| Electronics > Beginners |
| Need help getting 2.4MHz piezo to oscillate at its resonate frequency |
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| MatCat:
Ok so I have been digging around and found that schematic on a patent which I am trying to get working. I tried this circuit with the following components: R1: 1K (Though I tried a 10K pot from 10k to the point of it blowing up) C1: 1.2nF L1: 8.2uH TD: 20mm Piezo with resonate frequency of 2.4MHz ~100KHz Q1: BU406 C2: I tried a few different values, 33nF, 1.2nF, 100nF, 10nF L2: 100nH C3: 4.7uF Also I am not using the bridge rectifier, I am feeding it 24V (rated voltage for the Piezo) from a bench power supply. As listed above with a 1k for R1 the circuit draws 23mA but does not oscillate. Can someone help me to figure out proper values to force oscillation? The full patent is located at https://patents.google.com/patent/US3989042 |
| brybot:
To fix your original circuit, if you choose to do so, I'd add some resistance to the base of your BJT, or drop the load resistor. Right now your transistor is turning on too hard for it's load. |
| MatCat:
I've given up on the original circuit as its better to have the circuit work as the resonate frequency instead of trying to carefully find it and tune it seperately. I just did some math based on RC and I changed out C1 for a 560pF and c2 with a 47nF, now instead of 23mA draw the circuit is drawing 1.1A and not oscillating, think R1 needs go up ;) BUT still no oscillation |
| MatCat:
man I dunno why this is so difficult, I have been scowering the web for a week on this now, there are 3 or 4 threads here on EEVBlog of others trying to get this to work and no one has ever succeeded, what magic are these $5 atomizers on ebay / amazon doing that no one on the forums can figure it out? :) I did buy one on Amazon to take apart but the damn thing was completely potted in PLASTIC and I was unable to get it apart without destroying the circuit beyond the ability to even reverse engineer it. |
| T3sl4co1l:
*Shrug*, if you can make an impedance plot, we could simulate it. Or if you want to set something up I can take a more in-depth look, send me one to play with or something. Tim |
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