Gamma Vacuum SPCe - Figure 52: Current Output

Figure 52. Current output
Output current or pressure (Pin 12)
Pin 12 is a buered voltage output that is proportional to the HV output
current and can be used to monitor the HV current. The scaling factor
defaults to 1 V per 1 mA out. This factor is scaleable from the front panel of
the SPCe.
Logarithmic Current (i) Examples:
Example 1
Oset = 8
Current = 2 x 10
-8
(20 nA)
Step 1: Calculate the log of the current (Log (2 x 10
-8
) = -7.7)
Step 2: Add the oset
value (-7.7 + 8 = 0.3 Volts = V
pin12
)
Example 2
Oset = 8
Current = 5 x 10
-6
(5 uA)
Step 1: Calculate the log of the current (Log (5 x 10
-6
) = -5.3)
Step 2: Add the oset value (-5.3 + 8 = 2.7 Volts = V
pin12
)
Example 3
Oset = 7
Current = 2 x 10
-8
(20 nA)
Step 1: Calculate the log of the current (Log (2 x 10
-8
= -7.7)
Step 2: Add the oset value (-7.7 + 7 = -0.7 Volts, V
pin12
therefore = 0 and is
at the bottom of its range)
Logarithmic Pressure (p) Examples
Example 1
Oset = 10
Pressure = 1 x 10
-9
Torr/mbar/pascal
Step 1: Calculate the log of the pressure (Log (1 x 10
-9
) = -9)
Step 2: Add the oset value (-9 + 10 = 1 Volt = V
pin12
)
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