J18
Ext. Range
Signal
Input
Ground
Lug
Back
of
Pot
Tip
Lug
R22
Variable Range
Control
n.c.
Switch
Lug
Figure 4-15: Connecting External Range Input Jack to Variable Range Pot (Opt. 3)
o
Var. Range Option 4: Manually Switched Internal/External Variable Range
Now it’s time for the banana jackers to regain the field. This option uses an extra
switch (Switch 44, a SPDT ON-ON switch like the Invert B switch) to provide
essentially the same functionality of Option 3 above. The extra switch,
Internal/External Variable Range Select, allows either the internal and external range
to be selected by flipping the switch. The disadvantage is that it requires more panel
real estate. However, before you non-banana jackers giggle too much, it should be
mentioned this arrangement does provide a level of convenience greater than Option
3. For example, if one is dynamically changing things during a Klee Sequence, this
allows one to switch between internal and external signals without having to
physically remove the plug from the External Range Input Jack.
The strap connections consist of a connection from the tip lug of the jack to the
switch, and from the switch center terminal to the right lug of the pot (as viewed from
the back). The connection from the switch to the pot will always be the same, but the
connection from the jack to the switch will vary, depending on if you want the switch
lever UP when it selects external voltage, or DOWN when it selects external voltage.
Both positions are illustrated here.
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