Sensors & Transducers: Unit 1 Part 2

Que1.5. What are the  colorful advantages of transducers? 

Answer  1. Electrical modification and attenuation can be done  fluently and that to  with a static transducer device.  2. No moving mechanical  corridor are involved in the electrical systems.  thus there’s no question of mechanical wear and tear and gash and no  possibility of mechanical failure.  3. The electric or electronic system can be controlled with a  veritably small  electric power.  4. Electrical signal  attained from electrical transducer can be  fluently  reused(  substantially amplified) and brought to a  position suitable for affair  device which may be an  index or archivist.  5. With the  arrival of IC technology, the electronic systems have come  extremely small in size,  taking small space for their operation.   

Que1.6. Give the  colorful disadvantages of transducers. 

Answer  1. While designing the circuit the  goods of  geriatric and drifts of parameters  of active  factors must be considered. This makes the design  complicated.  2. The electrical transducer is  occasionally less  dependable than mechanical  type because of the ageing and drift of the active  factors.  3. Using negative feedback  fashion, the  delicacy of  dimension and  the stability of the system are  bettered, but all at the  expenditure of  increased circuit complexity,  further space, and obviously,  further cost.   

Que1.7. What are the factors to be considered while  opting   transducer? 

Answer  1. It should have high input impedance and low affair impedance, to avoid   lading effect.  2. It should have good resolution over is entire  favored range.  3. It must be  largely sensitive to asked  signal and asleep to unwanted  signal.  4. It should be  rather small in size.  5. It should be  suitable to work in  sharp  terrain.  6. It should be  suitable to  repel pressure, shocks,  climateetc.  7. It must have high degree of  delicacy and  repetition.  8. named transducer must be free from  crimes.   

Que1.8. What are the  operations of transducers in  colorful  fields? 

Answer  1. Electromagnetic  Antennas  ii. Hall- effect detectors  iii. Disk read and write heads  iv. glamorous charges.  2. Electromechanical  Accelerometers  ii. Pressure detectors  iii. Galvanometers  iv. LVDT  cargo cells  vi. Potentiometers.  3. Electrochemical  Hydrogen detectors  ii. Oxygen detectors  iii. pH  measures.  4. Electroacoustic  Speakers( Loudspeakers, earphones)  ii. Microphones  iii. Ultrasonic transceivers  iv. Piezoelectric chargers  Sonar  vi. Tactile transducers.  5. Photoelectric  LED  ii. Incandescent and fluorescent  lights  iii. Photovoltaic cells  iv. Ray diodes  Photoresistors( LDR)  vi. Phototransistors.  6. Thermoelectric  Thermistors  ii. Thermocouples  iii. RTD( Resistance temperature sensors).  7. Radioacoustic  Radio transmitters and receivers  ii. G- M tube( Geiger- Muller tube).  

Que1.9. What’s potentiometer? bandy about its working. 

Answer  1. A potentiometer or variable electrical resistance transducer is composed  of a sliding contact and a winding. The winding is made of  numerous turns of   line, wrapped around anon-conducting substrate.  2. Affair signals from such a device can be realized by assessing a known  voltage across the total resistance of the winding and by measuring the  affair voltage, which is commensurable to the bit of the distance the  contact point has moved along the winding.  3. Potentiometers can also be configured in a rotary form, with  multitudinous  total revolutions of the contact possible in a  spiral arrangement.  4. The affair from the sliding contact as it moves along the winding is  actually  separate; the resolution is limited by the number of turns per  unit distance.  5. The  lading  crimes associated with voltage- dividing circuits should be  considered in choosing a measuring device for the affair voltage.  6. During the  seeing operation, a voltage Vs is applied across the resistive  element. A voltage  separator circuit is formed when slider comes into  contact with the  line.  7. The affair voltage( VA) is measured as shown inFig.1.9.1. The affair  voltage is commensurable to the  relegation of the slider over the  line.  8. also the affair parameter  relegation is calibrated against the affair  voltageVA.  

Que1.13. Give the construction and working of LVDT for   relegation  dimension. 

Answer  Main features of construction  1. The motor consists of a primary winding P and two secondary  windings S1 and S2 crack on a spherical former( which is concave in  nature and contains the core).  2. Both the secondary windings have an equal number of turns, and we  place them on either side of primary winding.  3. The primary winding is connected to an AC source which produces a  flux in the air gap and voltages are  convinced in secondary windings.  4. A  portable soft iron core is placed inside the former and  relegation to  be measured is connected to the iron core.  5. The iron core is generally of high permeability which helps in reducing  harmonics and high  perceptivity of LVDT.  6. The LVDT is placed inside  pristine  sword  casing because it’ll  give  electrostatic and electromagnetic shielding.  7. The both the secondary windings are connected in such a way that  redounded affair is the difference between the voltages of two windings  as shown.  Principle of operation and working  1. As the primary is connected to an AC source so interspersing current and  voltages are produced in the secondary of the LVDT. The affair in  secondary S1 is e1 and in the secondary S2 is e2. So the  discriminational affair  is,  eout =  e1 – e2.(1.13.1)  2. Eq.(1.13.1) explains the principle of operation of LVDT.  3. Now three cases arise according to the  locales of core which explains  the working of LVDT  Case I When the core is at null position( for no  relegation)  i. When the core is at null position  also the flux linking with both the  secondary windings is equal so the  convinced emf is equal in both the  windings.  ii. So for no  relegation the value of affair eout is zero as e1 and e2 both  are equal. So it shows that no  relegation took place.  Case II When the core is moved to overhead of null position( For   relegation to the upward of reference point)  In this case the flux linking with secondary winding S1 is more as  compared to flux linking with S2. Due to this e1 will be more as that of e2.  Due to this affair voltage eout is positive.  Case III When the core is moved to  over of null position  for  relegation to the  downcast of the reference point)  In this case magnitude of e2 will be more as that of e1. Due to this affair  eout will be negative and shows the affair to  over of the reference  point.  

Que1.14. What are the advantages and disadvantages of LVDT  transducers? 

Answer  Advantages  1. High affair and high  perceptivity The LVDT gives a high affair  and a high  perceptivity.  2. Ruggedness These transducers can  generally tolerate high degree of  shock and  climate especially when the core is spring loaded without  any adverse  goods.  3. Low hysteresis LVDTs show a low hysteresis and hence  repetition  is excellent under all conditions.  4. Low power consumption utmost of LVDTs consume power which is   lower than 1W.  Disadvantages  1. fairly large  deportations are  needed for  perceptible  discriminational  affair.  2. They’re sensitive to  slapdash  glamorous  fields but shielding is possible. This  is done by  furnishing  glamorous   securities with longitudinal  places.  3. numerous a times, the transducer performance is affected by  climate.  4. The  entering instrument must be  named to operate on AC signals or  a demodulator network must be used if a DC affair is  needed.  5. The dynamic response is limited mechanically by the mass of the core  and electrically by the  frequence of applied voltage.

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