SV: RE: [sdiy] PAIA VCO, LM13700 diode temp comp.

[karl dalen]

Thanks for that diy report Phillip, most valuable!

KD

--- phillip m gallo <philgallo at attglobal.net> skrev:

> Karl,
> 
> After decades of staring at the National "app note" and wondering what it's
> result would be, PAIA's publishing of their VCO implementation based upon
> the technique finally caused me to break down and try the approach.
> 
> I built a pair of VCO's based upon the PAIA scheme for the sawtooth core
> (but used different wave shapers).  As Jim points out the Gm of the OTA is
> what temp. compensates the core.  My variance from the PAIA implementation
> was;
> 
> 1)using a REF-02 for expo, comparator and waveshaper references.
> 2)used MAT-03's for the expo pair,
> 3)used an AD823 for the integrator buffer on one VCO and a LF412 for the
> alternate.
> 4)implemented a POT for the Hi-Fz tracking adjustment.
> 5)"leveled" the MAT03's to the height of the socketed '13700 so they could
> share a piece of aluminum as a common radiator.
> 6)As is my general practice i used 1% and 2% film resistors (for what that's
> worth).
> 
> I implemented the VCO's on perf board so i could wire separate ground star
> networks for the AC and DC circuit components (meeting at supply input).
> Given the parts, you can build the core in an evening to analyze your
> impression of the circuit.
> 
> I was quite pleased and testing exhibited better results than that reported
> by Ian but one set of test i didn't do was swap a variety of '13700's into
> place to note their effect.  Both VCO's did perform similarly.  The VCO's
> and notes from testing are still in storage although i moved nearly a year
> ago (those who've visited my garage understand).  I'll be digging the VCO's
> out of storage for project reasons in a few weeks and re-run the tests if
> you're interested.
> 
> regards,
> p
> 
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of karl dalen
> Sent: Monday, October 17, 2005 4:42 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] PAIA VCO, LM13700 diode temp comp.
> 
> 
> Long time ago there was discussions on the PAIA
> VCO temp drift compensation using the diodes of
> the LM13700, how did that turned out?
> 
> Was it a good idea of temp compensation?
> 
> REG
> KD
> 
> 
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