The quality of cement is usually determined by destruction of the samples. Moreover, this process lasts from seven to twenty-eight days. To speed it up decided young technicians of the radio circle of the pioneer city of Iskitim of the Novosibirsk region. “The task we were given in Vries cement plant — said the group members Zaitsev. — Together with the guys we have designed and built an instrument (Fig. 1), which brand of cement you can determine almost instantly”.
The device operation is based on the phenomenon of reflection of light rays. Different quality of cement has a different reflectivity, for example a cement of mark 200 is almost white, and brand 1000 black. Thus the laboratory directly to the mill can give the comparative characteristics of the material being manufactured.
Sensor B1 (Fig. 2) — selenium photocell in an electrical circuit which includes the microammeter PA1 to 50 µa. Light source — two parallel-connected lamp voltage is 2.5 V. They are fed from the four elements “332” or pyativoltovy rectifier.
Fig. 1. The appearance of the device to determine the cement type.
Fig. 2. Schematic diagram of the device
In a container for samples of cement paste reference the record of a certain color and with the help of rheostat R3 is set so the heat from lamps so that the needle is located in the middle of the red sector. Then the switch S2 is transferred to the “work” position and set the arrow in the middle of the blue sector.
The reference plate is removed and fill the container with cement. Now, depending on the type of material the meter pointer will deviate to the right or to the left.