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Piezo crystal op amp6/21/2023 ![]() ![]() Because these capacitors are part of the oscilloscopes acquisition system, that potential shows up on the oscilloscope screen. This expansion and contraction creates an electric potential in the capacitors. Ceramic is a piezoelectric material, and the vibrations caused by physical force you exert on your probe and/or scope cause the capacitors to physically expand and contract slightly. It’s worth noting that I had to smack the oscilloscope pretty stinking hard to get this strong of an effect.Ī hand-numbingly hard slap demonstrates the piezoelectric effect on the Keysight InfiniiVision 1000 X-SeriesĪ signal is showing up on the oscilloscope because designers use ceramic capacitors in both probes and in oscilloscope acquisition boards. Now, don’t panic, this is a behavior that every scope in existence exhibits. ![]() Alternatively, you may be able to forgo the probe all together and simply tap on a bare BNC or even the top of the chassis (like in Figure 2). Remember, you may have to put your oscilloscope into “Normal” trigger mode to keep the signal onscreen. You should then see a signal show up on your screen. Remove the probe’s grabber hat & tap the exposed probe tip on a hard surface.Set your trigger level slightly above your baseline signal.Zoom in vertically on your signal to a small voltage per division setting.Grab a standard 10:1 passive probe and connect it to your oscilloscope.What does the piezoelectric effect have to do with oscilloscopes? Try this and see for yourself: The piezoelectric effect and oscilloscopes Basically, the lattice stops being an electrically neutral structure and has a charge distribution.Īlternatively, you can apply a voltage to a crystalline structure and it will physically change the shape of the crystal – the “reverse piezoelectric effect.” This is especially useful if you want to generate or sense physical time-varying waves. But as it’s compressed, the positive and negative charges “squish” out to opposite ends and create a potential across the structure. In a normal, non-compressed state the 2D lattice is at equilibrium. But as soon as an external physical pressure distorts the crystal structure, there will be an imbalance of charge. Essentially, the positive and negative charges are all at a happy equilibrium. The molecular charges are arranged in an electrically neutral arrangement. In general, a material’s molecules form into crystals because that is its most stable state. Piezoelectric materials are crystalline substances that produce an electric potential when subjected to mechanical stress. Whether you are using a cheap oscilloscope or a high end oscilloscope, the piezoelectric effect is something to be aware of. Who knew that simply bumping an oscilloscope the wrong way could cause mystery signals to appear on the screen? What makes this happen? It occurs because the ceramic capacitors in the oscilloscope’s acquisition system act as a piezoelectric material. Although, our Keysight Oscilloscopes YouTube channel just broke 250 videos and we haven’t done it yet, so you never know.Īnyways, what could be such a big deal? As it turns out the topic is actually, well (sigh) shocking. I don’t know about you, but if I had made 982 videos, I’d probably have played that card already. Not because he’s highlighting an oscilloscope “problem,” but because after waiting for 982 videos, Dave thought this topic was finally worth using the word “shocking” as a pun. His latest video caught my eye “ EEVBlog #983 – A Shocking Oscilloscope Problem ”. What does the piezoelectric effect have to do with oscilloscopes? If you follow any of the electrical engineering YouTube channels, you’re likely familiar with Dave Jones & the EEVBlog. ![]()
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