Author Topic: 555 Timer question  (Read 1651 times)

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Offline stev.dk

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555 Timer question
« on: July 27, 2014, 03:32:51 pm »
Okay, so be prepared - anyone with an iq above 10 will be going  |O or :-DD within a few lines of this question, but im a at loss, and need some help here.

I have an alarm on my moped... so far so good. I want to make a red LED flash, like on cars, to show the alarm is active. I want it to blink for like 10ms and stay off for like 2 sec or something like that (didn't calculate the exact values yet). I'm using an astable configuration, with a diode going across R2, to get a lower duty cycle than 50%. Everything seems to be working BUT the led dosn't shut completely off, it dims to about 10% maybe. Why is this, and how to fix it? I tried using higher resistors, and running at 5v and not 12v, but it still dosn't turn off... I must be missing something.

I have it set up like this.

Crank it up till' everybody's ears are bleeding, then back off just a notch.
 

Offline rob77

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Re: 555 Timer question
« Reply #1 on: July 27, 2014, 03:35:00 pm »
where and how is your LED connected ?
 

Offline stev.dk

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Re: 555 Timer question
« Reply #2 on: July 27, 2014, 03:41:34 pm »
 :palm:

Its connected pin 3 --|>- resistor ---|> GND
Crank it up till' everybody's ears are bleeding, then back off just a notch.
 

Offline hamdi.tn

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Re: 555 Timer question
« Reply #3 on: July 27, 2014, 03:54:54 pm »
can you give the component value you used in you prototype ?
 

Offline stev.dk

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Re: 555 Timer question
« Reply #4 on: July 27, 2014, 04:15:05 pm »
Okay, i dont know what i did wrong... I took it apart and assembled again, and now it works as it should.

Same values... must have connected something up wrong... don't know what would cause the LED not to turn completely off... but assembled correctly, it works.  :-//
Crank it up till' everybody's ears are bleeding, then back off just a notch.
 

Offline hamdi.tn

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Re: 555 Timer question
« Reply #5 on: July 27, 2014, 04:20:56 pm »
 :-+ happen all the time  :P
 


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