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university:courses:electronics:electronics-lab-8 [24 Jul 2017 15:21]
Antoniu Miclaus change amplitude value to peak-peak
university:courses:electronics:electronics-lab-8 [25 Jun 2020 22:07] (current)
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-====== Activity ​8. Stabilized current source (BJT) ======+====== ActivityStabilized 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 3 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 ​Q<​sub>​2</​sub>​ collector current vs. W1 voltage </​WRAP>​+<WRAP centeralign>​ Figure ​Q<​sub>​2</​sub>​ collector current vs. W1 voltage ​Excel plot</​WRAP>​ 
 + 
 +**Resources:​** 
 +  * LTSpice files: [[downgit>​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: [[downgit>​education_tools/​tree/​master/​m2k/​fritzing/​bjt_stab_curr_source_bb | bjt_stab_curr_source_bb]]
 +  * LTspice files: [[downgit>​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-8.1500902517.txt.gz · Last modified: 24 Jul 2017 15:21 by Antoniu Miclaus