Accelerometers can be used in meters to measure acceleration (rate of change over time) and measurement of inclination (inclination between the longitudinal axis of the object and the perpendicular to the plane tangential to the Earth's surface). Tilt measurements can be viewed as "direct current" or steady state measurements. In theory, the acceleration can be steady-state, but in practical applications, acceleration is usually a short-term temporary phenomenon. In a non-tilted application (short-time acceleration), a piezoelectric detector or a piezoelectric film sensor can be used as the sensor. Any type of piezoelectric sensor has an AC voltage source equivalent circuit in series with the capacitor (plus other reactive components that produce a second-order effect, which are not analyzed here). Typical values ​​are a few hundred picofarads to a few nanofarads. The capacitive coupling of the voltage source is why the device does not provide steady-state tilt measurements. The equivalent capacitance mentioned above, plus the shunt resistor of the input or subsequent amplification or snubber circuit, constitutes a single-pole high-pass filter (HPF). In the best case, the larger the shunt resistance, the longer the time constant of the pole in the high-pass filter. This means that the acceleration can be measured for a longer time before the time constant effect weakens the measurement. From a practical point of view (taking into account the usability of the device), a resistance of 1 GΩ can be selected. Due to the large value of this resistor, the amplifier used must have a very low bias or leakage current, preferably up to 1 pA. Figure 1 is a circuit diagram of a practical circuit. The piezoelectric film sensor is device X1. In the prototype design, the measurement-specific LDTM-028K device was used. One end of this sensor has been applied with a small amount of gravity, and adding a large amount of gravity at this end can increase the sensitivity. The sensor is connected to the non-inverting input of the op amp U1 via R1. R1 prevents overvoltage from damaging the input of the op amp. This is most likely to happen if the sensor is subjected to very high accelerations (such as a heavy blow). R1 can also be used to reduce the amplitude of the signal from X1. R1 in this circuit is 1GΩ. R2 is the input shunt resistor. The leakage current of 1pA flows through R2, which is also 1GΩ, which produces a bias voltage of 1mV (applied to the actual bias voltage of the op amp). R2 is connected to a reference voltage of 2.5V to set the quiescent output voltage of the op amp. The op amp is the ISL28158 (or any other device with ultra-low input bias/leakage current). The op amp is powered from a +5V DC supply. The DC gain is set by R3 and R4 and is +2V/V in this circuit. A 1μF capacitor (C3) forms a low-pass filter that reduces the response of the circuit to higher frequency vibrations. Film capacitors are preferred here because ceramic capacitors may introduce additional annoying piezoelectric effects (also known as the howling effect). If additional low-pass filtering is required, an additional pole can be added at the output of the op amp, R5 and C4 in the figure. Mount the X1 on the board so that gravity is applied to the underside of the board and the sensor bends in the direction of the acceleration to be measured. Applause for Obelisk 65, the palm-fit tech-chic gathers GEEKVAPE's most cutting-edge technology. geekvape obelisk series box mod,geekvape obelisk series pod kit,geekvape obelisk series vape kit,geekvape obelisk series mods,geekvape obelisk series disposable Ningbo Autrends International Trade Co.,Ltd. , https://www.ecigarettevapepods.com
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