Difference between revisions of "Lab 8 TF EIM"

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=Reverse current=
 
=Reverse current=
  
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#Construct the circuit below using a DC power supply, a diode.
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1.) Construct the circuit below using a DC power supply, a diode.
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# attach an Oscilloscope set to 1M<math>\Omega</math> input impedence as shown in the circuit diagram.  The oscilloscope will serve as a Resistor to measure the voltage across the diode and calculate the current.
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#Measure the diode reverse current <math>I_r</math> as a function of the DC supply voltage.
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[[File:Lab8_ReverseCurrentDiode.png|200 px]]
 +
 
 +
2.) Attach an Oscilloscope with internal resistance <math> R_{scope}= 1M\Omega</math>.  The scope will measure the voltage drop across R and thus the current will be given by this voltage difference divided by R.
 +
 
 +
3.) Determine a value for R which will allow you to measure a current of at least 10 mA  (prefeferably 50 mA) at the diodes reverse bias cut off voltage. Show your power calculation. (5 pnts)
 +
 
 +
 
 +
4.) Measure the diode reverse current <math>1 \mu A <  I_r < 40 mA</math> as a function of the DC supply voltage.
 +
 
 +
{| border="3"  cellpadding="20" cellspacing="0"
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| Bias Voltage || V_{scope} || Current (V/R) || Diode power || R power
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|-
 +
| ||  ||  || ||
 +
|-
 +
| ||  ||  ||  ||
 +
|-
 +
| ||  ||  ||  ||
 +
|-
 +
|}
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 +
 
 +
 
 +
5.) Fill in the blank.  The reverse biased diode act as a constant _______________ source.  (5 pnts)
  
 
=Forward Current=
 
=Forward Current=
−
#now swap the diode dirction and repeat the measurement in the previous section.
+
1.) now swap the diode direction and repeat the measurement in the previous section.
 +
 
 +
[[File:Lab8_ForwardCurrentDiode.png|200 px]]
 +
 
 +
2.) Attach an Oscilloscope with internal resistance <math> R_{scope}= 1M\Omega</math>.  The scope will measure the voltage drop across R and thus the current will be given by this voltage difference divided by R.
 +
 
 +
3.) Determine a value for R which will allow you to measure a current of at least 10 mA  (prefeferably 50 mA) at the diodes reverse bias cut off voltage.
 +
 
 +
 
 +
4.) Measure the diode forward current as a function of the DC supply voltage.
 +
 
 +
{| border="3"  cellpadding="20" cellspacing="0"
 +
| Bias Voltage || V_{scope} || Current (V/R) || Diode power || R power
 +
|-
 +
| ||  ||  ||  ||
 +
|-
 +
| ||  ||  ||  ||
 +
|-
 +
| ||  ||  ||  ||
 +
|-
 +
|}
 +
 
 +
 
 +
 
 +
5.) Fill in the blank.  The forward biased diode act as a constant _______________ source.  (5 pnts)
 +
 
 +
=Graph=
 +
#Plot the diode current (on the ordinate) versus the diode voltage (on the abscissa)for the forward and reverse biased diode on the same graph. (35 pnts)
  
 
=Questions=
 
=Questions=
  
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#The reverse biased diode acts like a constant ____________.  
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1.) Plot the reverse biased diode for voltages beyond the turn on voltage and measure the effective impedance of the diode using a linear fit. (20 pnts)
−
#The forward biased diode has a very __________ resistance.  A reverse biased diode has a very ____________ resistance.
+
 
−
#The approximate DC forward resistance for diode #___________ is _________ when the forward current is _______________.
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2.)The measured reverse biased turn on voltage is _________ Volts for silicon diode type # IN_____________.  The % difference between the measured turn on voltage and the one given in the specification is __________%.  Circle the correct answer in the parentheses.  This % difference (is / is not) within the measurement uncertainty. ( 10 pnts)
−
#The approximate DC reverse resistance for diode #___________ is _________ when the forward current is _______________.
+
 
−
#The silicon diode #___________ has an approximate turn on voltage of ___________.
+
3.) Plot the forward biased diode  and measure the effective impedance of the diode using a linear fit in the linear region at large bias voltages. ( 20 pnts)
 +
 
 +
 
 +
=Show and tell=
 +
 
 +
1.) Use a two channel oscilloscope in "x-y" mode to illustrate the V-vs-I curve to your instructor.
 +
 
 +
2.) Create a circuit to cause an LED to illuminate.
  
  
 
[[Forest_Electronic_Instrumentation_and_Measurement]]
 
[[Forest_Electronic_Instrumentation_and_Measurement]]

Latest revision as of 19:43, 26 February 2015

Lab 8 The Diode Objective: Measure the current-voltage curve of a silicon diode.

Reverse current

1.) Construct the circuit below using a DC power supply, a diode.

Lab8 ReverseCurrentDiode.png

2.) Attach an Oscilloscope with internal resistance [math] R_{scope}= 1M\Omega[/math]. The scope will measure the voltage drop across R and thus the current will be given by this voltage difference divided by R.

3.) Determine a value for R which will allow you to measure a current of at least 10 mA (prefeferably 50 mA) at the diodes reverse bias cut off voltage. Show your power calculation. (5 pnts)


4.) Measure the diode reverse current [math]1 \mu A \lt I_r \lt 40 mA[/math] as a function of the DC supply voltage.

Bias Voltage V_{scope} Current (V/R) Diode power R power


5.) Fill in the blank. The reverse biased diode act as a constant _______________ source. (5 pnts)

Forward Current

1.) now swap the diode direction and repeat the measurement in the previous section.

Lab8 ForwardCurrentDiode.png

2.) Attach an Oscilloscope with internal resistance [math] R_{scope}= 1M\Omega[/math]. The scope will measure the voltage drop across R and thus the current will be given by this voltage difference divided by R.

3.) Determine a value for R which will allow you to measure a current of at least 10 mA (prefeferably 50 mA) at the diodes reverse bias cut off voltage.


4.) Measure the diode forward current as a function of the DC supply voltage.

Bias Voltage V_{scope} Current (V/R) Diode power R power


5.) Fill in the blank. The forward biased diode act as a constant _______________ source. (5 pnts)

Graph

  1. Plot the diode current (on the ordinate) versus the diode voltage (on the abscissa)for the forward and reverse biased diode on the same graph. (35 pnts)

Questions

1.) Plot the reverse biased diode for voltages beyond the turn on voltage and measure the effective impedance of the diode using a linear fit. (20 pnts)

2.)The measured reverse biased turn on voltage is _________ Volts for silicon diode type # IN_____________. The % difference between the measured turn on voltage and the one given in the specification is __________%. Circle the correct answer in the parentheses. This % difference (is / is not) within the measurement uncertainty. ( 10 pnts)

3.) Plot the forward biased diode and measure the effective impedance of the diode using a linear fit in the linear region at large bias voltages. ( 20 pnts)


Show and tell

1.) Use a two channel oscilloscope in "x-y" mode to illustrate the V-vs-I curve to your instructor.

2.) Create a circuit to cause an LED to illuminate.


Forest_Electronic_Instrumentation_and_Measurement

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