Hi
Im currently working on a traffic light project at university and would like some ideas/advice on how to go about doing it.
You can view the specification of the project from the following url :
http://coursemain.ee.ukzn.ac.za/enel3dah1/projects/3DA Project Specification 2007.pdf

My part of the design is "PART 4: The traffic lights" of the document.
Im thinking about using opto-isolator to seperate my part of the design and a triac to control the intensity of the lights. We are not allowed to use any programable logic devices .

Any suggestions would be appreciated.

 

Use an SSR to control the lights. Since the lights have to be run at reduced intensity at night you'll need a second SSR for each light that uses a circuit to reduce the intensity. It would be "If it's daylight use SSR1 and if it's night use SSR2+insensity reduction circuitry" SSR1 sends all the voltage to the lamp and SSR2 uses a resistor, diode, transformer, etc to send reduced power to the lamp.

If the SSR is a no-no then use a relay driven by a transistor. It's simple, cheap and you can go do something else. Be sure to put a reverse EMF diode across the coil.

There is nothing in there that says you can't have another higher DC supply such as 12V for running other circuits but you should be able to use the 5V line for SSRs and/or relays.

I also recommend looking up what a metal oxide varistor is and installing one of those at the proper rating in parallel with each lamp. The bulb life can be up to double with them depending on how dirty the AC power is. I also recommend them after the fuse and across the mains in your power supply for the same reasons.

If you really are masochist you could design a PWM circuit and a custom built SSR/relay circuit to control the light.

 

I was told to use an opto-isoltor/optocoupler to seperate the low voltage part of the circuit from the high voltage i.e the logic circuit from the traffic lights.
I also need to use a diac/triac to control the intensity of the bulbs and a timer.
Can anyone please provide me with a schematic of this since this is my first design course and im totally confused!!!

 

Isn't this more of a "can someone design my project for me because I'm on the wrong course" rather than a request for advice or assistance?

 

Blocco, please check post dates before making a reply. The college course in question ended more than a year ago.