Teledyne 4030 - Total Hydrocarbon gas analyzer - Manual (Page 15)

Introduction
Teledyne Analytical Instruments 13
Figure 2-1: Flame Ionization Cell
The electrode section of the cell may be removed for inspection by
turning off the power, disconnecting the electrode lead plug, and
removing the screws, which retain the electrode assembly in the sensor
body.
2.3.1 Electrometer-Amplifier
The collector cable is coupled directly to a coaxial fitting located on
the electrometer-amplifier PC board. The PC board is located on the side
panel next to but outside of the isothermal chamber. See Figure 2-1 and
consists of an electrometer amplifier and an operational amplifier. This
circuit is a very high-gain, current-to-voltage converter circuit, having
an input impedance measuring in the billions of ohms. It is static
sensitive and highly susceptible to contamination. Special care must be
taken in handling this PC board.
2.3.2 Anode Power Supply
The high voltage anode power supply components are mounted on
the anode power supply printed circuit board. High voltage regulation is
achieved through the use of series-connected zener diodes. The
simplicity of this circuit’s design can be attributed to the extremely low
current demand of the anode circuit. The positive output voltage is