© 2005
WTC3293-14000 BO
ARD
WITH DISPLA
Y
PAGE 5
WTC3293-14400-A Rev E
OPERATING THE WTC3293-14000
STEP 6: ADJUST THE SETPOINT TEMPERATURE
The setpoint temperature can be adjusted from 10 to 65°C either by using the onboard 12-turn
potentiometer.
The VSET wire pads can be used as test points to monitor the potentiometer setting or for
connecting an external voltage source (such as a function generator). If an external voltage source
is used, set the setpoint potentiometer approximately mid-range (1 to 1.5V). The input voltage
range is 0 to 2.5V which corresponds to 0 to 25k
Ω
of thermistor resistance. [Transfer function is
10k
Ω
/ V.]
STEP 7: ENABLE THE OUTPUT CURRENT & MONITOR IN-RANGE STATUS
The switch next to the In-Range indicator enables and disables current through the thermoelectric.
The green LED on the In-Range indicator lights when the actual temperature is within 0.05°C of the
setpoint. If the actual temperature exceeds the setpoint, the upper LED will light. If it is below the
setpoint temperature, the lower LED will light.
STEP 5: VIEW THE SETPOINT and ACTUAL TEMPERATURE
The switch next to the setpoint potentiometer determines whether Setpoint or Actual temperature
is displayed. When the setpoint is displayed, the rightmost decimal point is lit. The resistance to
temperature conversion software assumes the thermistor bias current is 100
µ
A and the thermistor is
characterized by the Steinhart-Hart relationship:
where T is in Kelvin; R is in ohms, A =
1.1279E-3; B=2.3429E-4; C=8.7298E-8 (TCS-610)
If another thermistor or bias current is used, the temperature display will not be properly calibrated.
To use another sensor or change the calibration, contact the factory.
1/T = A + B(ln R) + C(ln R)
3
Setpoint Potentiometer
Setpoint/Actual
Display Select Switch
In-Range Indicator
Enable/Disable
Switch
