Rane RPM 22 - Manual (Page 7)

Manual-5
Preset Recall Using Contact Closure Switches
The minimum “low” voltage required to detect a contact closure
and change Presets is 2.5 V. Since the internal pull up is 100 kΩ
to +5 V, it is possible to calculate the maximum allowable cable
length, provided the wire resistance per foot (or meter) is known.
Example:
To be safe, allow a maximum of 80 kΩ cable resistance. This
value keeps the voltage divider formed by the 100 kΩ internal re-
sistance and 80 kΩ cable resistance from dropping below 2.5 V.
(5 V * 100 kΩ) / (100 kΩ + 80 kΩ) = 2.777 V
If the cable resistance is 30 Ω per 1,000 feet
(1,000 feet / 30 Ω) * 80,000 Ω = 2,666,666 feet.
Thus, you can only use 2,666,666 feet (505 miles) of twisted
pair cable before the Preset recall functionality becomes inter-
mittent (assuming the cable is properly twisted and not run
through excessive magnetic or electric fields).
MRS 4 Memory Recall Switch
The MRS 4 provides a simple solution to recalling Memories
from a remote location using the VIP (Versatile Input Port). The
MRS 4 allows up to four Memories to be recalled. These are
radio buttons: engaging one button (in, changing to green) causes
any of the other three to disengage (out, changing to black). Space
is provided next to each button for labelling.
Remote Level Control Using Potentiometers
The VIP inherently prefers linear taper 10 kΩ potentiometers,
which provide a nice audio taper “feel” for the end user. When
used with suitable twisted pair wiring, the 10 kΩ value also of-
fers acceptable noise immunity and very long cable lengths.
VR 2 Volume Remote
The Rane VR 2 Volume Remote or LRS 4 Level Recall Switch
accessories are suitable candidates for a remote volume control.
Connect the remote's control voltage Vc (wiper) connection(s)
first. Then connect the voltage reference “Vr” on the VR 2 to the
“REF” terminal on the RPM 22. Connect the GND (ground)
terminal last. Double check your wiring before applying power
to the RPM 22 since improper wiring can and will cause perma-
nent, irreparable damage to the remote, requiring replacement.
1N4001
+12
pin 1
2 kΩ
+12
pin 1
(examples for VOP pin 1)
VOP CONNECTION
Light an LED Relay Drive
100 mA coil
Crydom P/N D1225
current max
pin 1
+12
24 to
3
4
2
1
140 VAC
25 A max
Line Voltage Switching
NOTE: +12 VDC is available on the VOP. An external supply may be used as long as any VOP pin voltage never exeeds 40 VDC.
Examples shown are for 12 VDC only.
Rane MRS 4 Memory Recall Switch and VR 2 Volume Remote.
4
0
2
6
8
10
LEVEL
Versatile Output Port (VOP)
Eight open collector logic output pins are provided, each capable
of sinking 100 mA of current. The on-board REF voltage of
12 VDC provides a maximum of 200 mA of current. Use an
external power supply (40 VDC maximum) if more current is
required, but be sure to connect the external supply’s ground to
the GND pin on the VOP.