From gstopp@fibermux.com Thu Dec 7 09:42:47 1995 7 Dec 95 12:42:42 +0500 5 Dec 95 19:50:32 +0500 From: gstopp@fibermux.com Date: Tue, 05 Dec 95 16:35:21 PDT Encoding: 35 Text Subject: Re: Linear FM on SEMs? Regarding adding linear FM to the SEM VCO - Get ready for techno-blab - looks like experimentation would be needed here, as the exponential converter uses the Moog-Hemsath method meaning that the reference amplifier has the (-) input going to ground rather than the (+) input due to the inversion added by the high-frequency track transistor (I'm getting this out of a book). So, the advice would be to take a resistor of about 300K and connect it to either the (+) input or the (-) input of the 741 reference amp (A3 for VCO 1, A8 for VCO 2) and apply the modulating voltage to the other end. If it goes the wrong direction (frequency gets lower as the voltage goes up), try the other input. If the sweep range is too narrow, use less than 300K. If the sweep range is too sensitive, use more than 300K. If none of this works, try something else. If the VCO blows up (which I doubt would happen), don't blame me. Good luck! - Gene gstopp@fibermux.com Subject: Linear FM on SEMs? Author: MAGER@bitstream.mpls.mn.us at ccrelayout Date: 12/4/95 7:27 PM 1) I'd like to implement linear FM on at least one oscillater per SEM. does the SEM include a log-->linear CV converter on the way to it's VCOs' CV inputs like many other synths, and does anybody have tips for bypassing it? I'd like to have CV patch points w/ exp & lin response so that I could avoid the frequency shift inherent in exponential FM, but still CV the pitch (or 'average pitch') around with the min-sequencer/kenton/whatever.