2 traffic lights become one project help required...

[viking11]

Hi all,

I have two systems that each have their own traffic lights (red/Green lights). However, using two traffic lights is not OK and therefore need to combine the outputs from each system into a a controller of some kind that provides an output to a single traffic light.

Requirement:
Only once both systems give a green status/output may the traffic light turn green, all other times the traffic light is to remain RED.

i.e.
i)
SYSTEM 1 GREEN
SYSTEM 2 RED
TRAFFIC LIGHT - RED

ii)
SYSTEM 1 RED
SYSTEM 2 RED
TRAFFIC LIGHT - RED

iii)
SYSTEM 1 RED
SYSTEM 2 GREEN
TRAFFIC LIGHT - RED

iv)
SYSTEM 1 GREEN
SYSTEM 2 GREEN
TRAFFIC LIGHT - GREEN


INPUT and OUTPUT information:

Signal from system 1:
3 wires (red light, green light & common)
12V DC (flashing)

Signal from system 2:
3 wires (red light, green light & common)
110V AC (Solid)

Output to the traffic light:
3 wires (red light, green light & common)
110 AC (Solid)

Anyone that can help and provide a diagram/description of how this can be achieved it would be much appreciated!

Thanks,

A mechanical engineer that has no electrical knowledge whatsoever!

 

[itsmoked]

It depends on the design of the equipment. You need to logically AND the two signal light greens together. How that's done would defined by the equipment.

You also may have to deal with the flashing aspect of the green that flashes - or maybe not depending on the equipment.

Usually traffic signal lights are controlled by heavily certified electronics that have specific inputs and outputs.

Are you just winging it?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MacGyverS2000]

This sounds like a lab project problem for school...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[viking11]

In terms of equipment, we cannot touch any of the internals from either control boxes, we can only use the outputs to avoid affecting warranty issues etc...

Its a little bit of winging but the systems we are using a for simple control systems - nothing regulated per se.

Know any students that would want to put something together for us then MacGyver?

 

[IRstuff]

Pretty much any EE senior in college should be able to rough out what you need.

TTFN

FAQ731-376

 

[MacGyverS2000]

viking,

Take it to the local university or tech school... students get "real world" experience they can put on their resume, you get a solution for dirt cheap. Everybody wins, and I wish more companies offered such experience to upcoming grads...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[jake3533]

What you need to do is make an interface circuit with a J&K flip flop that will toggle and flip both outputs when the systems are both green and connect that to an And gate and use a standard micro-controller that you can program the states in the great thing about the J&K flip flop is it only changes when both outputs are high and it will not care about the flashing lights on the DC module you also need to interface the dc voltage on the ac voltage by creating a diode bridge or rectifier-circuit as you have both dc and ac

 

[VEBill]

Reading between the lines, this project has nothing to do with 'traffic signals' (outdoors, cars and trucks, beep-beep). It's simply two systems that provide status (red/green). Right?

If you could reuse the System 1 status lights, and could accept the flashing, then the solution might be very simple: use a 120Vac relay controlled by System 2 Red to redirect System 1 outputs to the Red light.

In other words, System 2's Red signal would force System 1 to flash its red bulb (no matter what).

One relay, maybe a diode or two.

A complete solution would perhaps include consideration of failure modes. It depends on the safety im

 

[VEBill]

...plications.

(Unintentional post break, but a bit funny given the topic of the sentence.)

 

[waross]

This really sounds like a school project with artificial constraints to direct the solution in the direction that the instructor wants to go.
When a controller goes to green status, the amber and red are off. So when a signal goes to green, amber and red will be off until the other controller is green.
Usually not acceptable in the real world.
With no information regarding the controllers, an attempt at solution is almost futile.
A complete solution will probably require a PLC. A simpler, easier solution may be to just use a PLC and lose the existing controllers.
Sure sounds like class work when you don't want to tell us the application.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[VEBill]

My guess:

Sometimes called 'tower lights', almost (but not quite) as confusing a name as 'traffic signals'. Used in factories to indicate go/nogo status of a machine. Perhaps his boss wants him to combine the status of two machines.

 

[elechydro]

You simply need two relays. First the power for the red light will be connected to the n/c contacts of the relay 1. The green signal coming from the first maching will run into the n/o contacts of relay two. the green signal from the second machine will energize relay two sending power to both the green light and relay 1 energizing it, switching the contacts and disrupting power for the red light. with this setup both "green" signals will be required from the machines in order to turn the red light off and energize the green light. this setup will be cheaper than any plc and probably easier to wire and no programming involved!

 

[elechydro]

oh sorry, after i wrote that i re-read the prior notes and i should clarify. i suppose the flashing green would sorta throw that system for a loop! did you figure this out or no?

 

[viking11]

Many thanks all. I finally managed to solve the problem with the help of you all. I'll post the full solution soon.