12/9/2023 0 Comments Piezo disc elements projects![]() ![]() ![]() So what to people do? They go and stick this into the line input of their recorder, typical impedance 50k, or the plug-in-power mic input of their recorder, typical impedance about 7k, and they start to grouch that this damn thing sounds tinny. I’ve terminated mine in 3.9M because that’s what I had to hand. If that is 20Hz, since the impedance of the capacitor is 1/2 pifreq*C then you want that to be > 530k. You need to put this into a load which is higher than the impedance of the series capacitor at the lowest frequency of interest. Hence the reputation for poor bass performance….”Ī piezo element can be thought of as a sound-dependent voltage source in series with a large capacitance of about 15nF. If wired to a consumer plug-in-power microphone input of about 7 kilohms impedance, the result is a 1kHz high-pass filter. When wired to a normal 50 kilohm line input this forms a 200Hz high-pass filter, which eliminates the bass. The reason why these devices often sound tinny is because the piezo sensor presents its signal through a series capacitance which is small, typically 15nF or less. However, the main reason these have gotten a bad rap is that many people couple them into a standard audio load, which loses low frequencies. This will tend to lead to a peakiness at mid-frequencies, which is why I glue these to a magnet to try and spread this peak and make the coupling to the source better. The brass disc on which the element is glued is designed to resonate at the design frequency of 2-4kHz so that a large audio output is achieved with a small power input. The sound to voltage conversion isn’t noted for its high quality – most piezo contact mics are tuned speaker elements used in reverse. First of all though, why do these things sound rotten the way they are most commonly used? Two solutions are proposed – the cheap and cheerful FET buffer which probably meets all the requirements of 90% of users who are using the devices on outside structures, and the high performance version for those who want higher performance and lower noise. The pickup needs to work into a much higher impedance, typically 1 megohm or so. By their nature they can generate a lot of signal, but they cannot drive a 50 kilohm typical line input. The problem with piezo guitar pickups and contact mics is that they are not well matched to typical audio inputs. They seem to promise a lot, but easily sound rough as commonly applied. They seem to cause grief when used as contact mics. Constructed in series or parallel, they can be manufactured both in round and rectangular shape.Cheap, innocent looking piezo elements do okay as greetings cards sounders. > Bending elements can be constructed from piezo disks and plates within certain manufacturing limits. PI Ceramic offers the following standard products: Stack actuators have proven their high reliability in applications for the semiconductor industry and medical engineering. Application-specific end pieces can be manufactured on request. Possible designs are low-profile or spherical end pieces made of metal, ceramics, glass or sapphire. For overheating protection, the actuators can be equipped with temperature sensors.įor mechanical coupling of the actuators, specific end pieces (tips and bases) can be mounted. They are then suited for repeatable positioning with nanometer precision. Optionally the piezo actuators can be fitted with sensors to measure displacement. ![]() External soldering guides are used for the parallel operation of all layers. For each piezo element, different wires according to the AWG standard are used. Standard contacts for piezo actuators are 100 mm stranded wires or soldering points. These are then fitted with contact electrodes and an outer insulation layer of polymer material. Several piezo ceramic elements, such as disks or plates, are stacked and glued to stack actuators for a greater displacement. ![]()
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