I have attached a colpitt oscillator, which has quartz crystal in the feedback. When i tested the circuit without the crystal it is operating at the required frequency, but when I insert the crystal in the feedback loop it is oscillating.
I would like to know, what might be the possible resons behind this, please help me on this.
I am using overtone crystal. I am using a 5th overtone crystal.
For the load resistor I am using 100k.
Supply voltage is 3V.
I removed the inductor in series with the crystal as I dont need to pull the crystal. Hence i named it 0R. I will try using capacitor in parallel with the emitter resistor.
Meanwhile, I didnt undertsand the overdrive concept, can anyone expalin in detail about this concept.
At this frequency you will need about 200-300nH across the crystal terminals to resonate out the 5-7pF of holder capacitance for the crystal to operate as it should. Just make sure the inductor has a SRF higher than the frequency you want to use.