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... Typical value =560 Ω The purpose of the series resistor is to limit the current to the LED [pic] Figure showing Connection of decoder to seven segment display. CHAPTER THREE 3.1 CIRCUIT DIAGRAM [pic][pic] Circuit operation When the switch is closed and no capacitor is connected, the 555 timer begins to give pulses but the output of comparator gives an output of 12V. This inhibits counting by the BCD counter. When a capacitor is connected, voltage at the non inverting terminal goes low therefore enabling counting to take place. When a capacitor charges above 7.56V, the output of comparator is 12V. This stops the counting. The value displayed at the seven-segment display indicates the value of the capacitor. The value of the capacitor is held on the display even if the capacitor is removed until reset is pressed to 000.
DIGITAL CAPACITANCE METER.
At the present time, the accurate measurement of capacitance is usually done on a capacitance bridge. This is a slow process and requires a skilled operator since the bridge must be precisely balanced and accurately read. These requirements make the bridge method unsuitable for production testing or field maintenance purposes. Measuring systems that require no adjustment by the operator or any particular skill have generally lacked accuracy.
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| linguaggio |  | inglese |
| numero di parole |  | 4866 (ca. 13 pagine) |
| qualità del contenuto |  | N/A |
| livello di linguaggio |  | N/A |
| prezzo |  | gratis |
| bibliografia |  | 5 |
Sommario
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Anteprima della tesi: DIGITAL CAPACITANCE METER.
CHAPTER ONE 1.0 INTRODUCTION 1.1 Background At the present time, the accurate measurement of capacitance is usually done on a capacitance bridge. This is a slow process and requires a skilled operator since the bridge must be precisely balanced and accurately read. These requirements make the bridge method unsuitable for production testing or field maintenance purposes. Measuring systems that require no adjustment by the operator or any particular skill have generally lacked accuracy. Shortcomings of these methods are; • Tedious and slow since most of them use analog where deflection of a pointer is a function of the value of electrical quantity being measured. • Difficulty in balancing as in the case of bridge since the voltages under consideration may drift. • Error due to stray capacitance (imperfect insulation) and mutual inductance, which are effects of the components used in the instruments. • A CRO is expensive and out of reach of most technicians and provides graphic record of variations in the quantity being measured. Advantages of digital capacitance meter. 1. Easy readability 2. Great accuracy. 3. Better resolution and high sensitivity. 4. Automatic polarity and zeroing. 1.2 ...... Typical value =560 Ω The purpose of the series resistor is to limit the current to the LED [pic] Figure showing Connection of decoder to seven segment display. CHAPTER THREE 3.1 CIRCUIT DIAGRAM [pic][pic] Circuit operation When the switch is closed and no capacitor is connected, the 555 timer begins to give pulses but the output of comparator gives an output of 12V. This inhibits counting by the BCD counter. When a capacitor is connected, voltage at the non inverting terminal goes low therefore enabling counting to take place. When a capacitor charges above 7.56V, the output of comparator is 12V. This stops the counting. The value displayed at the seven-segment display indicates the value of the capacitor. The value of the capacitor is held on the display even if the capacitor is removed until reset is pressed to 000.
Tesi presente nelle categorie
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Ingegneria
/Electrotecnica
/Elettronica
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