Banajit Chakraborty, T K Maiti
（Department of Applied Electronics and Instrumentation Engineering, Netaji Subhash Engineering College, Kolkata 700152, India）
Abstract： This paper describes the design and development of the timer based on liquid level measurement system in which timer 555 is used in astable mode. The capacitor charging time i.e. the ON time pulse width of the timer output waveform which is measured using a digital storage oscillator (DSO), is linearly proportional to the capacitance of a co-axial cylindrical capacitive transducer, and this capacitance once again linearly varies with the change in liquid level. Hence, we obtain a linear relationship between the liquid level and the capacitor charging time. The main advantages of this developed system are linear input-output relationship, small in size, easily portable, cost effective, and independent on the ambient temperature effect. The system can also be exploited to measure dielectric constant of liquid or solid in various process industries.
Key words： timer IC555; liquid level measurement system; capacitor charging time; co-axial cylindrical capacitive transducer
CLD number： TH714.8 Document code： A
Article ID： 1674-8042（2016）04-0383-05 doi： 10.3969/j.issn.1674-8042-2016-04-013
References
［1］Mathews S C, Thattai K, Ramanathan P K, et al. Design and development of a simple and efficient low cost embedded liquid level measurement system. International Journal of Engineering and Technology, 2013, 5(2): 734-741.
［2］Musayev E, Karlik S E. A novel liquid level detection method and its implementation. Sensors and Actuators, A: Physical, 2003, 109(1/2): 21-24.
［3］Nakagawa T, Hyodo A, Kogo K, et al. Contactless liquid-level measurement with frequency-modulated millimeter wave through opaque container. IEEE Sensors Journal, 2013, 13 (3): 926-933.
［4］LU Gui-rong, CHEN Shu-yue. A capacitive liquid level sensor with four electrodes. In: Proceedings of 3rd IEEE international conference on computer science and information technology, ICCSIT, 2010, (4): 628-632.
［5］Bramanti M. A high sensitivity measuring technique for capacitive sensor transducer. IEEE Transactions on Industrial Electronics, 1990, 37(6): 584-586.
［6］Kostopoulos G K. Design and analysis monograms for pulse-width and frequency modulation using the 555 timer. IEEE Circuits and Systems Magazine, 1984, 6(2): 4-11.
［7］Antonio-Lopez J E, Sanchez-Mondragon J J, Likamwa P, et al. Fiber-optic sensor for liquid level measurement. Optics Letters, 2011, 36(17): 3425-3427.
［8］Ambrozinski L, Lisowski M, Stepinski T, et al. Permanently installed guided-waves based liquid level sensors for hermetically sealed tanks. In: Proceeding of the 11th European Conference on Non-Destructive Testing (ECNDT 2014), Prague, Czech Republic, 2014.
［9］WANG Jian-Neng, LUO Ching-Ying. Long-period fiber grating sensors for the measurement of liquid level and fluid-flow velocity. Sensors (Basel), 2012, 12(4): 4578-4593.
［10］YANG Hang-zhou, Sulaiman Wadi Harun. Environment-independent liquid level sensing based on fiber-optic displacement sensors. Microwave and Opticed Technology Letters, 2011, 53(11): 2451-2453.
［11］YANG Hang-zhou, QIAO Xue-Guang, CHONG Wu-yi. Optical fiber sensing of salinity and liquid level. IEEE Photonics Technology Letters, 2014, 26(17): 1742-1745.
基于液位测量系统的定时器的开发
Banajit Chakraborty, T K Maiti
（Department of Applied Electronics and Instrumentation Engineering, Netaji Subhash Engineering College, Kolkata 700152, India）
摘要:本文基于液位测量系统设计开发了定时器， 其中IC555用于不稳定模式。 使用数字存储振荡器（DSO）测量的定时器输出波形接通时间的脉冲宽度， 即电容器充电时间(TC)， 与同轴圆柱形电容换能器的电容成线形比例， 且该电容随着液位的变化而线性变化。 因此， 我们获得了电容器充电时间与液位的线性关系， 该设计的优点是输入-输出具有线性关系， 尺寸小， 便于携带， 成本低， 且不受环境温度影响， 它还可用于测量各种工业中液体或固体的介电常数。
关键词:定时器IC555； 液位测量系统； 电容器充电时间； 同轴圆柱形电容换能器
引用格式：Chakraborty B, Maiti T K. Development of timer based on liquid level measurement system. Journal of Measurement Science and Instrumentation, 2016, 7(4)： 383-387. ［doi： 10.3969／j.issn.1674-8042.2016-04-013］
[full text view]
