I have a strobe light which has a xlr input for a 10v trigger. I want
to get this to flash in time to some music, I thought i could make a
cuircuit which would high pass a audio signal so i just get the hi
hats / cymbols and use this to switch a 10v charge. I dont have much
experience, so i need something simple or a schematic to follow. I
was also thinking about getting a pic like the arduino or pic16f84 and
writing a program to similar effect. Advice and help much appreciated
thanks
tim
How much experience is not much, and how complicated do you want to
make it? Digital signal processing is way overkill in my opinion -
but what are your needs? What do you expect to do and why? How good
does it need to be? Since you say XLR I assume your 're talking about
the microphone, stage, or professional musician's audio connector? Is
this for a multimillion dollar application or garage band?
Flash in time with some music . . . would imply the bass beat to me,
not the cymbals, since you have ride and crash cymbals as a rule - and
I doubt a simple filter could distinguish between a cymbal crash and a
rim shot.
Another reason to go for the bass drum - it is closer to a clean sine
wave where the cymbal is more like noise - a great many frequencies
together.
Just my two cents.
What you want to search for are schematics for high pass (cymbals) or
low pass (bass drum) filters. "The Op Amp Cookbook" would be good but
you should/may find something with Google. Microphone, pre amp,
filter, XLR connector.
A PIC for this is unduly complicated and wouldn't really add much -
you still need to detect the sound, amplify it, and filter it - the
PIC could filter it providing the clock is fast enough and your code
is slim enough - but a single op amp with a cap in the feedback will
do more for less effort. A pic may be easier to modify - but analog
active filters can be easily made tunable with variable resistors or
switching in different caps.
Basic concepts
http://en.wikipedia.org/wiki/High-pass_filter Stops low frequency
allows high frequency through
http://en.wikipedia.org/wiki/Low-pass_filter Opposite of high pass
http://en.wikipedia.org/wiki/Band-pass_filter Lets a specific
frequency through - tune it to one note
More advanced
http://en.wikipedia.org/wiki/Butterworth_filter more than you want to
know, but the Butterworth is commonly used for this type of function.
A real application
http://www.engr.uky.edu/~amdatt0/ Another guy doing things the hard
way using a switched capacitor filter using a single chip designed for
the purpose.
