Teledyne Tablet Accessory T803 Manual De Usuario

Teledyne API T803 CO2/O2 Analyzer Operation Manual 

Principles of Operation 

 

 

 

12.6.3.2. WATCHDOG CIRCUITRY 

The most important of the status LEDs on the relay board is the red I

2

C Bus 

watch-dog LED.  It is controlled directly by the analyzer’s CPU over the I

2

C Bus.  

Special circuitry on the relay PCA watches the status of D1.   Should this LED 
ever stay ON or OFF for 30 seconds, indicating that the CPU or I

2

C bus has 

stopped functioning, this Watchdog Circuit automatically shuts off all heaters.   

12.6.4. HEATER CONTROL 

12.6.4.1. TEMPERATURE CONTROL 

At low magnetic field strengths levels, paramagnetic molecules follow Curie's 
law to good approximation, which indicates that the susceptibility of 
paramagnetic materials is inversely proportional to their temperature.  

To minimize the effects of temperature variations on the O

2

 concentration 

measurement the parametric sensor is raised to a high temperature level, 50

C.  A 

cartridge heater implanted into the sensor is the heat source.  The temperature of 
the sensor is measured by a thermistor also inserted into the sensor body. 

07276B DCN6418