The resonances result from the electrical input The presence ofĮlectrical resonances and anti-resonances make the piezoelectric The impedance for a non-piezoelectric element (of the same shape andĭielectrical properties) is also shown in blue. For a (simple geometry) piezoelectricĮlement, the electrical impedance over a given frequency range will Impedance is defined as the voltage drop across an element divided by The difference stems from the coupling of electricalĮnergy input to mechanical motion output. Non-piezoelectric dielectric elements when driven at high-enoughįrequencies. It differs substantially from the impedance of The electrical impedance is a distinguishing characteristic for The following article covers some basics of impedance vs. If you can find the source of certain 'terms' used to describe piezoelectric crystal behaviour then we can try to interpret them for you. They are not including lower sub-harmonics which emit out the side of the crystal, and the driver amplifier is designed not to allow these out-of-band frequencies. This is equivalent to the "average resonant impedance". However the term "Fundamental Radial Resonance" refers to the center point between the peak resonant frequency and the peak anti-resonant frequency. I could not find the term "average resonant impedance", at least during the searches I did. For a given resonate frequency a small variation in frequency is allowed, with less output as you move further away from the center point of peak resonate output. It is a basic law of physics that the larger the crystal, the lower the resonate frequency. Damage would occur if the intensity of the signal was too strong, and/or the crystal gets too hot due to a lack of a heat sink or high ambient temperatures. The anti-resonant frequency consumes the most amount of current and produces the lowest output level possible. The resonant frequency consumes the least amount of current and produces the highest output level possible. This protects both the driver and the crystal from non-resonate frequencies and DC offset currents that can warp the crystal. Often the driver is custom made for a certain type of Piezoelectric crystal. Those for 1MHZ to 10MHZ ultra-sound are small rectangles epoxied to a resonant plate. These disc are about 1"/25mm in diameter. Those for audio and low frequency ultra-sound have a capacitance of about 150nF. Piezoelectric transducers have large capacitive values compared to other transducers. For the £150 for a timer of eBay, do I scrap the idea? Or, it would be a really useful tool for a clock and watch repairer so is it worth putting the time in and making this, which I'm willing to do providing I'm not going down an impossible or very difficult path.Piezoelectric transducers have several major issues from the driving circuits point of view:Ĭapacitance. The second job would then be allowing you to select the KNOWN beat from a menu and it displaying the error + or - from what it should be, a much easier value to work with as you can then adjust the watch to try and correct the error.Īny help appreciate. The first job would be just listening and capturing the average beat time. We are describing a beat as a tick or then a tock. Would this be possible with an arduino? Most watches beat at between 4-8 beats per minute. These are available reasonably from China, they are a very very basically a pickup microphone, listen to the tick tock and time it. I repair watches and make clocks and I've always wanted a timing machine. Hi, I'm very rust with arduino and micro controllers but did a good few projects a few years back including making a coin change machine and a few other bits ( Homemade 10p Coin Change Machine - arduino, ch-926 and cube - YouTube)
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