legato gate interface for FORMANT

Gate ICI 0O- R2 Gate II KOV EO D1 P1 R3 IC1 ... IC6 = 741 D1 ... D7 = 1N4148 15V O0 O 100k =Ow LED D2 0 R6 Cl 720n R1 P2 1k P3 legato gate interface for FORMANT Gate I m OR12 0 80595 This circuit is an expanded version of the interface receiver for the Elektor Formant music synthesiser. Its purpose is to allow for legato playing. By "Legato" (contrary to "staccato") we mean that the notes will run into each other smoothly without a break. That is to say, each key is pressed before the previous one has been released. As there must always be a key pressed no gate pulses will be produced and the envelope curves cannot be released. This disadvantage is especially noticeable with AD (attack-decay) envelope curves. This circuit differentiates the voltage transients from the KOV (keyboard output voltage) to provide a 2 ms signal which triggers the gate pulse. Although this method is only reliable when the portamento is switched off, musically it is of great significance. The input circui...