[sdiy] Ring mod and op amp

[Tony Allgood]

The double overlapping circle in most circuits depicts a current
source/sink. This in respects to the LM13700 represents its output
stage, which is controlled by the amplifier bias current (Iabc), which
comes in via a another pin. What makes the 13700 more 'complex' is the
provision of an onchip buffer, that can or cannot be connected to the
OTAs current output. Many circuits chose not to use this buffer, because
of DC offset problems. The buffer is normally shown as a triangle or
sometimes as a darlington transistor.

But one of the nicest things about current outputs is that they can be
joined to other outputs to form a sum of both output currents.

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan