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Crystal quartz oscillator circuit

Konusu 'Fm Verici Devreleri' forumundadır ve uydudoktoru tarafından 10 Temmuz 2011 başlatılmıştır.

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    Another great quartz crystal oscillator schematic with bb139, a 2-nd harmonic quartz crystal and one BF214 transistor. So, the Q quartz is half of the desired transmitter frequency, L1 has 24 turns, 0.08mm Ø built on a 455kHz carcase. L2 has 8-9 turns / 0.8mm Ø / 5mm Ø. This quartz oscillator circuit has a great frequency stability, I’ve build it.

    Crystal quartz circuit components


    R1 = 10K
    R2 = 100K
    R3 = 8.2K
    R4 = R6 = 820
    R5 = 15K
    C1 = 330nF
    C2 = 1nF
    C3 = 1.5pF
    C4 = 15pF
    C5 = 2.2nF
    C6 = 6 – 25pF trimmer
    C7 = 4.7pF
    D1 = BB139
    D2 = 5.6v zenner diode
    T = BF214
    Q = half frequency quartz crystal

    Crystal quartz oscillator circuit schematic

    oscosc1.jpg
     
    Son düzenleme: 21 Mayıs 2015
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    This quartz crystal oscillator circuit has greater stability than a parallel resonance circuit. It generates frequencies up to 30 MHz or even higher if you use BFR91 for T1, T2 transistors and reduce R1 … R2 values. The MOSFET buffer insulate the oscillator from any connected circuit.

    Quartz Crystal Oscillator Circuit Schematic
    [​IMG]
     
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    A very simple DIY crystal oscillator circuit which use a quartz for frequency stability and a good rf transistor. Use a 2-nd or 3-rd harmonic crystal, for example if you want 100MHz use a 50MHz or 33.3 MHz quartz or if you want use a 4-th harmonic crystal but the output rf voltage will be lower. The L coil has 5 turns 0.8mm Ø, 6mm Ø, 1 mm step, output at first turn from voltage plus. Use C4 for fine frequency adjustments.

    For a great frequency stability, this crystal oscillator circuit must use a good varicap diode (you can use BB139) and a good crystal too.

    DIY crystal oscillator circuit components

    R1 = 5.6K
    R2 = 3.3K
    R3 = 560Ω
    R4 = 33Ω
    R5 = 10K
    R6 = 100K
    C1 = C2 = 1nF
    C3 = 10 … 33pF
    C4 = 10 – 60pF trimmer
    C5 = 22pF
    C6 = 120pF
    C7 = 100nF
    D = BB139
    T = BF199
    Q = QUARTZ CRYSTAL 2-nd, 3-rd or 4-th harmonic

    Do-it-yourself Crystal Oscillator Circuit Schematic
    [​IMG]
     
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    Quartz Crystal Oscillator – Overview

    Quartz crystal oscillatoris a stable frequency generator using a Quartz Crystal as a resonator. In the crystal oscillator circuit, frequency stability is one of the most important references, which is a factor in the ability of various load conditions to provide a constant output frequency.

    Quartz crystal oscillatorused in Quartz Crystal is very small and thin section, or a quartz wafer is cut with two parallel surfaces metallised to create the necessary electrical connections. End of the oscillation frequency is strongly influenced by the physical size and thickness of a piece of quartz crystal. So it is a very important parameter to be strictly controlled and known as the “characteristic frequency” of the crystal. Alternatively, in other words, the size and shape determine the frequency or crystal cannot be used on any other frequency.

    [​IMG]
    Quartz Crystal Oscillator

    The uses of quartz crystal oscillators are intended to reduce or even eliminate the lowest levels of the factors that can affect the frequency stability. The factors that most often appear to affect the output frequency stability, among others, variations in load, temperature, and the change in DC power supply. Selections of the proper components are used in a resonant feedback circuit may also increase the level of frequency stability included the amplifier output. Of course still has the limitations of the RC and LC tank circuits normally.

    So a quartz crystal is the frequency determining device with a very high degree of stability that is generally used in some type of oscillator circuit known as aquartz crystal oscillator(XO).

    Quartz Crystal Oscillator in Use

    Colpitts Quartz Crystal Oscillator

    Quartz crystal oscillatorcircuit below should work on the frequency range 1.5 MHz to 8 MHz. A 30 pF of trimmer capacitor is used to adjust the frequency slightly toward the center frequency. 2N3904 transistor functioning as a buffer amplifier to function as a stabilizer frequency and increase the power output. This crystal oscillator circuit can be easily modified to change the frequency of RC components (R1, C1, and C2). Any changes can be monitored by a frequency counter.

    [​IMG]
    1.5 MHz-8 MHz Colpitts Oscillator Circuit with Quartz Crystal

    Pierce Quartz Crystal Oscillator
    The most simple crystal oscillator circuit is the Pierce oscillator. An FET is used as a amplifying device, as it has a high input resistance, the use of a fence 10M resistance. The crystal has a frequency of 2000 MHz, but a reasonable crystal can be used. 3.3 mH the RF choke provides a high impedance to alternating current load, while the passage of the drain current without the DC voltage drop (the choke had a resistance of 41Ω). The choke must be specially designed to maintain the desired inductance, while wearing DC, so make sure you use the choke is designed for the purpose. The impedance of the coil is then 41k of 2 MHz, which is sufficient amplification.

    [​IMG]
    2 MHz Pierce Oscillator Circuit with Quartz Crystal

    Thus, the examples of Quartz Crystal Oscillator Circuit in this usage may shed some light to understand the quartz crystal oscillator.
     
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