[sdiy] OTA subs & schemos WAS CA3080s purchased - now available in small er lots

[tomg]

Hi Tim,

> So here are the questions I have about this whole 3080/OTA thing:
>
> 1) What sort of adjustments or changes would you need to make to sub a
13600
> or 13700 into a 3080 circuit?

Don't use the buffer.

> 2) The 13600 is closest to the 3080, and the 13700 is a little more like
the
> 3280... right?

They are the same cell with different buffers.

> 3) What adjustments or changes would you need to make to sub a 13700 into
a
> 3280 circuit?

It works but it's not the same.

> 4) Where are some schematics for transistor/IC based 'roll your own' OTAs?

Normally for RYOs you don't want to use a opamp buffer because of the
offset, darlingtons are easier to deal with.

Have a look at the 3510 vcadsr. This uses a opamp buffer and a diff-pair
current source. I used a bi-fet opamp because it's a S/H circuit.
http://www.ele4music.com/pdfs/3510.pdf


Regards
Tom