Rangkaian Osilator Berbasis Kristal

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This is circuit for accurate time-base generation using the readily available 3.5795MHz crystal commonly used in telecommunication equipment. Crystal-based oscillator with divider IC chain or a similar circuit in the form of an ASIC is used for time-base generation. The 3.5795MHz crystal is used in conjunction with a CD4060-based crystal oscillator- cum-divider (IC1). The crystal frequency is divided by 512 by IC1, which is further divided by 7 by CD4017 (IC2). IC2 is reset as soon as its Q7 output goes high.

Skema rangkaian osilator berbasis kristal

Thus the crystal frequency is divided by 3584, giving the final output frequency of around 998.8 Hz. This frequency can be trimmed to exactly 1 kHz with the help of trimmer capacitor VC1 as shown in the figure. The 1kHz signal can be further divided using decade counters to generate the required time period. EFY lab note. To generate required gate for use in a frequency counter circuit, the final oscillator output needs to be followed by a toggle flip-flop. For example, a 1kHz clock, when applied to a toggle flip-flop will generate gates with 1-sec ‘on’ period and 1-sec ‘off’ period. This circuit is estimated to cost below Rs 50.

Rangkaian Kristal Tester

type='html'>Kristal Tester

In the world of electronics using crystal oscilator almost always in use. In the circuit below is a series to test the crystal. (Not measuring frequensy). With this circuit we could find out whether the crystal is still good or not. Test Clip to attach electrodes on crystal (foot), S1 in the press (On) then LED1 will light up if the crystal is still good. if you mendapa difficulties 2N356U transistors can be used with the type of transistor NTE123AP / PN100 / 2N3904.

Skema rangkaian kristal tester

The mechanism of this crystal tester is very simple. If a good crystal is connected to the test lead, the oscillator will work, and an AC signal will be generated at Q1 emitter. This AC signal will flow through capacitor C3 and trigger the Q2 to light the LED indicator. The diode 1N4148 provide the back path for the AC signal. If the crystal is bad, the oscillator won’t work, and there is only DC voltage level at Q1 emitter. This DC voltage level won’t trigger the Q2 transistor since the capacitor C3 block any DC signal. You can use any high gain high frequency transistor for this crystal tester circuit, in case you can’t find exact transistor series as shown in the schematic diagram.

OSILATOR KRISTAL

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Dengan menambahkan gerbang logika (IC TTL), sebuah rangkaian osilator kristal akan memberikan kinerja yang lebih baik

Ada dua jenis rangkaian osilator kristal yang biasa digunakan, yaitu
rangkaian resonansi seri dan resonansi parealel
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Rangkaian resonansi osilator kristal paralel

Gambar di atas memperlihatkan implementasi dari rangkaian resonansi osilator kristal paralel rangkaian ini di disain agar dapat memantapkan frekuensi yang dihasilkan oleh kristal. frekuensi yang di hasilkan oleh rangkaian resonansi paralel akan di balik fasanya sebesar 180 derajat oleh inverter 74As04. Resistor 4k7 berfungsi memberikan umpan balik agar frekuensi yang dihasilkan lebih stabil. Resistor 10K (potensio meter) untuk memberikan tegangan bias 74AS04.

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Rangkaian resonansi osilator kristal seri

Gambar di atas memperlihatkan implementasi dari rangkaian resonansi oscilator kristal seri rangkaian ini juga di disain agar dapat memantapkan frekuensi yang dihasilkan oleh kristal. frekuensi yang di hasilkan oleh rangkaian resonansi seri akan di balik fasanya sebesar 180 derajat oleh inverter 74As04 Resistor 330 berfungsi memberikan umpan balik dan tegangan bias 74AS04.

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Pada prakteknya rangkaian resonansi di atas tidak dapat bekerja dengan menggunakan 74HCT04. Hal ini di sebabkan karna teknologi gerbang logika HCT tidak mampu mengikuti kecepatan clock dari kristal. Agar rangkaian dapat bekerja dengan baik gunakan gerbang logika yang memiliki kecepatan yang cukup tinggi, misalnya 74LS04.