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  1. #1
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    How do I connect / couple an oscillator to a bridge circuit

    I am trying to use a Colpitts oscillator followed by a common collector buffer to provide the sine wave to a bridge circuit (I plan to use the bridge to roughly measure a varying capacitor - C8). The output impedance of the oscillator and buffer is fairly low (if I have calculated it properly in LTSpice).

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    When I connect the bridge circuit directly to the oscillator (other side of the bridge is grounded) I think it shows that there is some significant loading of the buffer.

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    How can I overcome the loading effect and attach the buffer output to the bridge in a way that maximises the voltage across the bridge?

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  2. #2
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    Re: How do I connect / couple an oscillator to a bridge circuit

    Besides output impedance which might be sufficient, loaded large signal output swing is apparently insufficient. You need larger class A bias current and probably a bigger transistor than BFR93A.



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