Two schematics with explanation in EDN Design Ideas: http://www.edn.com/Home/PrintView?contentItemId=4407476 Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Samples for the Waldorf Blofeld: http://Synth.Stromeko.net/Downloads.html#BlofeldSamplesExtra