Disclosed are exemplary embodiments of devices for measuring voltage of a power supply. Also disclosed are exemplary embodiments of detection devices and temperature controllers comprising such devices for measuring voltage of a power supply. In exemplary embodiments, a device for measuring the voltage of a power supply generally includes a resistor, a capacitor, and a control unit. One end of the capacitor is connected with the resistor, while the other end of the capacitor is connected to ground. The control unit is connected with the power supply. The control unit includes a comparator connected with the capacitor, a reference power supply connected with the comparator, a timer, and a computing unit.