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I need a schematic... Answered

I need a schematic for a circuit using a 555 timer. I want a switch to activate the timer, which will provide 3 volts to a buzzer for one second, no matter how quickly the target is hit.

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jeff-o
jeff-o

11 years ago

Here you go!  All you have to do is plug in values until you get the result you want.

Monostable oscillator

You'll want to switch the buzzer using a transistor, since they can draw a lot of current.

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XOIIO
XOIIO

Answer 11 years ago

Thanks, but how exactly would I plug it in? I have literally no clue what I would need for the resistor and capacitor.

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jeff-o
jeff-o

Answer 11 years ago

Using that calculator, C1=330uF and R1 = 8.2k should get you close.  But be aware, the value of the capacitor can vary by as much as 20%, so your timer may not hit 3 seconds precisely (or in this case, exactly 2.9 seconds).  If it needs to be really close, include a 1k ohm potentiometer in series with R1 to "trim" the timing to a precise time period.

Also be aware that with this circuit, the timing will only start once the button is released.

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XOIIO
XOIIO

Answer 11 years ago

Thanks!

*Runs giddily to the electronics store*

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Goodhart
Goodhart

Answer 11 years ago

Um,  3 seconds?   I think he wanted a one second burst.
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jeff-o
jeff-o

Answer 11 years ago

Whoops!  I still had "3 volts" in my head.

Make that C1 = 100uF and R1 = 9100 ohms.

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Goodhart
Goodhart

Answer 11 years ago

that sounds a little better ;-)