Oscillator Circuits
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A Wien bridge oscillator produces sine waves with very low distortion level. The Wien bridge oscillator produces zero phase shift at only one frequency (f = Vx t RC) which will be the oscillation frequency. Stable oscillation can occur only if the loop gain....
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In the circuit the frequency trimming component is arranged so that the voltage across it is in quadrature with the voltage V0 from the bridge so that as it is adjusted the attenuation of the bridge only changes a little, avoiding the need for a two gang....
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Transistor Q5 and the 1000 ohm resistor form the variable element needed for controlling the frequency of VCO by limiting the charging current flowing into the 0.15 timing capacitor according to the forward bias being applied to Q5. As the voltage on pins 2....
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Lamp LI stabilizes the loop gain at higher frequencies while the limiting action of R2, CRI, and CR2 prevents clipping at low frequencies and increases the frequency adjustment range from about 3:1 to greater than 10:1.
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The circuit uses two gates of a 7400 IC cross-connected to form an astable multivibrator driven by the 1-pulse per second output of the digital clock IC. The hee-haw circuit has a low frequency astable modulator added to make a self-contained European-type....
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Using a single chip LM324 can, with active R-C networks, reduce the size of a 3-phase waveform generator, and prove useful in compact and stable 3-phase inverters. One quarter of an LM324 is used as a Wien bridge oscillator generating a pure sinusoidal....
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A sidetone oscillator is a special audio astable multivibrator. Keying is accomplished oscillator that is turned on and off with the by applying a positive dc potential, developed transmitter. The oscillator is rf-driven and bat- from the rf signal, to the....
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One section of the MC10101 is connected as a 100 MHz crystal oscillator with the crystal in series with the feedback loop. The LC tank circuit tunes the 100 MHz harmonic of the crystal and may be used to calibrate the circuit to the exact frequency. A second....
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This circuit employs an adjustable resonant tank circuit which insures operation at the desired crystal overtone. Cl and LI form the resonant tank circuit, which with the values specified as a resonant frequency adjustable from approximately 50 MHz to 100....
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The crystal element in this circuit is connected directly between the base and ground. Capacitor Cl is used to improve the feedback due to the internal capacitances of the transistor. This capacitor should be mounted as close as possible to the case of the....
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The crystal is in a feedback circuit from collector to base. A trimmer capacitor in series shifts the point on the reactance curve where the crystal operates, thus providing a frequency trim..
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The crystal operates into a complex load at series resonance. Ll, Cl, and C2 balance the crystal at zero reactance. Capacitor Cl fine-tunes the center frequency..
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This circuit is often used by amateur radio operations, shortwave listeners, and other operators of shortwave receivers to calibrate the dial pointer. The oscillator operates at a fundamental frequency of 100 kHz, and the harmonics are used to locate points....
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L1C1 are selected to be resonant at a frequency below the desired crystal harmonic but above the crystal"s next lower odd harmonic. C2 should have a value of 30-70 pF, independent of the oscillation frequency. There is no requirement for any specific ratio....
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This circuit works well in the range of 50 kHz to 500 kHz. Slight component modifications are needed for higher frequency operation..
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The crystal is placed between the collector of the output stage and the base of the input stage. The frequency of oscillation can be set to a precise value with trimmer capacitor CI. The range of operation for this circuit is 500 kHz to 10 MHz..
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If the output is low, application of a negative-going pulse to the trigger input sets the flip-flop (Q goes low), drives the output high, and turns off 1. Capacitor C is then charged through Ra until the voltage across the capacitor reaches the threshold....
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Before power is applied, the input and output are at ground potential and capacitor C is discharged. On power-on, the output goes high (Vdd) and C charges through R until V is reached; the output then goes low (Vss). C is now discharged through R until Vn is....
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This dual astable multivibrator provides versatility not available with single timer circuits. The duty cycle can be adjusted from 5% to 95%. The two outputs provide two phase clock signals often required in digital systems..
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This circuit has a Schmitt trigger and integrator built around one op amp. Timing is controlled by the RC network. Voltage at the inverting input follows the RC charging exponential within the upper and lower hysteresis levels. By closing the switch SWI, the....
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Symmetry of the square-wave output is maintained by connecting the right side of R2 through resistor R3 to the output of the third amplifier stage. This changes the charging current to the capacitors in proportion to the setting of frequency-adjusting....
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This self-starting fixed frequency oscillator circuit gives excellent frequency stability. Rl and Cl comprise the frequency determining network while R2 provides the regenerative feedback. Diode Dl enhances the stability by compensating for the difference....
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With the component values shown, the oscillator has a frequency of 8 kHz. When an input signal is applied to the base of Ql the current flowing through Ql is varied, thus varying the time required to charge Cl. Due to the phase inversion in Ql the direction....
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This low-cost operational-amplifier circuit (A) generates four different functions with adjustable periods. For the components shown here, the period of the output waveforms is given by T = 4RC and T = 2RC. With switch SI in position A, VI is a triangular....
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To obtain a 1000:1 Sweep Range, the voltage across external resistors Ra and Rb must decrease to nearly zero. This requires that the highest voltage on control pin 8 exceed the voltage at the top of Ra and Rb by a few hundred millivolts. The circuit achieves....
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The output-pulse width from the circuit is a linear function of the input pulse"s height. You can set the circuit"s input threshold to discriminate against low-level pulses, while fixed components limit the circuit"s maximum output -pulse width. With a....
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For frequencies below 20 MHz, a fundamental-frequency crystal can be used and the resonant tank is no longer required. Also, at this lower frequency range the typical MECL 10,000 propagation delay of 2 ns becomes small compared to the period of....
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This low cost, crystal-controlled oscillator uses one TTL gate. Two factors ensure oscillator start-up: The connection of NAND gates G1, G2, and G3 into an unstable logic configuration and the high loop gain of the three inverters. Values of R1, R2, C1,....
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An on-board oscillator and a 17-stage divider compose IC1. By connecting a standard 3.58-MHz, television color-burst crystal as shown, an accurate source of 60-Hz squarewaves is generated at the IC"s output, pin 1. Those pulses are then fed to IC2, a 4024....
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The circuit is an inverter set up as a linear amplifier. Adding the· crystal and capacitors to the feedback path, we turn the amplifier into an oscillator and force it to oscillate at, or least very near, the crystal"s resonant frequency. Trimmer capacitor....
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A voltage-variable capacitance tuning diode is placed in series with the crystal feedback path. Changing the voltage on VR varies the luning diode capacitance and tunes the oscillator. The 510-KO resistor, R1, establishes a reference voltage for VR -ground....
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This unit is easily tunable and stable, consumes little power, and costs less than other types of oscillators tlmt operate at the same frequencies. This unusual combination of features is made possible by a design concept that includes operation of the....