B. Power Supplies
Thermoelectric coolers operate from a DC power input. These DC power supplies can range from simple batteries to sophisticated closed loop temperature control/power supply circuits. Both linear and switching power supplies can be used to operate TECs. The "quality" of the DC current is important. High-quality DC current is smooth and constant with very low ripple or noise. All current derived from AC sources contains ripple. Ripple is significant because it can affect the performance of the TEC. Unfiltered full-rectified AC voltage has a ripple factor of approximately 48%, which can decrease the performance of the TEC by as much as 23%. Marlow Industries recommends limiting the ripple factor to less than 10%, which will reduce the loss in performance to less than 1%. Listed on the following page are some examples of power supply circuits.