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Cygnus 2 Operating Manual
Proceed to the SOURCE screen and choose the Source that is going to be defined
as the turret source. This is accomplished by Editing the chosen Source as follows:
1 Designate the Number of Crucibles; for example, four.
2 Select the Crucible Output. This defines the number of the first relay that
encodes the crucible number selected by the active Material. Relays are
defined sequentially with the first relay containing the least significant bit (LSB).
The greater the number of crucibles selected, the greater the number of relays
required. The number required is based on binary encoding (actual coding is
binary -1, with 00 representing position 1 and 11 representing position 4). Any
unused sequence of relays may be used if it is long enough to provide sufficient
selections. Outputs are NO (Normally Open).
3 Determine whether Turret Feedback is desired. This allows the turret position
controller to stop further Cygnus 2 processing until the requested turret position
is satisfied. If chosen, a turret input must be connected to the turret position
controller’s feedback signal.
Enter a Turret Delay Time which allows an adequate time for positioning to take
place. Once the delay time has expired, Cygnus 2 state processing continues.
4 The selection of a particular crucible for a Material is defined in the Material
page.
3.5.3 Auto-Z
The Auto-Z feature of Cygnus 2 automatically determines the Z-Ratio of a crystal.
This feature is enabled on the SENSOR page of the SENSOR screen. For the
theory behind Auto-Z, see section 14.1.6, Auto-Z Theory, on page 14-9.
The following information briefly describes Auto-Z and details the conditions under
which a crystal is "unable to Auto-Z".
Auto-Z is calculated based on the slightly different mass sensitivities of the
fundamental and the first anharmonic resonances of the quartz crystal oscillator.
Therefore, the need to measure the frequencies of both the fundamental and the
first anharmonic resonances is critical.
When inserting a monitor crystal and attempting to Auto-Z, the fundamental and
anharmonic frequencies are measured to determine the status of the crystal. The
crystal status may be classified into four categories:
1 New Crystal
The first category is for a "new" crystal, one that does not have any material
deposited onto it. If both frequencies fall within the allowed range for new
crystals, Cygnus 2 will allow an Auto-Z calculation with this crystal.
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