Wiki

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
university:courses:electronics:electronics-lab-4 [05 Mar 2019 11:04]
Antoniu Miclaus [Alternative Method]
university:courses:electronics:electronics-lab-4 [26 Jan 2021 15:32] (current)
Doug Mercer [For further reading on the Howland current source:]
Line 1: Line 1:
-====== Activity ​4. A BJT Curve Tracer ======+====== ActivityA BJT Curve Tracer ======
  
 ===== Objective: ===== ===== Objective: =====
Line 27: Line 27:
 ===== Directions and Setup: ===== ===== Directions and Setup: =====
  
-Build the simple curve tracer circuit shown in figure ​1. The green boxes indicate where to connect the ADALM2000. Using the custom waveform editor in the Scopy AWG tool, construct a stair-step waveform with 5 levels. Be sure to reset so that you are starting with flat line at 0%. First set the type to constant. Then with start set to 0%, length set to 20% and offset set to -100% click on generate function. There should now be a line at -100% from 0 to 20%. Next change ​the start to 20% and the offset to -50% and then click on generate function again. There should now be a line at -50% from 20% to 40%. Next set the offset to +50% and the start to 60% and then click on generate function again. There should now be a line at 0% from 40% to 60% and a line at 50% from 60% to 80%. Finally set the offset to 100% and start to 80% and click on generate function one last time. There should now be a final line at 100% from 80% to 100%. Click on save and your new waveform should be in channel 2. Now at this point set the frequency to 40Hz, the amplitude to 2 V and the offset to 2.6 V. The waveform in the display should start at 0.6V and increase in 1 V increments to 4.6 V (0.6, 1.6, 2.6, 3.6, 4.6) Each step should ​be 5 mSec long for a total of 25 mSec. In AWG channel ​1 configure a triangle wave with an amplitude of 2.5 V and an offset of 2.5V (wave should swing from 0 to 5V). Set the frequency to 200 Hz ( 5 times the 40 Hz of channel 2). Comparing the waveforms in channel ​1 and channel ​2, the triangle wave in channel ​1 should go through one cycle from 0 to 5 V and back to zero during the time of one step in the waveform in channel ​2. It will probably be necessary to set the phase of channel ​1 to 90 degrees to make them line up in this way.+Build the simple curve tracer circuit shown in Figure ​1. The green boxes indicate where to connect the ADALM2000. Using the Scopy Signal Generator ​tool, in Channel 2  Buffer tab import ​the csv file for the stairstep signal needed. 
 +Now at this point set the amplitude to 2 V peak-to-peak ​and the offset to 2.6 V. The waveform in the display should start at 0.6V and increase in 1 V increments to 4.6 V (0.6, 1.6, 2.6, 3.6, 4.6). For each step to be 5 mSec long for a total of 25 mSec, set the sampling rate 200 Hz. 
 +In Signal Generator Channel ​1 configure a triangle wave with an amplitude of 5V peak-to-peak ​and an offset of 2.5V (wave should swing from 0 to 5V). Set the frequency to 200 Hz ( 5 times the 40 Hz of channel 2). Comparing the waveforms in Channel ​1 and Channel ​2, the triangle wave in Channel ​1 should go through one cycle from 0 to 5 V and back to zero during the time of one step in the waveform in Channel ​2. It will probably be necessary to set the phase of Channel ​1 to 90 degrees to make them line up in this way. 
  
-You should export your newly created stair-step waveform to a .csv file for future use. 
  
 ===== Procedure: ===== ===== Procedure: =====
Line 152: Line 153:
 <WRAP centeralign>​ Figure 15, Circuit to measure V<​sub>​BE</​sub>​ breadboard connection </​WRAP>​ <WRAP centeralign>​ Figure 15, Circuit to measure V<​sub>​BE</​sub>​ breadboard connection </​WRAP>​
  
-The generator output W1 should be configured for a 100 Hz triangle wave with 2 volt amplitude and -2 volt offset (for an NPN device). The single ended input of scope channel 2+ is used to measure the voltage at the base of the transistor (optionally connect 2- to the emitter to remove any input offset of the op-amp). The setup should be configured with channel 1 connected to display the output of W1 and channel 2 connected to display the base voltage. The emitter current is calculated as the voltage of W1 / 1KΩ.+The generator output W1 should be configured for a 100 Hz triangle wave with 2 volt amplitude ​peak-to-peak ​and -2 volt offset (for an NPN device). The single ended input of scope channel 2+ is used to measure the voltage at the base of the transistor (optionally connect 2- to the emitter to remove any input offset of the op-amp). The setup should be configured with channel 1 connected to display the output of W1 and channel 2 connected to display the base voltage. The emitter current is calculated as the voltage of W1 / 1KΩ.
  
 ===== Procedure: ===== ===== Procedure: =====
Line 213: Line 214:
 <WRAP round download>​ <WRAP round download>​
 ** Lab Resources:​** ** Lab Resources:​**
-  * Fritzing files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​fritzing/​bjt_curve_bb | bjt_curve_bb]] +  * Fritzing files: [[downgit>education_tools/​tree/​master/​m2k/​fritzing/​bjt_curve_bb | bjt_curve_bb]] 
-  * LTSpice files: [[ https://minhaskamal.github.io/DownGit/#/home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​ltspice/bjt_curve_ltspice ​bjt_curve_ltspice]]+  * LTSpice files: [[downgit>​education_tools/tree/master/m2k/ltspice/bjt_curve_ltspice | bjt_curve_ltspice]] 
 +  * Stairstep signal[[downgit>​education_tools/​blob/​master/​m2k/​import_waveforms/waveforms_sg/​stairstep.csv ​stairstep]]
 </​WRAP>​ </​WRAP>​
 ==== For further reading on the Howland current source: ==== ==== For further reading on the Howland current source: ====
  
-[[http://​www.cirrus.com/​en/​pubs/​whitePaper/​199210-Apex-Versatile_current_source_circuits.pdf|http://​www.cirrus.com/​en/​pubs/​whitePaper/​199210-Apex-Versatile_current_source_circuits.pdf]] +[[adi>static/​imported-files/​application_notes/​236037846AN_843.pdf|http://​www.analog.com/​static/​imported-files/​application_notes/​236037846AN_843.pdf]]
- +
-[[http://​www.analog.com/​static/​imported-files/​application_notes/​236037846AN_843.pdf|http://​www.analog.com/​static/​imported-files/​application_notes/​236037846AN_843.pdf]]+
  
 [[http://​michaelgellis.tripod.com/​howland.html|http://​michaelgellis.tripod.com/​howland.html]] [[http://​michaelgellis.tripod.com/​howland.html|http://​michaelgellis.tripod.com/​howland.html]]
university/courses/electronics/electronics-lab-4.1551780266.txt.gz · Last modified: 05 Mar 2019 11:04 by Antoniu Miclaus