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    • #8311
      LectronFan
      Moderator

      Hi all,

      When browsing through the circuits posted on this forum, I noticed we’ve forgotten the Wien Bridge oscillator !

      Time to gather our Lectron set and build one in a blink of an eye !

      Here’s the setup :

      Wien Bridge oscillator

      After pressing the switch, we hear a warm sounding low tone. This tone is a sine wave.

      You’d probably wonder how this works.

      Well, we have a 2-stage amplifier consisting of T1 & T2.

      The “Wien bridge” consists of the components R1-R4 and C1-C2.

      The output and the input of this amplifier is connected to this circuit, so oscillations occur.

      We will later get in detail about this circuit and also propose this circuit build with the modern transistors.

      Greetings

       

       

       

    • #8312
      LectronFan
      Moderator

      Hello everyone,

      This is the same circuit with the modern silicon transistors.

      To build this circuit, you’ll need a few more connection blocks then included with the base and expansion set.

      If you compare the 2 versions, you’ll see the advantage that the legacy transistors have : they have the bias resistor incorporated which saves a lot of connections.

      We also have used for R7 a 100K resistor instead of the 330K for biasing T1. Do you think the sound produced will be the same ?

      Try it out and compare the results !

      Greetings

      Wien bridge Si transistors

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