oscilator equivalent circuit

[root2hell]

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

 

[doraemon]

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.

 

[root2hell]

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

- - - Updated - - -

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

 

[root2hell]

still i didn,t get any oscillations.

 

[D.A.(Tony)Stewart]

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.

 

[root2hell]

Thanks SunnySkyguy for your reply but can u plz elaborate

- - - Updated - - -

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

 

[D.A.(Tony)Stewart]

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.

 

[root2hell]

i get this

- - - Updated - - -

using CDS4069UB i get this

 

[Borber]

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**