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Police Lights Circuit - Help?

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3lectrix

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I'm trying to build a circuit which I am doing on a breadboard and using a 9v battery to power it.

police-lights.gif

When the circuit is built and I plug in the battery the two LEDs on the right hand site light up and stay lit.

Could there be a problem with the transistor not getting enough voltage from the base?

The simulation runs without any problems.
 
Sometimes the 555 will fail to oscillate in astable mode when pin 5 is left open. Try putting a 10nF capacitor from pin 5 of the 555 to ground.
 
hi,
When reset the 4017, the '0' output is High, so the right side transistor is ON.

Also dont leave the 4017, RESET pin floating.
 
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And also, normally, R1 and R3 should be connected to pin 7 of the 555 (discharge). Pin 3, which is the output of the 555, should be the only signal connected to the IC2 CLK input.
 
And also, normally, R1 and R3 should be connected to pin 7 of the 555 (discharge). Pin 3, which is the output of the 555, should be the only signal connected to the IC2 CLK input.

hi,
The 555 will oscillate in that circuit, the output is connected back thru a resistor to the timing cap.
 
Another consideration for your circuit not related to the timer or counter function. Assuming the LEDs are blue and red, the resistances of R4-R7 will need to be adjusted for balanced current and/or brightness.
 
Hi 3lectrix,

So to summarize, the main problem with the circuit will be solved as follows:

1) Untie the R1 and R3 resistors from pin 3 of the 555 and put them back to pin 7 where they belong !:D
2) As ericgibbs mentioned, minimally tie the 4017 Reset pin to ground.

That should get your circuit running !
 
wow, great information! It works!

I attached the resistors to pin 7 and also grounded reset. works perfect!
 
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