 1st person presses, number 1 displays at top & bottom. 1/2 way up, number 2 displays to indicate 2 people are headed up. Once 1st person gets to top & presses button, number 1 displays, then last person presses & clears LEDs & numbers clear?
 

BobaMosfet

Joined Jul 1, 2009
1,850
Much better way to do this, using inductive coils and micro-controllers. Not all that expensive either. Completely autonomous. No button presses, and algorithmic logic can compensate for any situation.

[edit] I've removed my GSM & FO remark-- I was in error on power-requirements, (my mind was trying to solve a tangential issue that was less of a concern, in the end) and I'm fairly certain that a copper run will be even more cost effective than GSM. Thanks AK.

Light options:

RED means stop,
GREEN means go,
YELLOW means caution/slow.

MCUs can determine vehicle counts, direction of travel when clear, when not, how to avoid a head-on in some situations, and how to alert both drivers if simultaneously heading towards one another before they meet. All relatively straightforward.
 
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