Questions about Crystal oscillator circuit؟؟

Discussion in 'General Electronics Chat' started by samy555, Aug 27, 2015.

  1. samy555

    Thread Starter Active Member

    May 24, 2010
    116
    3
    Hello
    I've download (using google) the TX-2B/RX-2B datasheets,
    [​IMG]

    Iwill focus on the crystal oscillator built around Q1:

    [​IMG]


    I have a toy car, the transmitter unit is working on 3 Volt. It's a replica for the circuit in the datasheets. Only difference in the values of the elements:

    [​IMG]

    For the last figure, the 40MHz crystal is connected between two different voltages; the 3V at the collector and the approx. 1.2V at the base. This voltage difference is making crystal to oscillate.

    Question1: Where this oscillating signal is fed, Is to base , collector or both?

    Question2: What is the function of C1? Is it doing a feedback from collector to Emitter?

    Question3: Is the above configuration a common emitter crystal oscillator?

    Question4: I built the circuit and measure the operating point (IC = 22mA, VCE = 2.5V), is this a good Q-point? 22mA be withdrawn from a 3V battery is a very big current. It will be voided battery quickly.

    Thank you for your patience to my many questions
     
    Last edited: Aug 27, 2015
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