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university:courses:electronics:electronics-lab-8 [23 Mar 2017 16:10] – [Materials:] Doug Merceruniversity:courses:electronics:electronics-lab-8 [23 Aug 2019 12:53] – Antoniu Miclaus
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-====== Activity 8. Stabilized current source (BJT) ======+====== Activity: Stabilized current source (BJT) ======
  
 ===== Objective: ===== ===== Objective: =====
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 ===== Hardware Setup: ===== ===== Hardware Setup: =====
  
-The waveform generator should be configured for a 1 KHz triangle wave with 1.5 volt amplitude and 1.5V offset. The input of scope channel 2 (2+) is used to measure the stabilized output current at the collector of Q2.+{{:university:courses:electronics:bjt_stabilized_cs-bb.png|}} 
 + 
 +<WRAP centeralign> Figure 2 Stabilized current source Breadboard Circuit </WRAP> 
 + 
 +The waveform generator should be configured for a 1 KHz triangle wave with 3 volt amplitude peak-to-peak and 1.5V offset. The input of scope channel 2 (2+) is used to measure the stabilized output current at the collector of Q2.
  
 ===== Procedure: ===== ===== Procedure: =====
  
 The zero gain amplifier can be used to create a stabilized current source. Because the voltage seen at the collector of transistor Q<sub>1</sub> is now more constant with changes in the input supply voltage as represented by AWG1, it can be used as the base voltage of Q<sub>2</sub> to produce a much more constant current in transistor Q<sub>2</sub>. The zero gain amplifier can be used to create a stabilized current source. Because the voltage seen at the collector of transistor Q<sub>1</sub> is now more constant with changes in the input supply voltage as represented by AWG1, it can be used as the base voltage of Q<sub>2</sub> to produce a much more constant current in transistor Q<sub>2</sub>.
 +
 +<WRAP centeralign>{{:university:courses:electronics:bjt_stabilized_cs-wav.png?500|}}</WRAP>
 +
 +<WRAP centeralign> Figure 3 Q<sub>2</sub> collector voltage vs. W1 voltage </WRAP>
 +
 +<WRAP centeralign>{{:university:courses:electronics:bjt_stabilized_cs-wav2.png?500|}}</WRAP>
 +
 +<WRAP centeralign> Figure 4 Q<sub>2</sub> collector current vs. W1 voltage Scopy plot </WRAP>
  
 {{ :university:courses:electronics:a8_f2.png?500 |}} {{ :university:courses:electronics:a8_f2.png?500 |}}
  
-<WRAP centeralign> Figure 2 Q<sub>2</sub> collector current vs. W1 voltage </WRAP>+<WRAP centeralign> Figure 4 Q<sub>2</sub> collector current vs. W1 voltage Excel plot</WRAP> 
 + 
 +**Resources:** 
 +  * LTSpice files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/ltspice/stabil_csource_ltspice | stabil_csource_ltspice]]
  
 ===== Questions: ===== ===== Questions: =====
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 The output current has a narrow peak. How could multiple copies of the peaking current source be combined to produce a much wider, flatter peak?  The output current has a narrow peak. How could multiple copies of the peaking current source be combined to produce a much wider, flatter peak? 
 +
 +<WRAP round download>
 +**Resources:**
 +  * Fritzing files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/fritzing/bjt_stab_curr_source_bb | bjt_stab_curr_source_bb]]
 +  * LTspice files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/ltspice/bjt_stab_curr_source_ltspice | bjt_stab_curr_source_ltspice]]
 +</WRAP>
  
 **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]** **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]**
  
university/courses/electronics/electronics-lab-8.txt · Last modified: 25 Jun 2020 22:07 by 127.0.0.1

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