[sdiy] LM13700 Oscillator Circuits and analog computers

[Ian Smith]

Thanks Scott. This is a great start. 

-Ian

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> Date: Fri, 4 Jul 2008 14:59:04 -0700
> From: music.maker at gte.net
> Subject: Re: [sdiy] LM13700 Oscillator Circuits and analog computers
> To: synth-diy at dropmix.xs4all.nl
> 
> Ian Smith  wrote:
>>
>>Hello all,
>>
>>I was advised to look at the application notes for the LM13700 
>>and I have a few questions. On the Triangular/Square-Wave VCO, 
>>would replacing Ra with a potentiometer allow the changing of the 
>>frequency ? 
> 
> I can help here: I built a _linear_ version of this oscillator, but the principle is the same for
> expo.  You would replace Ra with a current source, for expo, use an expo current source, for
> linear, use a linear current source.  Mine works very nicely in my FatMan which is why mine is linear.
> 
> Here is the schematic: http://home1.gte.net/res0658s/fatman/vcngvco.html (it's actually an LM13600
> in mine).  The top portion is the linear current source feeding pin 1 of the LM13600.
> 
> Someone else here likely already has an expo version of this that you can build.
> 
> ..
> 
> -- ScottG
> 
> -----------------------------------------------------------------
> 
> -- Scott Gravenhorst
> -- GateManPoly - FPGA Based Polyphonic MIDI LA/FM Synthesizer
> -- GateMan-III - FPGA Based Monophonic MIDI LA/FM Synthesizer
> -- PolyDaWG/8 - FPGA Based 8 Voice Polyphonic MIDI Synthesizer
> -- FatMan: home1.gte.net/res0658s/fatman/
> -- NonFatMan: home1.gte.net/res0658s/electronics/
> -- When the going gets tough, the tough use the command line.
> 
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