Published:2009/6/24 23:30:00 Author:May
Circuit Notes
The crystal operates into a complex load at series resonance. L1, C1, and C2 balance the crystal at zero reactance. Capacitor C1 fine-tunes the center frequency. Tank circuit L2, C3 doubles the output frequency the circuit operates as an FM oscillator-doubler. (View)
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Published:2009/6/24 23:18:00 Author:May
Circuit Notes
The large inductive phase shift of L1 is compensated for by C1. Overtone crystals have very narrow bandwidth; therefore, the trimmer has a smaller effect than for fundamental-mode operation. (View)
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Published:2009/6/24 23:13:00 Author:May
Circuit NotcsA typical Butler oscillator (20-100 MHz) uses an FET in the second stage; the circuit is not reliable with two bipolars. Sometimes two FETs are used. Frequency is determined by LC values. (View)
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Published:2009/6/24 23:06:00 Author:May
Circuit NotesThis circuit isolates the crystal from the dc base supply with an rf choke for better starting characteristics. (View)
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Published:2009/6/24 23:02:00 Author:May
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Published:2009/6/24 22:57:00 Author:May
Circuit NotesA Schmitt trigger provides good squaring of the output, sometimes eliminating the need for an extra output stage. (View)
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Published:2009/6/24 22:00:00 Author:May
This circuit uses two multipliers for integration-with-contro llable-time -constants in a feedback loop. R2 and R5 will be recognized in the AD534 voltage-to-current configuration; the currents are integrated in C1 and C3, and the voltages they develop are connected at high impedance in proper polarity to the X inputs of the next AD534. The frequency-control input, EY, varies the integrator gains, with a sensitivity of 100 Hz/V, and frequency error typically less than 0.1% of full scale from 0.1V to 10V (10 Hz to 1 kHz). C2 (proportional to C1 and C3), R3, R4 provide regenerative darnp-ing to start and maintain oscillation. Z1 and Z2 stabilize the amplitude at low distortion by degenera-tive damping above ±10V. (View)
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Published:2009/6/24 21:59:00 Author:May
A range of 10 Hz to 10 kHz is covered by this circuit. (View)
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Published:2009/6/24 21:52:00 Author:May
Two gates of a Quad 4093 are used in an astable multivibrator. C1 is a three-gang 365 pF variable capacitor with sections paralleled. S3 and S4 switch in optional extra capacitors. (View)
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Published:2009/6/24 21:50:00 Author:May
An 88-mH surplus telephone toroidal coil is used in a 1-kHz oscillator. Up to 8 V p-p into a high-Z load is available. THD is 0.9%. (View)
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Published:2009/6/24 21:48:00 Author:May
Two gates of the Quad 4093 are used to make an oscillator. RX can be from about 5 kΩ to around 10 MΩ. CX can be from about 10 pF to many μF, the limit being set by the leakage of the capacitor. Frequency is approximately 2.8/RXCX (R MΩ, Cmfd). (View)
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Published:2009/6/24 21:42:00 Author:May
Using a potentiometer and steering diodes, this 1.2-kHz oscillator will provide 1 to 99% duty cycle. Vary C1 to change frequency. (View)
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Published:2009/6/24 21:39:00 Author:May
For variable-frequency operation, R1 and R2 can be replaced by a dual potentiometer. (View)
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Published:2009/6/24 21:37:00 Author:May
A 1-kHz gated oscillator with no long turn-on cycle is shown. R2, R3, and D1 preset the voltage on tuning capacitor C1 to 1/3 of the supply voltage. (View)
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Published:2009/6/24 21:31:00 Author:May
The circuit shown has a frequency range of 2 Hz to 30 kHz. R2 is a linear or log potentiometer. (View)
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Published:2009/6/24 21:28:00 Author:May
Circuit NotesStable VXO using 6-or 8-MHz crystals uses a capacitor and an inductor to achieve frequency pulling on either side of series resonance. (View)
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Published:2009/6/24 21:25:00 Author:May
Circuit NotesThis simple and cheap crystal oscillator comprises one third of a 7404, four resistors and a crystal. The inverters are biased into their linear regions by RI to R4, and the crystal provides the feedback. Oscillation can only occur at the crystals fundamental frequency. (View)
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Published:2009/6/24 21:15:00 Author:May
This circuit uses a single potentiometer to tune a 300- to 3000-Hz range. A FET op amp is used at A1 and A2. The upper frequency limit is determined by the gain-bandwidth product of the op amps. (View)
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Published:2009/6/24 21:12:00 Author:May
Five basic types of LC oscillators are shown. The frequency can be changed by using the formula:where Leffective =equivalent inductance Ceffective =equivalent capacitance (View)
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Published:2009/6/24 21:07:00 Author:May
Using R1, R7, and D1 to preset C1 to one third of the supply voltage, this circuit avoids a longer first cycle period than subsequent cycles. (View)
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