A Modified Impedance-Frequency Converter for Inexpensive Inductive and Resistive Sensor Applications

Abstract

In this paper an exceptionally simple transducer is presented that is developed for experimental and custom-made sensors with inductive or resistive impedance output. It is based on a venerable 555 Integrated Circuit in a modified astable configuration. Due to single supply 5 V operation, it is directly compatible with most modern microcontroller systems, such as the popular Arduino platform. Various exemplary sensor characteristics are presented, including displacement, force, magnetic field, temperature and light sensing applications. While the transducer is not designed for high accuracy, it allows for fast and inexpensive application of various experimental sensors, such as magnetoelastic or GMI (Giant Magneto Impedance) sensors.

New Insights towards High-Temperature Ethanol-Sensing Mechanism of ZnO-Based Chemiresistors

“…Reports dedicated to the detection of EtOH or MeCHO on chemiresistors operating in ac-mode are rare. Certain conceptual approaches to the impedance measurement of sensors are discussed in [24]. In [25], the authors report the detection of ethanol vapours at a concentration of 0.7-5.0 ppm on ZnO nanorods at a working temperature of approximately 400 • C. The nanorods were grown via a hydrothermal route directly on a multielectrode chip.…”

Novel Giant Magnetoimpedance Magnetic Field Sensor

“…Some have been based on microprocessor processing of the characteristics, mainly on the linear part of the impedance curve. The computational capabilities of the microprocessors of that time were small when compared to current solutions, which is why the prototype designs of GMI sensors were based mainly on analog electronics [10,18,[29][30][31]. A quasi-linear relationship occurs for a double-peak curve between the zero magnetizing field and the anisotropy field.…”

A Highly Robust Interface Circuit for Resistive Sensors

“…In contrast, quasi-digital converters, i.e., resistance-to-frequency [5,6], -period [7,8] or -duty-cycle [9] converters, are preferred if the resistance variations are very large. This converters not only provide a wider dynamic range but also simplify interfacing to digital systems, as no analog-to-digital converters (ADCs) are required [10,11]. In this way, the resistance is measured indirectly using a simple digital counter.…”