Published:2009/6/25 2:24:00 Author:May
Circuit Notes
The drain of the JFET Miller oscillator is tuned to the resonant frequency of the crystal by an LO tank circuit. (View)
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Published:2009/6/25 2:23:00 Author:May
Circuit NotesThe CMOS IC directly drives 5 TTL loads from either of 2 buffered outputs. device operates to 10 MHz and is bipolar, MOS, and CMOS compatible. (View)
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Published:2009/6/25 2:20:00 Author:May
Circuit Notes
The pilot lamp limits current to prevent damage to the crystal. (View)
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Published:2009/6/25 2:20:00 Author:May
Circuit Notes
This circuit operates 10-40 ppm above series resonance. It is a good circuit design with good to very good frequency stability. (View)
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Published:2009/6/25 2:17:00 Author:May
Circuit Notes This circuit operates at or near series resonance. It has fair to poor circuit design with parasitics, touch to tune, and fair frequency stability. (View)
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Published:2009/6/25 2:14:00 Author:May
Circuit NotesThis circuit operates 30-200 ppm above series resonance. Physically simple, but analytically complex. It is inexpensive with fair frequency stability. (View)
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Published:2009/6/25 2:04:00 Author:May
Circuit Notes
International Crystal OF-1 LO oscillator circuit for fundamental-mode crystals. (View)
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Published:2009/6/25 2:03:00 Author:May
Circuit Notes
L1C1 are selected to be resonant at a frequency below the desired crystal harmonic but above the crystal's next lower odd har-monic. C2 should have a value of 30-70 pF, independent of the oscillation frequency.There is no requirement for any specific ratio of C1/C2, but practical harmonic circuits seem to work best when C1 is approximately 1-3 times the value of C2. Diodes Dl-D3 provide a simple regulated bias supply. The resistance of RI should be as high as possible, as it affects the crystal's in-circuit Q. (View)
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Published:2009/6/25 1:51:00 Author:May
Circuit NotesTwo different negative-coefficient capacitors change in capacitance to counteract or compensate are blended to produce the desired for the decrease in frequency of the normal AT-cut characteristics. (View)
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Published:2009/6/25 1:47:00 Author:May
Circuit Notes
This circuit has a frequency range of 0.5 MHz to 2.0 MHz. Frequency can be adjusted to a precise value with trimmer capacitor C2. The second NOR gate serves as an output buffer. (View)
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Published:2009/6/25 1:42:00 Author:May
Circuit NotesThis circuit uses a 74500 Schottky TTL gate; no inductors are required. (View)
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Published:2009/6/24 23:50:00 Author:May
In the miniature high-voltage dc generator, the input to the circuit, taken from a 12-Vdc power supply, is magnified to provide a 10,000-Vdc output causing a pulsating signal, of opposite polarity, to be induced in T1's secondary winding.
The pulsating dc output at the secondary winding of T1 (ranging from 800 to 1000 V) is applied to a 10-stage voltage-multiplier circuit, which consists of D1 through D10, and C3 through C12. The multiplier circuit increased the voltage 10 times, producing an output of up to 10,000 Vdc. The mul-tiplier accomplishes its task by charging the capacitors (C3 through C12); the output is a series ad-dition of the voltages on all the capacitors in the multiplier.
In order for the circuit to operate efficiently, the frequency of the square wave, and therefore the signal applied to the multiplier, must be considered. The output frequency of the oscillator (U1-a) is set by the combined values of R1, R5, and C1 (which with the values specified is approximately 15 kHz). Potentiometer R5 is used to fine tune the output frequency of the oscillator. The higher the frequency of the oscillator, the lower the capacitive reactance in the multiplier.
Light-emitting diode LED1 serves as an input-power indicator, and neon lamp NE1 indicates an output at the secondary of T1. A good way to get the maximum output at the multiplier is to connect an oscilloscope to the high-voltage output of the multiplier, via a high-voltage probe, and adjust potentiometer R5 for the maximum voltage output. (View)
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Published:2009/6/24 23:31:00 Author:May
Circuit NotesThis crystal-oscillator circuit uses crystal. (View)
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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 22:33:00 Author:May
Here, a 2N3904 E-B junction is used as a noise generator, reversed bias. C is chosen to pass the lowest-desired frequency components of the noise. (View)
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