My first VCF

[The Dark force of dance]

Y-ellow Y'all.
        And just out of interest. The difference between a 13600 and a 13700
is that the 600 has a control path between the Iabc and the darlington
buffer. The bias on the darlingtons are biased up with Iabc. However the
13700 does not have this. It's output stage is just a straight up buffer.
You have to look fairly closely at the data sheets but it's there.

I couldn't prattle off the exact nature of this bias adjustment off hand but
it's an attempt to compensate for output impedance if I recall. Which
changes with Iabc. But don't quote me on this go look at the datasheets.

As I recall noting: This is probably a good idea but more trouble than it's
worth! However I've been long suffering with the 13600 part because all the
NSC reps down here said that they no longer make the 13700. According to
them they were discontinued 10 years ago. Yea Right! So you kinda learn to
adapt I guess.

The output of the OTA is high impedance. Use a FET or a hi-z op-amp. 

Hope this helps.

Be absolutely Icebox.
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