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Topic: arduino bt small buzz & piezo knock sensors (Read 2 times) previous topic - next topic

Grumpy_Mike

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this might be better then


yep  :)

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do you mean that to get a lower gain i should add a resistor near c2

close ..... let C2 feed into a potential divider, the ratio of the divider will cut down the output of the amplifier.

kro

#11
Feb 03, 2010, 11:56 pm Last Edit: Feb 03, 2010, 11:57 pm by kro Reason: 1
ok i've been looking to potential divider in wikipedia





i think this would divide voltage output by 2
(gain x50 would be ok to me)

do you think i risk to burn arduino input or will it stop clipping at a max value ?

Grumpy_Mike

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i think this would divide voltage output by 2

Yes spot on.  :)

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will it stop clipping at a max value

It can't get get bigger than 5V because that is what the transistor is being fed with. So any larger output will simply just clip at 5V.

Now you will have no trouble with this because of the 100K series resistor, but when you have a capacitor coupled signal with one side of the capacitor going from 0 to 5V the other end of the capacitor can go from 5V to -5V. The 100K resistor will protect the arduino input but you might want to add some catcher diodes to the top and bottom rails, like here:-
http://www.thebox.myzen.co.uk/Tutorial/Protection.html

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