Many (but not all) video synthesis modules need sync signals to synchronize synthesized waveforms with the scanning of the electron beam in an analog display. (LCDs of course do not work this way, but a composite video signal embeds horizontal and vertical sync pulses whose timing defines the screen resolution.) Basically any signal you want to be stationary instead of free-running needs to be synchronized to the same time base as the display. Stuff like oscillators and ramps need a sync input, other more processing-oriented analog modules generally don’t since they just transform an existing signal. On the Vidiot the push buttons toggle synchronization of the vertical and horizontal oscillators, or you can manually sync them with their 3.5mm sync input jacks.
Sync connections in LZX have gone through three different forms:
- over the CV/gate lines on the Euro power bus
- over a dedicated 14 pin ribbon cable for sync
- over an RCA connector carrying “composite sync” which includes both vertical and horizontal sync pulses. This is used by all new modules and is also compatible with a lot of broadcast gear.
More details on specific modules here.
