Manual

TELEDYNE ANALYTICAL INSTRUMENTS

2.0 Operational 2.0 Operational

2.0 Operational

TheorTheor

Theor

During calibration, the bridge circuit is balanced with the reference

gas; the zero of each range is set with its zero gas and the high end of the

range is adjusted with span gas. The intervening points along the range (or

ranges) of interest will produce a DC electrical signal representative of the

analysis.

2.22.2

2.2

Electronic ComponentsElectronic Components

Electronic Components

The temperature of the measuring and reference cell block is regulated

to within 0.1°C by means of an electronic proportional controller circuit.

The cell block is mounted on an aluminum heater block and insulated. A

thermistor is used in the circuit to keep the heater block at a predetermined

temperature.

A regulated current supply of approximately 100 milliamperes supplies

stable temperature-independent power to the sensor elements in the cham-

bers. Since the elements are connected to the four arms of the Wheatstone

bridge, a gas with a thermal conductivity different from the reference

creates an imbalance in the bridge in proportion to the thermal conductivity

of the sampled gas. This signal is amplified and displayed.

The output of the final buffer amplifier is normally 1 volt full scale,

and is powered by a standard TAI power supply unit of +15V and -15V.