We found this circuit in a Poptronics from the 90's. Equivalent operational amplifiers can be used. The circuit must be supplied by a symmetrical source.
This circuit is part of a synthesizer that was published in parts in several issues of Radio...
This symmetrical or dual source without regulation is indicated for the feeding of experimental projects...
Integrated LM108 and LM101A are used in this fast adder with low input current, figure. The...