[PD] (OT) safely connect piezo transducer to soundcard as microphone

[Martin Peach]

You could put a resistor in series to limit the current or a pair of 
diodes in parallel to clamp the voltage. Probably a pair of 1N4001s like 
this would work:

IN---+------+-----OUT
      |      |
      ^      v
      |      |
GND--+------+-----

Martin

On 2012-04-20 18:12, Matteo Sisti Sette wrote:
> Hi,
>
> This is OT but I'm sure many of you have used piezo microphones sometimes.
>
> I've often connected a piezo transducer to the microphone input of my
> computer (and other computers) by simply soldering the two wires to the
> T and S of a minijack plug, and it works just fine and my soundcard
> hasn't suffered any damage (apparently at least).
>
> However, I am concerned that a strong sound input (e.g. hitting the
> piezo transducer with with fair strength) may actually generate a
> voltage peak (thought only for a short time) capable of damaging the
> soundcard, couldn't it?
>
> Also, a friend of mine did the same with his Macbook and his headphones
> output has stopped working (may be just a coincidence though).
>
> Is there an easy way to make it safer? I seem to remember I had read
> somewhere (can't find it) about connecting a 1MOhm resistor in
> parallel... woudl that do the trick?
>
> thanks
> m.
>
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