Capacitance Meter Project
ABSTRACT
Capacitance measurement is of immense importance in the field of electronics. An instrument that measures capacitance to accuracy better than 0.5% has been improvised and rendered auto-ranging by means of an 89c51 circuit. The principle is that of a “direct” or fundamental principle of the time constant of the component. For e.g., the time taken to charge a capacitor to 50% of the applied voltage is given by
0.5 V = V (1- exp (-t/τ) )
The value of t is determined as 0.69314718τ. Knowing t by an uninterrupted time measurement on the processor, we can find the value of capacitance.
Applications:
* It is used for measuring capacitance which are used in almost all circuits. * This is very useful in laboratories.
Capacitance meter
Chapter 1
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INTRODUCTION TO CAPACITANCE METER
-------------------------------------------------
1.1 INTRODUCTION
An instrument that measures capacitance to accuracy better than 0.5% has been improvised and rendered auto-ranging by means of an 89c51 circuit. The principle is that of a “direct” or fundamental principle of the time constant of the component. Capacitance measurement finds importance for various applications. The present technique is a non-bridge fundamental time based measurement which is useful for capacitance measurement.
1.2 CIRCUIT DESCRIPTION
The Capacitance meter is based on the basic relation of charging time through a resistor and uses a simple dedicated micro controller 89C51, with built in program for the Job. The “transducer” which measures the capacitance is just the sensing of a bit of information relating to charging the capacitor to half the applied voltage, through a CMOS Gate. The property of a CMOS AND Gate that its threshold voltage is 50% of the supply voltage
Capacitance measurement is of immense importance in the field of electronics. An instrument that measures capacitance to accuracy better than 0.5% has been improvised and rendered auto-ranging by means of an 89c51 circuit. The principle is that of a “direct” or fundamental principle of the time constant of the component. For e.g., the time taken to charge a capacitor to 50% of the applied voltage is given by
0.5 V = V (1- exp (-t/τ) )
The value of t is determined as 0.69314718τ. Knowing t by an uninterrupted time measurement on the processor, we can find the value of capacitance.
Applications:
* It is used for measuring capacitance which are used in almost all circuits. * This is very useful in laboratories.
Capacitance meter
Chapter 1
-------------------------------------------------
INTRODUCTION TO CAPACITANCE METER
-------------------------------------------------
1.1 INTRODUCTION
An instrument that measures capacitance to accuracy better than 0.5% has been improvised and rendered auto-ranging by means of an 89c51 circuit. The principle is that of a “direct” or fundamental principle of the time constant of the component. Capacitance measurement finds importance for various applications. The present technique is a non-bridge fundamental time based measurement which is useful for capacitance measurement.
1.2 CIRCUIT DESCRIPTION
The Capacitance meter is based on the basic relation of charging time through a resistor and uses a simple dedicated micro controller 89C51, with built in program for the Job. The “transducer” which measures the capacitance is just the sensing of a bit of information relating to charging the capacitor to half the applied voltage, through a CMOS Gate. The property of a CMOS AND Gate that its threshold voltage is 50% of the supply voltage
Bibliography: 1. A.K.Rai, G. Patel and S.N.Murthy, “Microprocessor based grain measurement system”,Jl. Instrument Soc. of India, Vol.26(2) 2. The 8051 Microcontroller and embedded systems,Muhammad Ali Mazidi , Janice Gillispie Mazidi, Rolin D. McKinlay