Page 34
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X-Frame
™
88 Designer’s Manual
CV Input Rotary Control Interface
The next illustration shows the same CV port using an external rotary control as the external device. This is a common sce-
nario, as wall controls are often implemented for use as audio volume controls.
Notice in the illustration that only two wires are connected to the rotary control. The scenario is the same as the switch in the
previous example. We are taking the supplied voltage from the X-Frame 88's CV port, Pin 2 and connecting it to one side of
the control. The other side of the control is carried through back to the CV return pin, Pin 1. In this configuration, the control
is a variable resistor. It is very important to note that this is NOT a potentiometer, as there is not a third connection (ground)
carried out to the control. All that is required to activate the CV port is a voltage within range of 0-10 Volts on the return pin of
the port.
You can convert the above configuration into a true potentiometer by moving the wiper to the “IN” terminal, the top of the con-
trol to the “+” terminal, and bringing the ground terminal out to the bottom leg of the pot. This ground connection can be
found on the second row of pins. If you require this configuration, you should use a 10k Ohm linear taper potentiometer for
best results. Normally this is not required for simple rotary controls. All that is required is that the voltage be returned to the
IN pin, via whatever analog device that is needed for the application. The connection is the same for many other external
devices. Essentially, you can use anything that will either return the DC voltage to the IN pin, or vary the voltage between the
pins, as in the above example with the rotary control. For information on how to calibrate the software side of this configura-
tion, please see pages 36-37 or refer to the online help for MediaMatrix
®
MWare
®
3.1.2 or X-Frame
®
88 software.
Equivalent DC Circuit
10 V DC at “+” terminal
CW
Voltage return at “IN” terminal
MERIDIAN, MS MADE IN U.S.A.
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