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oscilator equivalent circuit

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root2hell

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hi, i am using the crystal oscillator equivalent circuit but didn,t get any oscillations can anyone help me. oscillator.JPG
 

Hello!

So you plugged your crystal to a DC source?
You will never get it oscillate this way.
Try to plug it between the input and output of an inverter.

Dora.
 

could you plz help me how to do that.???

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i did like that but still didn,t get any oscillations.oscillator.JPG
 

Try CMOS with 1M feedback.

TTL won't work because the input and output levels are asymmetric and it won't self bias. Vin =1.3 while Vout averages around 2.5 or less for TTL.
 

Thanks SunnySkyguy for your reply but can u plz elaborate

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do you mean like thisoscillator.JPG but with this i didn,t get oscillation
 

7404 is a standard power (old) TTL inverter. It won't work since Iin low needs more current than 1k can deliver below 1.3V. Std TTL input is driving a low impedance for logic 0 below two Vbe drops (1.3) where <0.8 is valid.

CD4069 is one of many types of CMOS inverters with high impdance input, and input threshold adjusts to V/2 or whatever gives a 50% duty cycle as R feedback and input capacitance forms a low pass DC self bias.

also you should read up on how crystal oscillators work with shunt capacitance to tune to specified freq for a rated load cap like 15pf

Check lib. For CMOS.
 

i get thisosc output.JPG

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using CDS4069UB i get this osc output.JPGoscillator.JPG
 

If you are willing you will read this article dealing with design of oscillator you want. It has some practical advice an theoretical explanations:

**broken link removed**
 

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