Model menu
Programmable mixers
F X - 4 0
If necessary, the mode of the Offset mixer can now be
changed; two modes are available:
Manual control: when you operate the switch, the
servo runs to the Offset position selected under ‘ON’,
at the set speed and with the set delay, and remains there
as long as the switch is in the ‘On’ position. The servo only
moves again when the switch is moved back to the ‘Off’
position; it then returns to the starting position - as set
under ‘OFF’ - using the set speed and delay.
Timer control: in this mode the servo runs to the pres-
cribed ‘On’ position, as described for manual control,
when the switch is operated.
However, in contrast to manual control, it does not stay in
this position, but returns automatically to the starting point
when the pre-set dwell time (Duration) has elapsed.
This Offset mixer is very convenient, and can be used to
implement sequences involving up to four functions, either
under manual or automatic control.
Typical practical applications include the sequential retrac-
tion and extension of a scale retractable undercarriage,
whose functions can be controlled very accurately. By set-
ting the times carefully, you can arrange for various wheel
doors to open in turn, after which the wheels then extend.
The Offset value can be entered as a percentage figure in
the ‘Offset’ fields, separately for the ‘On’ and ‘Off’ states:
mark the appropriate field, and adjust the settings in the
familiar way using the arrow buttons. The adjustment range
is +300% to -300%. The default setting is 0%; marking the
‘Reset’ button restores the defaults.
Fine-tuning is also available for the Offset mixers. The first
step is to define a transmitter control in the appropriate
column, using the transmitter control select menu as pre-
viously described. After this you must set the effect range in
the ‘Rate’ field using the arrow buttons; the adjustment
range is +100% to -100%. The default setting is 0%; mar-
king the ‘Reset’ button restores the defaults. The transmit-
ter control you select for fine-tuning an Offset mixer also
has four operating modes; they are absolutely identical to
those of a normal mixer (see page 61).
You may also wish to optimise the servo transit speed for
the task in hand: the speed of the servo can be adjusted in
small increments, separately for the ‘there’ and ‘back’
directions. The adjustment range is 0 to 27 increments. Ple-
ase note: the higher the number, the more slowly the servo
moves. The maximum value (27 increments) corresponds to
a duration of nine seconds. The default setting is always ‘0’.
When you mark one of the fields ‘there’ or ‘back’, the but-
ton fields for the arrows appear at the right margin. It is pos-
sible to make adjustments in steps of one increment or ten
increments. Pressing the ‘Reset’ button restores the default
setting.
A delay time can be programmed using virtually the same
procedure; delays in the range 0.0 to 9.9 seconds can be
set, separately for the ‘Start’ and ‘Stop’ phases. Pressing
the double arrow buttons increases or reduces the delay by
one second; operating the single-arrow buttons produces
increments of 0.1 second.
The programming of an Offset mixer is concluded by acti-
vating a switch using the standard procedure: mark the cor-
responding button field in the bottom line, and define the
switch in the switch select menu which then appears. The
direction of effect of the switch can also be set in the usual
way. The status of the mixer is displayed as ‘On’ or ‘Off’ -
according to the position of the switch - in the left field in
the bottom line.
OFFSET MIXER AS MOTOR-CUT SWITCH
Offset mixers also offer the possibility of mixing a fixed
value into the primary channel. This value can be up to
300%, as shown in the screen shot. This facility can be
used, for example, to make absolutely certain that the
motor of an electric-powered model cannot burst into life
unexpectedly, even if you move the throttle stick by mis-
take; this is a very useful safety feature. If you program an
Offset mixer, and set the Offset value to -300%, the throttle
stick can be moved to any position without the motor star-
ting, because it is impossible for the stick travel to override
the value set by the Offset mixer. The motor can then only
be controlled in the normal way if you first disable the Offset
mixer by operating the associated switch. This switch is not
interrogated during the safety switch query when the trans-
mitter is switched on.
SERVO CENTRE ADJUSTMENT
The comprehensive nature of the FX-40’s programmable
mixers makes them suitable for a very wide range of special
functions. As a further example we will mention here the
possibility of correcting the neutral position of the wing or
elevator servos using an analogue or digital trimmer.
All you have to do is select the hardware control (‘H/W’) you
wish to use, and mix a small input into the servo output you
wish to adjust.
This constitutes an ultra-fast method of correcting any mini-
mal control surface deviations which show up just before a
flight.
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