Agilent Technologies 1100 Series Reference Manual page 269

Photomultiplier Tube Voltage Supply
The photomultiplier tube needs an adjustable working voltage between -240 V
and -820 V for correct operation. The PMT gains are realized by variable
operating voltage of the device. A regulated pulse width modulator is used to
generate the high voltage by switching the 24 V rail to a transformer. The
feedback loop has a D/A-converter-controlled base voltage to set the desired
output voltage. The PMT output delivers a current signal which is proportional
to the detected light and to the actual working voltage.
FLL
Board
EX Mono-
chromator
Flow
Cell
Figure 92
1100 Series FD Reference Manual
FLM
Board
FLF
Flash Lamp PMT voltage
Supply Supply
EX Motor
Driver
Cell Read/Write
Detection Port
FLM
Board
Block diagram FLF
Board Temp
Sensor
PMT
Pre-Amplifier
&signal
conditioning
Lamp Cover A/D Converter
Safety Switch 16-bit
Theory of Operation
Reference
Diode
Signal
conditioning
&gain
Leak Sensor Leak
circuit Sensor
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