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university:courses:electronics:comms-lab-peltz-osc [27 Mar 2017 17:12] – [Materials:] Doug Merceruniversity:courses:electronics:comms-lab-peltz-osc [25 Jun 2020 22:07] (current) – external edit 127.0.0.1
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 =====Directions:===== =====Directions:=====
  
-Build the Peltz oscillator circuit shown in figure 3 on your solder-less breadboard. The green squares indicate where to connect the Discovery module scope channels and power supply. Be sure to only turn on the power supply after you double check your wiring.+Build the Peltz oscillator circuit shown in figure 3 on your solder-less breadboard. The green squares indicate where to connect the ADALM2000 module scope channels and power supply. Be sure to only turn on the power supply after you double check your wiring.
  
 {{ :university:courses:electronics:apltz_f3.png?500 |}} {{ :university:courses:electronics:apltz_f3.png?500 |}}
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 Set both scope inputs to 200 mV/div and the time base to 1 uSec/div. Set the trigger on the rising edge of channel 1. Set both scope inputs to 200 mV/div and the time base to 1 uSec/div. Set the trigger on the rising edge of channel 1.
 +{{ :university:courses:electronics:apltz_bb.png? |}}
 +
 +<WRAP centeralign> Figure 4 Peltz oscillator circuit breadboard connections </WRAP>
  
 =====Procedure:===== =====Procedure:=====
  
 Turn on the -5V power supply. Observe the output waveform across the LC tank on scope channel 1. You can also observe the waveform seen at the emitters of Q<sub>1</sub> and Q<sub>2</sub> using scope channel 2.  Turn on the -5V power supply. Observe the output waveform across the LC tank on scope channel 1. You can also observe the waveform seen at the emitters of Q<sub>1</sub> and Q<sub>2</sub> using scope channel 2. 
 +{{ :university:courses:electronics:apltz_scopyshot.png? |}}
 +
 +<WRAP centeralign> Figure 5 Peltz oscillator circuit Scopy shot </WRAP>
  
 Notice that the output signal swings positive and negative around ground (0 V). Measure the frequency of the output waveform. Measure the peak to peak amplitude R<sub>2</sub> and R<sub>3</sub> replaced with shorts (i.e. 0 Ω). Compare this to the peak to peak amplitude you measure with R<sub>2</sub> and R<sub>3</sub> in the circuit. Try other values for R<sub>2</sub> and R<sub>3</sub>. Is there a practical upper limit to the values of R<sub>2</sub> and R<sub>3</sub> and the peak to peak amplitude? Does changing the value of R<sub>2</sub> and R<sub>3</sub> effect the oscillating frequency? If so why? Notice that the output signal swings positive and negative around ground (0 V). Measure the frequency of the output waveform. Measure the peak to peak amplitude R<sub>2</sub> and R<sub>3</sub> replaced with shorts (i.e. 0 Ω). Compare this to the peak to peak amplitude you measure with R<sub>2</sub> and R<sub>3</sub> in the circuit. Try other values for R<sub>2</sub> and R<sub>3</sub>. Is there a practical upper limit to the values of R<sub>2</sub> and R<sub>3</sub> and the peak to peak amplitude? Does changing the value of R<sub>2</sub> and R<sub>3</sub> effect the oscillating frequency? If so why?
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 Compare the shape of the output waveform with R<sub>2</sub> and R<sub>3</sub> as shorts vs with them set to various values. How does the shape change and why? Compare the shape of the output waveform with R<sub>2</sub> and R<sub>3</sub> as shorts vs with them set to various values. How does the shape change and why?
  
 +<WRAP round download>
 +**Resources:**
 +  * Fritzing files: [[downgit>education_tools/tree/master/m2k/fritzing/peltz_oscillator_bb | peltz_oscillator_bb]]
 +  * LTspice files: [[downgit>education_tools/tree/master/m2k/ltspice/peltz_oscillator_ltspice | peltz_oscillator_ltspice]]
 +</WRAP>
 =====Questions:===== =====Questions:=====
  
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 **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/comms-lab-peltz-osc.1490627569.txt.gz · Last modified: 27 Mar 2017 17:12 by Doug Mercer

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