# Crystal Oscillator Design and "Crystal Drive Level"

I followed the video at the link http://www.analogzoo.com/2015/07/ . The video directs watchers to a tool at http://www.analogzoo.com/lab/pierce_bjt.html to help determine parameters to cause resonation/clock generation.

I watched the video a few times and added appropriate parameters in the tool to get a Crystal Load Capacitance, Crystal Loaded Q, and Gain Margin in spec with what the video describes.

I match my Crystal Load Capacitance to my crystal of 12pf. I have a Q of about 87 and a Gain of about 5. If I built the circuit, I would think it would resonate.

Everything looks good, yet, my Crystal Drive Level is at 0uw.

Does this matter? I understand this to be the power consumed by the crystal and that too much can damage the crystal. Having 0 is probably a good thing. I am wondering about that. I have 5 Volts supplied. 2.5 peak to peak, c1 and c2 = 182pf, etc,

If I built this circuit, what lines show resonation? I am expecting to put my oscilloscope to ground and the line (on the right side) between the amplifier and the crystal. I would expect it to oscillate about 6.4 Mhz.

If I do this, I then would wish to put some counters to divide the clock a few times and see the division on my scope. Should adding additional ICs to divide the clock couse the clock to change much?

Thanks, Jeff

• Zero power means it won't work. The crystal needs a power > 0 to oscillate. How did you measure/calculate the power? I would get rid of the oscilloscope questions because they are watering down the important main subject. Jul 28 '17 at 14:24
• Thanks, I edited the question. In the video, the person explains that ideally an AC current probe would be used. Then he then describes a few equations that could approximate it. I imagine those equations are embedded in the web tool he wrote, and I used, to get at power. I was jiggling parameters in the web tool to get values that he suggests would cause oscillation, yet, power came out to 0. Thanks. The person in the video did not mention that power also had to be greater than 0, that makes sense though. Jul 28 '17 at 15:55
• Using this tool, can anyone offer suggestions on how to increase Crystal Drive Level. I am using a crystal where it can max out at 1 mw. I would like to get it the outputs of the web site about 600uw. Using this tool.... analogzoo.com/lab/pierce_bjt.html ... I have the parameters.. Vcc 5v, R1 56k, r2 27k, r4 3.9k, r3 1.5k, 300 for the frequency of the 2n3904, C1 and C2 both 182 pf, c3 10pf, c0 7pf, esr 40, frequency 6.5536 of crystall, 2.5 peak to peak, hit calc, crystal drive level is 0, I owuld like to drive the crystal with 5 volts if possible, .. what drives cdl? thks Jul 28 '17 at 16:55
• C1 and C2 at 182pF are AWFULLY HIGH!. This kills all gain at crystal frequency. Try something like 24 pF for a 12-pF crystal. Jul 28 '17 at 17:04
• Zero power, I suspect means it doesn't oscillate. The other thing is that most people would use an inverter and not a transistor amplifier with all the knock on component count. Jul 28 '17 at 18:22