Teledyne 4020 – Hydrocarbon analyzer (special version for automatic background gas switching) - Manual (Page 29)

Total Hydrocarbon Analyzer Operational Theory
Teledyne Analytical Instruments 11
Figure 2-1: View Inside Cabinet
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.
Refer to Section 5.5.4: Electrometer-Amplifier PC Board for more
information concerning the electrometer-amplifier and the other printed
circuits that follow.
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