It would already be cool if you can point me to some technics to calculate if the circuit is compatible (regarding the impedance, voltage and current levels). Can you maybe help figuring out if I can use this circuit with my equipment? It would be cool to be able to plug it into the most common inputs. For example, I use a piezo of type 717770, which has a impedance of 800 ohms, but I thought that piezos usually have a very high output impedancy? Also, I don't know if the circuit is compatible with 'normal' line-ins, for example my ax-390 amplifier or a common notebook mic input (in my case, a t400). But I don't know if it will actually work with my piezo and my power-amp/recording tool (sorry, I'm a noob in calculating electronical compatibilitys). Now I want to go with the circuit described in the link. I already tried buillding something like this with a mpf102, and it worked (a bit), but it only worked on a guitar amplifier, has no overvoltage safety, and I had the fear of breaking my equipment when plugging it in. Price for a QFN packaged device is USD 0.98 (3 000 pcs).I'm interested in building a preamp for a piezo contact mic like. The MAS6250 is available in QFN-16 3x3x0.75 mm package. When not used the device enters shut down operating mode (typ 0.11uA) to save power. The LED current is adjustable by external resistor. The LED driver supports use of pulse-width modulation (PWM) dimming control and is capable of driving up to 15mA current. The noise stuff is surprising I’d initially thought these were going to be like condenser mic capsules, with a low capacity at AF of a few tens of picofarads.They’re no such thing I’ve just measured a 35mm piezo disc on an LCR bridge, it comes in at a massive 28. In addition to multi-tone sound the device supports single-tone sound which frequency is adjustable by external resistor. The bridge-tied load (BTL) output of the piezo driver is capable of driving up to 35Vpp signal in a very wide supply voltage range from 1.2V to 5.5V. The output voltage is regulated and adjustable up to 17.5V by external resistors.
The heart of the IC is a high efficiency synchronous boost DC/DC converter requiring only a small 0806 sized 2.2mH inductor. The MAS6250 includes LED driver which offers additional area and cost saving in many applications using LEDs. Typical applications include piezo buzzers, various alarm products, white goods and handheld or portable devices with sound feature.
It is a high efficiency, easy to use and low cost solution for piezo sound applications requiring high sound pressure level (SPL). Micro Analog Systems Oy introduces combined piezo and LED driver IC in a small QFN-16 3x3x0.75 mm package. MAS6250 – Piezo and LED Driver IC for Multi-Tone Sound