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university:courses:electronics:comms-lab-colpitts-osc [27 Mar 2017 17:11]
dmercer [Hardware Setup:]
university:courses:electronics:comms-lab-colpitts-osc [27 Mar 2019 12:07] (current)
amiclaus [Questions:] add ltspice files
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 =====Hardware Setup:===== =====Hardware Setup:=====
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 +<WRAP centeralign>​{{ :​university:​courses:​electronics:​colpitts_osc-bb.png|}}</​WRAP>​
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 +<WRAP centeralign>​ Figure 3 Colpitts Oscillator breadboard circuit</​WRAP>​
  
 The green squares indicate where to connect the ADALM2000module AWG, scope channels and power supplies. Be sure to only turn on the power supplies after you double check your wiring. The green squares indicate where to connect the ADALM2000module AWG, scope channels and power supplies. Be sure to only turn on the power supplies after you double check your wiring.
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 Having finished construction the Colpitts oscillator check that the circuit is oscillating correctly by turning on both the + and - 5 V power supplies and connecting one of the oscilloscope channels to the output terminal. It may be found that the value of R<​sub>​3</​sub>​ is fairly critical, producing either a large distorted waveform or an intermittent low or no output. To find the best value for R<​sub>​3</​sub>,​ it could be replaced by a 1 KΩ or 5 KΩ potentiometer for experimentation to find the value that gives the best wave shape and reliable amplitude. The optimal value for R<​sub>​3</​sub>​ may change depending on the resonate frequency. Having finished construction the Colpitts oscillator check that the circuit is oscillating correctly by turning on both the + and - 5 V power supplies and connecting one of the oscilloscope channels to the output terminal. It may be found that the value of R<​sub>​3</​sub>​ is fairly critical, producing either a large distorted waveform or an intermittent low or no output. To find the best value for R<​sub>​3</​sub>,​ it could be replaced by a 1 KΩ or 5 KΩ potentiometer for experimentation to find the value that gives the best wave shape and reliable amplitude. The optimal value for R<​sub>​3</​sub>​ may change depending on the resonate frequency.
 +
 +A plot example using R<​sub>​1</​sub>​=10KΩ,​ R<​sub>​2</​sub>​=1KΩ,​ C<​sub>​1</​sub>​=4.7nF,​ C<​sub>​2</​sub>​=1nF is presented in Figure 4.
 +
 +<WRAP centeralign>​{{ :​university:​courses:​electronics:​colpitts_osc-wav.png|}}</​WRAP>​
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 +<WRAP centeralign>​ Figure 4 Colpitts Oscillator breadboard plot</​WRAP>​
  
 =====Questions:​===== =====Questions:​=====
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 |50 uH|  |  | |50 uH|  |  |
 |100 uH|  |  | |100 uH|  |  |
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 +<WRAP round download>​
 +**Lab Resources:​**
 +  * Fritzing files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​fritzing/​colpitts_osc_bb | colpitts_osc_bb]]
 +  * LTspice files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​ltspice/​colpitts_osc_ltspice | colpitts_osc_ltspice]]
 +</​WRAP>​
  
 **For Further Reading:** **For Further Reading:**
university/courses/electronics/comms-lab-colpitts-osc.1490627464.txt.gz · Last modified: 27 Mar 2017 17:11 by dmercer