Our new thermoelectric cooler temperature controller (TE-TC) is a low-cost precision temperature controller with low-noise constant current power supply for precision temperature control. Front panel controls allow operation in two modes; in a constant current temperature mode or in a constant resistance mode (for uncalibrated resistors).
The TE-TC can control temperature with a linearised thermistor (typically a bead thermistor of resistance 8.2kW at 25°C, although other selected thermistors are possible) or worked in controlled resistance mode with any thermistor used by customer.
Proportional Integral Derivative (PID) control minimises overshoot, eliminates steady-state error and allows fast settling time to selected temperature from switch-on. The microprocessor uses autotuning PID so that single, two and three stage coolers can be used interchangeably without setting any control constants.
Digital display by seven segments LED allows observation of either set values or measured values of temperature ( °C), resistance and current. The display can toggle switched to SET or READ by the mode switch button. Units displayed are selected by the display UNITS push button. With display in SET readout mode the SET point can be modified by two push buttons which increment or decrement the display. Adjusting the front-panel trimmer sets current limit. The output current can be displayed.
The current limit is set control (trimmer on front panel) prevents accidental overload of Peltier cooler. If the sensor goes open circuit the output is switched off and the message - OC - appears, to represent open circuit. Similarly, if the sensor reads less than 20 ohms the output is switched off and message - SC - appears, to indicate short circuit.
In temperature mode the setting accuracy and long-term control are ± 0.01°C and short-term control is better than ± 0.01°C.
In resistance mode, and with thermistor resistance in the range 3KOhms to 10KOhms at 20°C, similar results are obtained. Higher values give similar stability but less setting accuracy.