Thermocouples galvanometer with

Around 1900, W. W. Coblentz used a salt prism to build a primitive infrared spectrometer [4,5], It consisted of a galvanometer attached to a thermocouple to detect the IR radiation at any particular wavelength. Coblentz would move the prism a small increment, leave the room (allowing it to re-equilibrate), and read the galvanometer with a small telescope. Readings would be taken for the blank and the sample. The spectrum would take an entire day to produce and, as a consequence, little work was done in the field for some time. 

Thermocouple gauges work on a similar principle but have a thermocouple as sensor connected to a heated platinum filament. The e.m.f. of the thermocouple is measured with a galvanometer or potentiometer. Such gauges have a normal working range from 10 to 10" Torr, but otherwise have characteristics similar to Pirani gauges. 

The Boyd and Harkins reference might be considered the first careful calorimetric work taking into account the special problems of immersional calorimetry it was also the first such work in which surface areas could be assessed (the B.E.T. method) as a necessary auxiliary for putting values on a imit area basis temperatiue changes were measured with a 36-junction thermocouple and a White double potentiometer with a sensitive galvanometer. 

Electric Instruments, Many and various kinds of electric instruments are used in industrial processes and in analytical and research, laboratories, including those dealing with expls and ammunition. Among such instruments may be mentioned ammeters, voltmeters, galvanometers, thermocouples, ohm meters, wattmeters, frequency meters, oscillographs, computers, etc... 

The Leeds Northruj) transformation-point indicator is a semiautomatic recorder giving a continuous curve of temperature temperature difference. The complete apparatus includes the recorder, two wall-type double-suspension galvanometers, furnace, rheostat and thermocouples. The recorder is the potentiometer type with a drum chart. The potentiometer slide wire is mounted on the same shaft as the... 

The sample to be studied is ground to —80, - -100-mesh size and placed in one of the holes of the nickel block. The second hole of the block is filled with calcined alumina which does not undergo any thermal change in the temperature range of study. Two sets of Pt — Pt Rh (13 %) thermocouples are placed and connected to a very sensitive galvanometer. In the third hole is embedded a thermocouple which measures the temperature of the block. 

Fig. 4.10. Scheme of experimental setup for studying TSC in movable joints Ml-P-M2 (1) lever load unit (2) aluminum cylinder with a polymer coat on the face (3) thermocouple (4) polymer coating (5) copper disc (6) potentiometer (7) galvanometer (8) copper needle... 

A comparison of indicated temperature rise with calc ilated temperature rise from current and voltage readings indicated a time lag in the surface thermocouple of 0.2 ms. This represented the composite lag in galvanometer response for the three readings of current, voltage, and temperature and any apparent lag due to unbalance in the thermocouple circuit which may have caused induced voltage pickup. 

Thermocouples, also called thermopiles, in which several couples are combined electrically, played an important role as infrared detectors in the last decades of the nineteenth and the first half of the twentieth century. Thermocouples provide low impedance energy converters, well-suited to drive sensitive galvanometers. Before the use of electronic amplification this was of great value. Even today many laboratory spectrometers still use thermopiles, but, in nearly all cases, with electronic amplifiers and recorders. An excellent discussion of various constmction techniques and test results of thermoelectric detectors is given by Smith et al., (1957). 

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