Four way UK traffic lights

[Dean081]

I am trying to build a set of traffic lights for a crossroads junction. This is the circuit I am using, below I have two working circuits one for each pair. I am struggling to find a way to trigger the circuits to operate opposite to each other, so they sequence as real lights do. Any help appreciated. Thanks.
http://rookieelectronics.com/sequential-traffic-lights/

 

[(*steve*)]

You only need a single 555 and 4017.

I would also recommend a slightly higher power supply voltage and series resistors for the green led.

What you then need to do is to decode the outputs in 2 ways appropriate for each direction of travel

Something like

1. Red. Red
2. Red green
3. Red green
4. Red green
5 red amber
6. Red. Red
7. Green. Red
8. Green red
9. Green red
10. Amber red

 

[Bluejets]

http://www.555-timer-circuits.com/traffic-lights-4-way.html

 

[(*steve*)]

Of course it all depends on how your traffic lights are sequenced.

That circuit doesn't mimic the sequence used here. Maybe the UK??

 

[duke37]

I made a traffic light driver using a 4017 and fets to drive a full sized light to train children. A 4017 can give 10 time periods but with a simple oscillator these will be all the same.

In the UK the sequence is
red
red and amber
green
amber
red

For a two way layout there will be a time with both ways are on red. For a four way system, things will be even more complicated usually with green arrows. In this case, a micro would seem to be the way to go but is not my scene.

 

[AnalogKid]

The schematic in post #1 is a mess. The one in post #3 is much better. Note that a 4017 output is rated for only 4 mA, and will have significant output voltage sag at that level. Better to diode-OR the outputs into a small MOSFET like a 2N7000, switching the LEDs to GND.

ak