Syncable VCLFO

[Martin Czech]

> Does anybody have schematics for a voltage controlled low frequency oscillator 
> that can be synced to the gate signal? That is, everytime you play a note, the 
> triangle wave should start from zero, go upwards and the continue from that. I 
> haven't seen this feature on any of the modulars around (Formant etc...). Of 
> course, a free running mode should also be available.  Preferrably a sine wave 
> output too.  

E.G. Roland 100M has such an LFO.

Take an existing circuit.
Then simply add a discharge switch (cmos, mosfet, bipolar) parallel to the timing cap.
The switch can be controled by a simple monoflop to enshure proper discharging.
Interesting: Programable voltage to set the "initial point". In case of a triangular
generator some extra logic may be required to set up the proper charging direction
after the sync.

m.c.