A portable conductivity meter controlled by singlechip computer was designed. The instrument uses conductance-frequency transformation method to measure the conductivity of solution. The circuitry is simple and reliable. Another feature of the instrument is that the temperature compensation is realised by changing counting time of the timing counter. The theoretical based and the usage of temperature compensation are narrated.
Usually, the situation should be avoided that the resonant frequency of crystal changes with temperature. However because the precision of the crystal resonance frequency is quite high, the temperature measurement can be realized by utilizing the relation between the resonant frequency and temperature. Its principle, measuring method are discussed and the experimental results are demonstrated in this paper.
When CCD is used in multichannel spectral detector, it is output accompanied with noises and distortion because of the device working in the condition of lower lighting, and because of the sensitivity of CCD different from the wavelength. The paper is focused on how to get a good signal by clearing up the signal out from CCD.