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问 我的一个项目用到如图的33MHz震荡器.但不知为什么开机时震荡频率老是只有10.8MHz,如果换晶体,则可能变了频率,但不时想要的33MHZ.但如果用起子碰一下输入端13脚,那么震荡频率就变了正常的33MHz了.

这是什么原因?请各位大虾指教.不胜感激! 答 1: 用该电路产生过24M的,没问题.33M,没试过. 答 2: 多谢回复频率低点是没有问题.我也试过,但用33MHZ就不行了.这是为什么啊? 答 3: 你用的是33MHZ三次泛音晶体，基波11MHZ。30MHZ以上基本是泛音晶体，这个电路只管基波，不好随便用的。 答 4: oldli好厉害.感谢你了!请问该用什么电路? 答 5: 采用晶体振荡再选频最好控制在6谐波内否则电路复杂。 答 6: 泛音晶体的缘故,建议使用三点式震荡电路 答 7: 感谢OLDLI, 我放狗的电路,大家看看能否用一个反相器实现?Introduction to Fundamental Crystal Oscillators 1 - 21 MHz
Crystal units manufactured by Quartslab Marketing Ltd for use over the frequency range 1 to 21 MHz use an AT cut quartz plate and operate in their fundamental mode. Crystal units may be specified for operation in either a series or parallel resonant condition. This operating condition should be correctly specified when ordering or the crystal unit will not operate on the correct frequency. TyPICally, over the frequency range of 1 - 21 MHz there may be between 2 and 15 kHz difference between the parallel resonant and series resonant conditions, the series resonant condition being lower in frequency.

If parallel resonance is required, it is necessary to specify a load capacitance for the Crystal. This capacitance is not related to any capacitance present in the crystals or the circuit but refers to the load capacitance used when crystals are measured in standard test sets. The preferred value of capacitance is 30 pF but crystals CAN be manufactured for other values.

These circuits are designed for non-critical adjustment and operation with easily available components. In each case, an output of at least 500 millivolts RMS is available across a load of 1000 ohms in parallel with 15 pF. The circuits are suitable for use with supply voltages from 5 to 10 volts DC. Over this voltage range frequency stabilities of 0.001% (10 ppm) should be achieved.

Please note that where no load capacitance is specified for fundamental crystals we supply them calibrated for a 30 pF load and although the circuit is shown as suitable for crystals at 0.95 MHz (950 kHz) we do not offer crystals below 1.5 MHz.




Series Resonant Circuit (see fig1)



R1, R2, R3, R4 See Below
C1, C2, C3, See Below
C4 0.01µF
C5 47pF
TR1 BC108 or similar
L1 Close wound with 37SWG enamelled wire on 7.62mm diameter former with Neosid F25 coil


Frequency of X1 MHz R1 R2 R3 R4 C1 C2 C3 L1
0.95 -1.65 68k 33k * 2.2k .0047mf 680 pF 680 pF 140 Turns
1.6 - 2.5 68k 33k * 2.2k .0047mf 680 pF 680 pF 65 Turns
2.5 - 4.0 68k 33k 560 ohm 1.5k .0047mf 220 pF 220 pF 65 Turns
4.0 - 6.0 15k 6.8k 560 ohm 1.5k .001mf 270 pF 270 pF 40 Turns
6.0 - 10.0 15k 6.8k 560 ohm 1.5k 150 pF 220 pF 220 pF 26 Turns
10.0 - 15.0 15k 6.8k 560 ohm 680 ohm 100 pF 220 pF 220 pF 16 Turns
15.0 - 21.0 15k 6.8k 560 ohm 680 ohm 100 pF 100 pF 100 pF 10 Turns
答 8: 并联基频振荡器Parallel Resonant Circuit





R1 100K
R2 33K
R3 See below
C1, C2, C3 See below
C4 . 01µF
C5 47pF
VC 60pF Trimmer
TR1 BC108 or similar


Frequency of X1 MHz R3 C1 C2 C3
0.95 -3.0 3.3k 220 pF 220 pF not used
3.0 - 6.0 3.3k 150 pF 150 pF 33 pF
6.0 - 10.0 2.2k 150 pF 150 pF 33 pF
10.0 - 18.0 1.2k 100 pF 100 pF not used
10.0 - 18.0 1.2k 100 pF 100 pF not used
18.0 - 21.0 680 ohm 68 pF 33 pF not used











答 9: 三泛音振荡器Introduction to Overtone Crystal Circuits

With overtone operation of crystals, the overtone frequency is not an exact multiple of the fundamental frequency and the circuit design must ensure that the crystal does in fact operate at the overtone frequency.

In order to be certain of correct operation, it is preferable to specify series resonant crystals, and to provide external circuit elements to prevent oscillation at the fundamental frequency. Where parallel resonant overtone crystals are required a load capacitance must be specified

On following pages circuits are shown for 3rd overtone crystals 15 to 65MHz and 5th overtone crystals 60 to 105 MHz operating in their series resonant mode. In both of these circuits with the crystal short circuited, the oscillator should operate at or near the required frequency. With the crystal in circuit L1 should be adjusted for either (a) minimum voltage across the crystal or (b) for the exact frequency required. Ideally, these two points would coincide but they rarely will due to the need for a manufacturing tolerance on crystal frequency.

If L1 is of incorrect size it is possible for the oscillator to operate on a different order of overtone, for this reason it is important to accurately check the output frequency.

Under no circumstances should a tuned circuit at the crystal overtone frequency be included in the collector circuit of TR1 as this configuration will result in oscillation not controlled by the crystal. However it is possible to include a tuned circuit at that point which is twice or three times the crystal frequency. It is then possible to extract from the collector the hARMonics of the crystal frequency.

Unless otherwise specified we supply 3rd overtone crystals between 21 and 60 MHz. 5th overtone between 60 and 126 MHz and 7th between 126 and 175 MHz.



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Third Overtone Oscillator Circuit





R1 10K
R2 4.7K
R3 470 Ohm
R4 560 Ohm
TR1 BF180 or similar
C1 C2, C3, C4, See Below
C5 0.001mF
L1 wound is on a 7.62 diameter former with Neosid F29 core


Frequency MHz C1 C2 C3 C4 L1
15 - 20 100 pF 100 pF 68 pF 33 pF 12 Turns 30SWG Close Wound  
20 - 26 100 pF 100 pF 68 pF 33 pF 8 Turns 30SWG Close Wound  
25 - 31 100 pF 68 pF 47 pF 33 pF 8 Turns 30SWG Close Wound  
30 - 43 100 pF 68 pF 47 pF 33 pF 6 Turns 30SWG Close Wound  
42 - 55 100 pF 68 pF 47 pF 33 pF 5 Turns 30SWG 6 mm long
48 - 65 68 pF 33 pF 15 pF 15 pF 5 Turns 30SWG 6 mm long













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答 10: 五泛音振荡器Fifth Overtone Oscillator Circuit





XL1 Ri L1
50-70 MHz 2.7 K 7 Turns 6mm long
60-85 MHz 2.7 K 5 Turns 5mm long
80-105 MHz 1.2 K 3 Turns 6mm long.

R2 470 ohm Cl l2pF
R3 330 ohm C2 18pF
R4 470 ohm C3 33pF
C4 1000 pF

VT1 8F180, SE1O1O or similar.

L1 Wound with 20 B & S enameiled wire on 7.62 mm diameter former with Neosid F29 Core.

Under no circumstances should a tuned circuit at the crystal overtone frequency be included in the collector circuit of VT1, as this configuration will result in oscillation not controlled by the crystal.  答 11: 高至200MHZ的泛音振荡器OVERTONE CRYSTAL OSCILLATOR FOR UP TO 200 MHz






Frequency C1 C2 Ic (mA) RE (Ohms) RL (Ohms) Lp (mH)
75 8 pF 100 pF 25 510 470 0.25
120 8 pF 50 pF 25 390 300 0.1
150 5 pF 25 pF 5 1.1k 600 0.08
200 3 pF 20 pF 5 1.1k 600 0.05









The above diagram shows a true series resonant oscillator circuit suitable for use up to 200 MHz

It is recommended that transistors for use in this circuit have a high DC gain (HFE) and a low base resistance (RBB). Also ensure that the transit frequency is at least ten times that of the oscillator frequency.
答 12: 在12脚并上一个串联LC电路到地.LC的谐振频率刚好等于基波频率. 答 13: 去买个基频是33M的！能买到的；问题轻松解决；我买过30M的；33M的难买但是有；去问问；搞选频就麻烦了；会死人的； 答 14: 谢谢楼上两位我刚试过znh406的方法,但能搞出55MHZ的,33MHZ就是出不了.我用的是FM收音机的本振中频10.7MHZ陷波线圈电容.