1. Thermopile infrared detectors and sensors

2. An improved net radiometer having a 30 windings half copper-plated constantan thermopile is described.

3. The Bolometer Nature AN instrument a thousand times more sensitive to radiant heat than the thermopile, and capable of indicating a change of temperature as minute as 1-100,000th of a single

4. Typically one or more regular batteries must be installed to operate it, although some so-called "power stealing" digital thermostats use the common 24 volt AC circuits as a power source, but will not operate on thermopile powered "millivolt" circuits used in some furnaces.