Figure 4-11 Autobias Circuit Block Diagram - ferrotec Temescal CV-12SLX User Manual

4.3 FPS Theory of Operation
Autobias
ON In
Gun
ON In
HV
Is ON
Emission
Monitor In
HV OFF +
Remove Clear
Gun OFF
4.3.4 Filament Output Section
The filament output section of the FPS connects the filament power with the negative HV. The
filament power and the HV are connected to the filament by a two-conductor cable. The high
voltage (0–10 kV) from the HV Power Supply enters the FPS via J301. On standard FPS units
(PN 0620-6604-0), the high voltage is routed to the vacuum relay (K101). On such units, K101
either connects the negative HV to the secondary of the filament transformer or applies a
ground to the secondary of the filament transformer. The relay is driven from the Filament
Supply PCB via J103 pins 5 and 6.
FPS units with PN 0620-6604-0 omit the vacuum relay. On those units, the high voltage is
connected to the secondary of the filament transformer T1, which has a 10:1 ratio. The filament
transformer connects the high-voltage, low-current output of the FPS to the filament with low-
voltage, high-current filament current, superimposing the negative DC HV on the AC filament
current.
CV-12SLX User Manual

Figure 4-11 Autobias Circuit Block Diagram

AND AND
Comparator
Ref
Threshol d
Latch
Remove Clear
C lock
Clock
Stop
IN V OR
Osc
INV
Filamen t
An alog
Current
Switch
Request
Autobias Set
8 Bit
8 Bit Scal ing
Up
D/A Amplifier
Counter
Ref
4-12
Section 4: Theory of Operation
To emission current
Analog
loop compensation
Switch
summing junction
0101-8292-0, Rev. C