f/v converter & log circ
pfperry at melbpc.org.au
Sat Jun 7 04:41:29 CEST 1997
At 11:35 PM 6/06/97 +-200, Jonas Karlsson wrote:
>I am thinking about building a frequency to voltage converter and use it to
control the synthesizer i'm building. The f/v converter should use a
squarewave (from my D110) at the input and create one voltage that is
proportional to the frequency, and one that is proportional to the amplitude.
>Is this a good idea? This way I don't have to build (or buy) a MIDI to CV
>The v/f part is easy to design, but the problem with it is that the output
of it is exponential, so I have to build an exp. to lin. converter. Is there
an easy way to do this?
>I really would appreciate any comments and ideas on this subject.
the answer to this, and almost every other purely analog electronic question
ever asked in this list, is to be found in "the Art of Electronics" vol 2
Horowitz & Hill
Cambridge University Press(available many languages)
in this case the log convertors are on p254 and p255
they are based on the - not cheap- LM394 supermatched npn pair but if you
are experimentally inclined i think the CA3046 transistor array should do -
used before in this type of thing
Winfield Hill one of the authors often replies in newsgroup
have a look via DejaNews newsreader
i once lost a sale for my midi-cv unit (which as a standard feature puts out a
voltage directly prop to frequency of input midi note) when i showed that the
MS20 could in fact look at the output from any midi module & generate a CV
by itself...... so if you have a MS or Yam CS series synth all you need is
the F to V..
Paul Perry mfg Frostwave MIDI-CV convertor
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