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The calibration can be found here:
http://www.jhaible.com/living_vcos/jh_living_vcos.html
TRI to SIN converter:
source: http://www.muffwiggler.com/forum/viewtopic.php?t=24267&start=0&sid=447cefb9a3fd208a3ab9f7c9245122b3
It is a precision rectifier and double-and-lift circuit to convert saw to triangle, followed by a standard differential pair sine shaper (from the Thomas Henry VCO-1, but optimized for Euro rails). Here's the parts list:
1 quad opamp (TL074)
2 NPN transistors (2N3904)
2 small signal diodes (1N914 or 1N4148)
3 22p ceramic caps
1 20k trimmer
1 50k trimmer
1 100k trimmer
and a small pile of 1/4W standard resistors:
1 390R
1 1k
2 2.2k
6 10k
2 13k
1 18k
2 20k
Notes:
1) the 5V source could be the 12V rail, with a 68k resistor in place of 20k . Alternatively, you could use a -5V source through a 10k resistor and a 20k trimmer into the negative input of the opamp.
2) the 100k trimmer could be replaced by a 43k resistor and a 20k trimmer (the ideal resistance there is about 53k for minimum sine THD). At the correct trimmer setting, the sine from this circuit can have THD as low as 0.42%.
3) the 50k trimmer could be replaced with two 24.9k 1% resistors, if the rest of the resistors around the transistor circuit are also 1% (or not).
4) If the saw is fed directly to the sine trimmer through the 100k trimmer (e.g., using an SPDT On-On selector switch) then this circuit also gives a "sigmoid" (S-shaped) wave, which is a nice alternative to saw.
Frontpanel:
JHLivingVCO1.fpd in MOTM
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