Hi, new here and to the world of electronic design.

I have made a circuit that will bring on the signal lights of my bike at a reduced voltage for running lights. I used a 555 timer as a PWM. It all works as intended except that I would like it to shut off when the signal lights are on. Also I would like it to stay off for a period of 700ms and then resume operation. the entire circuit is on the hi side of the sig. light so there is no ground signal on the board. Any thoughts of how this could be done would be apreciated.

Thanks
Earl

PS; I am trying to keep this as simple as possiple, I would like to utalize the 12v back feed that will be present when the sig. light is flashing as the trig. to shut down the timer. I would also like it to remain off for the full period of the cycle of the sig. lights, 680ms(340ms on, 340ms off)

Can I trig pin 2 hi and then let it go low through a RC circuit ?

Attached Images

circuit diagram.jpg (229.3 KB, 21 views)

 

Please provide a schematic.

You can take pin 4 low, if it's an astable but without a chematic it's difficult to know.

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Do you have a schematic (Diagram) that we can look at?

 

Whoops, must have sent at same time.

 

Ill try to post the diag. Also I would like to use the 12v feedback from the sig. lights to shut off the timer.

Also note that the fet on the diag. is wrong, its not a dual gate, but this was the only thing close that I had the time to find.

Attached Images

circuit diagram.jpg (229.3 KB, 35 views)

 

Just connecting pin 4 to +V via a pull-up resister and connecting it to 0V when youy want to turn it off should do the job.

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Yes that would work, but I do not have a ground, and I would like to utilize the hi sig. from the sig. light as the trigger. I am a n00b when it comes to this stuff, so a detaled description or diagram would be usefull

Thanks
Earl

 

You will have ground on pin 1 of the 555, if you pull pin 4 high with a resistor like Hero999 suggested a transistor between pin 4 and pin 1 should work if I am understanding you correctly.
Use the high signal from the signal light to trigger the transistor.

 

Alright then, do it the other way round, tie pin 4 to pin 1 with a pull down resistor then connect it to +V when you want to turn it on.

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