Lectrosonics VS1 - Manual (Page 7)

INSTALLATION
The VS1 has eight logic inputs, eight logic outputs, and a video synchronization input. The logic inputs provide the
interface to an automatic microphone mixer (or other device that generates logic output signals). The logic inputs
will accept a switch or relay contact closure or a saturated transistor (eg. an optically isolated LED-Phototransistor
combination). The video synchronization input accepts a gen-lock signal from a master timebase and strips the
vertical retrace pulse. This allows the VS1 to key the video switcher for a camera change without introducing any
rolling or other video anomalies associated with non-synchronized video switching.
Installation of the VS1 is quite straightforward. The following instructions assume the use of a Lectrosonics
AC1/AP4 Automatic Mixer or VS1 Automatic Pre-Processor, but the VS1 is compatible with virtually all automatic
mixers that provide logic outputs. If a non-Lectrosonics automatic mixer is to be used with the VS1, please consult
the factory for interconnection details.
Logic outputs from an automatic mixer are connected to the logic input terminals of the VS1. Note that multiple
logic outputs may be connected to a single logic input if necessary. This allows more than one microphone to
activate a particular camera. The "+" terminal of the logic output from the automatic mixer is connected to the "+"
terminal of the logic input on the VS1. In the same way, the "-" terminals are connected together.
The logic output terminals from the VS1 are connected to the appropriate inputs on the video switcher. The logic
outputs of the VS1 are optically isolated NPN transistors. The "+" terminal is the collector of the NPN transistor,
while the "-" terminal is the emitter. Since channel activity forces the NPN transistor into conduction, connections
may be made to the logic output terminals that provide either active high (pull up) or active low (pull down) signals
during periods of channel activity. Refer to the logic output connection diagram below for details of the logic output
connection.
Figure 5 - VS1 Logic Input/Output Timing Diagram
If the override capability of the VS1 is to be utilized, a switch should be connected to the logic input terminal of the
desired override output. The switch will provide a manual override.
If the cameras in the system are driven by a common timebase, the system synchronization signal from the
timebase may also be input into the 75 Ohm Sync Input. This allows the VS1 to initiate camera switching only
during the vertical retrace interval.
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