A proportional integral control algorithm designed into Oven Industries’ 5R7-573 open-board temperature controller adds more precise control to thermoelectric (Peltier effect) modules. The solid-state H bridge control offers seamless transitioning between heating and cooling to eliminate dead spots—a red LED indicates heating mode, and a green LED indicates cooling mode. Pulse-width modulation controls the thermoelectric module’s power level at a base frequency of 900 Hz. Power resolution is one of ±255 steps in the load circuit control. TTL-to-USB communication is available via an optional OI-TTL-Cable. Input voltage ranges from 6 to 28 V dc; output voltage from 0 to 36 V dc. Load current is 0.1 to 12.5 A. Operating temperature ranges from ‒40 to 250°C, with control stability of ±0.1°C. The device measures 1.2 by 2.7 by 2.9 in.