[PD] Sensors

[Mathieu Bouchard]

On Fri, 31 Oct 2003, Marc Lavallée wrote:

> There's many ways to interface sensors. Using an audio card is definitely
> possible, but it's not a silver bullet. Many audio cards cannot be used
> an input interfaces, often because the input stages are expecting audio
> signals and nothing else.

BTW, if you have electric signals that are of very low frequencies not
easily dealt with using audio cards, or maybe even signals that don't have
frequencies per se, then you may modulate those using a high frequency
wave, and then analyse the resulting signal in software to find out its
volume. I have successfully used that to pick up the signal from a
photosensor, through an old audio card, and into a Ruby script, a few
years ago. This should be easy to do. I used a 555 back then, but I guess
it can be done using about 2 capacitors and 3 transistors, if I'm not
completely incompetent wrt electronics.

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Mathieu Bouchard                       http://artengine.ca/matju