[Noisebridge-discuss] seeking circuit idea: frequency to voltage

[jim]

off the top of or out of my whatever... 

   within a portion of the audio range, sending 
a signal through a capacitor will have a rolloff 
such that higher frequencies pass more easily 
through the cap. essentially there'd be more 
power transmitted at higher frequencies, possibly 
measurable as higher voltage: you might rectify 
it or capture peaks or some such and drive the 
display from that part of the circuit. 
   for greater range, add more caps in parallel, 
each cap having a different value. 

   i've read that the way to get responses is 
not by asking for people to reply but rather by 
putting out incorrect information. i'm here to 
help. 




On Thu, 2009-12-10 at 20:55 -0800, Michael Shiloh wrote:
> a student wants to build a bar graph type display that will show 
> frequency, not voltage. the frequency is in the audio range.
> 
> i know there are chips to do this, but i'd like to find a circuit using 
> more basic and common components, like a 555, 741, 2n2222, etc.
> 
> precision and linearity is not an issue. it's merely a visual element.
> 
> any ideas?
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