2 • 65-2434RK CO Transmitter
Description
This section describes the components of the CO transmitter. The transmitter consists of
the CO sensor, charcoal filter, amplifier printed circuit board (PCB), and enclosure.
Figure 1: CO Transmitter Component Location
CO Sensor
The sensor is cylindrical with the sensing face on the top and the connection pins on the
bottom. The sensor plugs into the amplifier PCB with the four pins. The sensor is exposed
to the ambient air through an opening in the enclosure cover. Through a series of chemical
and electrical reactions, the sensor produces an electrical output that is proportional to the
detection range of the transmitter.
Charcoal Filter
The disc-shaped charcoal filter is secured to the sensing face of the sensor by a rubber
boot. The filter prevents interference gases (hydrogen sulfide [H
2
S] and certain
hydrocarbons) from producing false CO readings.
Amplifier PCB
The amplifier PCB converts the electrical output from the sensor to a 4 to 20 mA signal
(that is proportional to the detection range) and transmits the signal to a gas monitoring
controller. The amplifier PCB includes the interconnect terminal strip, sensor sockets, span
pot, zero pot, and test points (see Figure 1).
Amplifier PCB
Zero Pot
Span Pot
Test Point CAL-
Factory Set Pot
Amplifier PCB Mounting
Screw (under sensor)
Cable Bushing
Amplifier PCB
Mounting Screw
Sensor (w/charcoal
filter & boot)
R
CAL-
TB1
CAL+
+V
FB
B
SPAN
Enclosure
(shown w/out cover)
Interconnect
Terminal Strip
Test Point
CAL+
ZERO
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