[sdiy] Ring mod and op amp

[Paul Perry]

At 10:36 PM 30/04/01 +0100, Seb Carr wrote:

>i was just going over a ring mod schematic (Ring mod version 1 by Aaron
>Cram, sorry forgot URL) and being a newbie with no elctronics training past
>gcse i was confused by the out put of the LM13700: the modulator output
>(from what i guess is a sort of buffering op amp) meets the outtput of the
>LM13700 and on the schematic this is shown as two little circles
>overlapping. Is this just a normal join in the wires/tracks or something
>else?

No, the two little overlapping circles is the control current input to the 
chip. That buffer thing is in fact on the chip, which consists of an OTA
(operational transconductance amplifier) and a buffer.

It would be worth loading down the chip data from National Semi or NJR,
there are a LOT of circuit applications on the data sheets.

paul perry (Frostwave analog fx) Melbourne Australia