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Traffic lights

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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I'm not sure how traffic lights work in your part of the world, so I can't suggest anything more than generalities.

I would use another 555 oscillator to make the red LED flash. This could be controlled by the 4017 outputs to have the LED on, off, or flashing (which would be good if the red only flashes at one particular stage.

If the red always flashes, the simple solution is to get a red LED that flashes (some are available with inbuilt flashers)
 

Gregoraci Joseph

Dec 14, 2011
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I'm not sure how traffic lights work in your part of the world, so I can't suggest anything more than generalities.

I would use another 555 oscillator to make the red LED flash. This could be controlled by the 4017 outputs to have the LED on, off, or flashing (which would be good if the red only flashes at one particular stage.

If the red always flashes, the simple solution is to get a red LED that flashes (some are available with inbuilt flashers)

Steve,
Our lights are that when you push the switch you wait for the red light to appear, to be able to cross the road. For the drivers to know, that they need to stop to wait for them to pass, a pulse sound switches on as soon as the red light appear. In the circuit I had found and which I posted yesterday do not include a pulsing sound. I like to add only the buzzer pulsing while the red light is on, and not also the red led flashes. I wish someone would help me to introduce the buzzer with the circuit.

Thanks
 

CocaCola

Apr 7, 2012
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If you want to just add a 'buzzer' sound and no flashing, you can use a self contained 'buzzer' unit and simply replace the output to the red led in that circuit with a transistor and have that transistor drive the buzzer and red led... No time to draw it up but it's not all that hard, Google up how transistors work as a switch...
 

screwball

Jan 9, 2012
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You want to add another 555 for the buzzers pulse so pretty much the same circuit again, i quickly drew up what you want to add (add a resistor in series with the led)

rrgy.png


Not tested but should work
 

screwball

Jan 9, 2012
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Where the 5 goes?

Pin 5 on the 555 timer is the control voltage pin, you dont need to use pin 5 in the circuit, you may also notice pin 5 is not used on the original traffic circuit also (well it doesnt appear to be there)

Hope that helps :cool:
 

CocaCola

Apr 7, 2012
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The resistor you need to add goes here, the value is determined by your LED choice using Ohm's Law... The transistor is an NPN...
 

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Gregoraci Joseph

Dec 14, 2011
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screw ball,

This circuit i found it very helpful, but i want the correct type of the transistors you've drawn to be able to build the circuit correctly.

thanks a lot.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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BC547, 2N2222... In general it's going to work with almost any NPN transistor you can find.
 
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