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university:courses:electronics:electronics-lab-4 [12 Jul 2019 12:46] – Link for the stairstep.csv file needed for BJT curve tracer Pop Andreea | university:courses:electronics:electronics-lab-4 [26 Jan 2021 15:32] – [For further reading on the Howland current source:] Doug Mercer | ||
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- | ====== Activity | + | ====== Activity: A BJT Curve Tracer ====== |
===== Objective: ===== | ===== Objective: ===== | ||
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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. | 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 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. | + | Now at this point set the amplitude to 2 V peak-to-peak |
- | In Signal Generator Channel 1 configure a triangle wave with an amplitude of 5V 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. | + | In Signal Generator Channel 1 configure a triangle wave with an amplitude of 5V peak-to-peak |
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<WRAP centeralign> | <WRAP centeralign> | ||
- | 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 |
===== Procedure: ===== | ===== Procedure: ===== | ||
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<WRAP round download> | <WRAP round download> | ||
** Lab Resources: | ** Lab Resources: | ||
- | * Fritzing files: [[ https:// | + | * Fritzing files: [[downgit>education_tools/ |
- | * LTSpice files: [[ https:// | + | * LTSpice files: [[downgit>education_tools/ |
- | * Stairstep signal: [[ https:// | + | * Stairstep signal: [[downgit>education_tools/ |
</ | </ | ||
==== For further reading on the Howland current source: ==== | ==== For further reading on the Howland current source: ==== | ||
- | [[http:// | + | [[adi>static/ |
- | + | ||
- | [[http:// | + | |
[[http:// | [[http:// |