Practical Electronics/Low Pass Filter

Low Pass Filter

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LR Network

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Plot three points above we have a graph   . From graph, we see voltage does not change with frequency on Low Frequency therefore LR network can be used as Low Pass Filter

RC Network

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Plot three points above we have a graph   . From graph, we see voltage does not change with frequency on Low Frequency therefore LR network can be used as Low Pass Filter

Summary

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In general

  1. Low Pass Filter can be constructed from the two networks LR or RC .
  2. Low Pass Filter has stable voltage does not change with frequency on Low Frequency
  3. Low pass filter can be expressed in a mathematical form of
 
T = RC for RC network
  for RL network