Digital Potentiometer Research Articles

The Research of the New Digital Equivalent Inductor

To meet the requirements of scientific research personnel on wide range and high-precision variable inductor. The new digital inductor is based on the impedance converting circuit. The new active impedance converting circuit is formed by integration operational amplifiers, a small amount of resistance and capacitance. Through control of the switching circuit part line, thus producing the equivalent pure inductance. Experimental results show that using digital potentiometer and analog switches adjust circuit resistance to adjust the inductance value. So that digital equivalent inductance has certain advantages in the circuit experiment debugging and inductance adjustable electronic products.

Design and Implementation of High-Precision Digital Audio Equalizer Based on FPGA

By adjusting a variety of different frequency signals, equalizer compensates or optimizes system deficiencies, equalizer is used in voice, communication systems, mechanical vibration, fault diagnosis and many other fields. Traditional analog equalizer has low precision, phase nonlinearity and more distortion characteristics. On the basis of this, a new digital equalization algorithm that abandon the traditional single FIR filter implementation method is proposed, frequency division effect is achieved by multiple phase sub-band filter row and multi-channel digital potentiometer, so the cost of digital equalizer design and difficulty of implementation are reduced, and flexibility of digital equalizer settings on the real-time system is improved. In this paper, QuartusII is applied to functional simulation, and downloaded into the FPGA via JTAG interface to verify the correctness of the results.

Digital Control of Bonding Force for Gold Wire Bonding Machine

In order to digitally control the bonding force of a wire bonder precisely, this paper uses a DC solenoid as a force source, and by controlling the solenoid’s current, which causes the electromagnetic force, we can control the bonding force that capillary applies. The bonding force control system in this paper is composed of PC (Personal Computer) and hypogyny MCU (Micro Controller Unit), which communicate using a RS485 interface. The digital value of a given bonding force is given by the PC to the MCU. By comparing the sampling current of the solenoid, and through PID regulation, D/A converter of the digital potentiometer and the solenoid driver circuit, the half-closed loop control system of bonding force is accomplished. Tuning of the PID parameters is accomplished with fuzzy adaptive control theory and simulated by Matlab simulink. The control system is tested by comparing the desired bonding force and the force actually applied and examming the relationship between bonding quality and bonding force. DOI: http://dx.doi.org/10.11591/telkomnika.v11i3.2306

Controlled Envelopment of Magnetic Particles within Liposomes using a Custom-Built Multi-Layer Magnetic Microfluidic Device

Liposomes can be magnetically triggered to release chemicals by encasing magnetic particles in an organized and predetermined fashion (e.g. linear array). Here we demonstrate a controlled arrangement of magnetic particles within liposomes using a custom-built microfluidic device. The multi-layer magnetic microfluidic device consists of two thin bottom layers containing low-melting point (117° C) 52% In - 48% Sn solder and a third top layer devoted to the input of lipids and magnetic particles. The microchannels containing the solder are electrically isolated and arranged in a lattice pattern; the top layer contains one channel, which is wide enough to span this solder lattice. To facilitate installing the solder into the channels, we reduce the surface free energy by first injecting a solution of 3-mercaptopropyltrimethoxysilane in acetonitrile and allowing it to dry. By controlling the current in the solder lattice we can non-invasively corral magnetic particles contained in the top channel. To control the magnetic multi-layer microfluidic device, we are implementing a digital potentiometer (AD7151) using an Arduino (Mega 2560) microcontroller with analog inputs for connecting the potentiometers. An AD7151 can step through 64 different positions offering fine control of the current within the solder lattice. This digital potentiometer permits us to vary the current by changing the resistance electronically rather than manually as in a conventional analog potentiometer. This device can not only be used to assemble magnetic particles within the liposomes for potential in vivo delivery, but it can also be adapted to sort liposomes based on their magnetic content.

Study on the Automatic Positioning for Cable Insulation Failure Based on Digital Bridge Method

To against the problem of the difficult for indentifying the reflected wave of traveling wave and the need of plentiful practical experience and operation skills, this article focuses on designing and developing a digital cable insulation automatic fault locator. The instruments which can locate the fault without the data of length of the cable is based on the principle of HV bridge method and consist of bridge use for measuring cable length and bridge use for locating cable insulation fault. It can automatically improve voltage output of the high-voltage power through constant current detection circuit. To make sure the abilities of high accuracy,stability and fast for this instrument, This article introduces high-precision digital potentiometer, optical isolation and self-balancing bridge.The optical isolation between high and low pressure not only can achieve a complete electrical isolation,but also improve the anti-interference for the system. 

High-Power LED Constant Current Dimming Circuit Design

In this paper, an adjustable constant current circuit is designed by combining the digital potentiometer X9312 and the microcontroller 89C52. We first introduce the overall component and structure of the constant current dimming circuit which needs to be designed. Then, the hardware circuit design and the software design are discussed in detail. Based on the proposed design method, the manufacturing and the testing of the prototype machine are taken at last. The testing results are satisfactory, and meet the design requirement. The proposed design approach has won award in 2009 National Undergraduate Electronic Design Contest.

The System of Liquid Level Detection

The design is a ultrasonic level meter based on the PIC18F4520 micro chip. This ultrasonic level meter can be achieved in data is not lost when the power is down, making multi-function button to change the value, accurate measurement of liquid level. Closed loop fixed gain amplifier and the echo peak calibration signal amplification technology eliminates the phase shift error and the amplitude fluctuation error of the method, and digital potentiometers to achieve the system's automatic gain control, improve the quality of the echo signal. The effect of design is good, especially in sewage treatment, and oil storage tank system that can not contact measuring system have a strong value in use.

A 64-Channel Transmitter for Investigating Parallel Transmit MRI

Multiple channel radiofrequency (RF) transmitters are being used in magnetic resonance imaging to investigate a number of active research topics, including transmit SENSE and B(1) shimming. Presently, the cost and availability of multiple channel transmitters restricts their use to relatively few sites. This paper describes the development and testing of a relatively inexpensive transmit system that can be easily duplicated by users with a reasonable level of RF hardware design experience. The system described here consists of 64 channels, each with 100 W peak output level. The hardware is modular at the level of four channels, easily accommodating larger or smaller channel counts. Unique aspects of the system include the use of vector modulators to replace more complex IQ direct digital modulators, 100 W MOSFET RF amplifiers with partial microstrip matching networks, and the use of digital potentiometers to replace more complex and costly digital-to-analog converters to control the amplitude and phase of each channel. Although mainly designed for B(1) shimming, the system is capable of dynamic modulation necessary for transmit SENSE by replacing the digital potentiometers controlling the vector modulators with commercially available analog output boards. The system design is discussed in detail and bench and imaging data are shown, demonstrating the ability to perform phase and amplitude control for B(1) shimming as well as dynamic modulation for transmitting complex RF pulses.

Ultra-Wideband Low-Noise Amplifier

Abstract Ultra-Wideband (UWB) Low-Noise Amplifier (LNA) is an essential part of the digital TV and UWB signal processor, but what makes it hard to design is the comprehensive consideration of bandwidth, noise and gain control performance. A new solution of high performance amplifier with low-noise, UWB and direct current (DC) is presented (Fig.1), which is composed of a precision pre-amplifier with AD797, a stepped gain controller with VCA810 and a digital potentiometer, an eight-order Bessel low-pass filter with LC network, a zero-drift corrector with the digital compensation method. The test results (Tab 1-3 & Fig.6) show that the gain of amplifier can be adjusted from 0 to 80 dB by step, the fluctuation of the pass band from DC to 10 MHz is less than 0.87 dB, stop-band attenuation reaches -42 dB/2fc, the equivalent input noise voltage is less than 7.2 μVrms. This design successfully solves some high challenging contradictions, such as ultra-wideband and low-noise, stop-band attenuation and pass-band fluctuation, precise gain control and DC zero-drift correction.

The Study of Variable Sensitivity in Dual-Axis Tilt Sensor

This paper investigates a high-precision and wide range measurement dual-axis tilt sensor. A method to improve the tilt sensor's range is specially put forward. With the measurement tilt increases, the sensitivity of the tilt sensor decreases seriously. As a result, the tilt measurement range is restricted. A closed loop dual-axis measurement system which is mainly constructed by dual-axis acceleration sensor, microprocessor, and digital potentiometer is proposed to come over this problem. An intelligent judgment method is put forward to solve the variable sensitivity problem caused by the variable sensitivity issues. Finally, a real dual-axis tilt measurement system experimental platform is constructed, which achieves the sensitivity automatically adjustment. The experimental result shows that the system can improve the sensitivity and the measurement range greatly.

Hybrid modelling and emulation of mem‐systems

SUMMARYThe recently published memristor emulator is based on a digital potentiometer, which is controlled by a microprocessor according to a programmed algorithm. After completing the emulator with suitable mutators, it is possible to emulate also memcapacitors and meminductors. This paper describes a novel approach to the modelling and emulation of general mem‐systems without the necessity of utilizing a digital potentiometer and additional mutators. Copyright © 2011 John Wiley & Sons, Ltd.

Design and Implementation of the Control System for an ARM9-Based Biochemical Analyzer

The design and implementation of the control system of an ARM9-based biochemical analyzer was introduced in detail. The S3C2440, an ARM9-based MCU, was the core of the control system. Precision regulator circuit of light of the analyzer was designed to stabilize the voltage supply of the light source. Closed-loop motor positioning control technology and freely programmable CPLD stepper motor sub-circuit technology were used to precisely position the grating. And flexible gain control technology based on digital potentiometers was employed to solve the problem of signal regulation. Such core technical problems was solved in succession, it thereby improves the instrument's performance and function and provides a number of inexpensive high-quality products for domestic small and medium sized hospitals especially rural hospitals and promoted the establishment of those hospitals in consequence.

A Design of Amplifying Circuit Based on Pt Resistance Strain Pressure Sensor

This topic takes the miniature Pt resistance strain pressure sensor made by Institute of Electronics, Chinese Academy of Sciences, as the core sensing element, and designs corresponding high-precision, low cost, low power amplifying circuit so as to realize accurate detection of atmospheric pressure in time. In this topic, a new design of amplifying circuit is taken, which first connects the digital potentiometer to the bridge circuit to adjust its balance, and then amplifies the output signal of the bridge circuit once to ideal value. This design not only meets the requirement of measurement, but also is feasible and reduces the cost. At the same time, in order to improve the precision of the potentiometer adjusting the bridge balancing, paralleled resistances are creatively used beside the digital potentiometer and its influence to the bridge balance adjustment and the accuracy of the bridge measurement is analyzed in detail.

Modular system for data acquisition and control of experiments with digital output

In the present work, the design of an efficient, modular, and scalable data acquisition and control system is described. It consists of an array of microcontrollers and memories, which feed a single concentrating unit whose information can be accessed by means of a universal series bus (USB) interface to be processed later on. Signal levels can be controlled through a set of digital potentiometers. This system is ideal for experiments with a large number of digital outputs.

Análise da fluoretação da água de abastecimento público da zona urbana do município de Campo Grande (MS)

The objective of this study was to analyze the fluoride concentration on the water that flows of the tap in the urban area of the city of Campo Grande (MS). For the fluoride concentration analysis, it was collected water samples of 21 schools placed in the 7 sub districts of the city, in 3 different opportunities, was made by the specific electrode method (using an Orion 9609 BN combined fluoride measuring electrode, coupled with an Orion EA-940 digital potentiometer). The results showed that 63.5% of the water samples presented acceptable fluoride levels (between 0.60 and 0.80 ppm) and 36.5%, unacceptable levels. In relation to the condition of the collect places, 76.2% were considered appropriate and 23.8% were inappropriate.

Impedance Measurement With Sine-Fitting Algorithms Implemented in a DSP Portable Device

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The development and implementation of a digital-signal-processor (DSP)-based portable impedance-measurement instrument is described. The circuit sinewave stimulus is generated by the device using a direct digital synthesizer at the desired measurement frequency. The sine is applied to a reference impedance in series with the unknown impedance. Two analog-to-digital converters (ADCs) acquire multiple samples of the two sine voltages, which are transmitted to the DSP. Sine-fitting algorithms determine the sine amplitudes, phases, dc components, and frequency. With these values and the reference-impedance values, the unknown impedance amplitude and phase are determined. Amplifiers, which are included in the device, extend the ADCs' input range, while a digital potentiometer enables the adjustment of the reference impedance to improve accuracy. </para>

Interface circuit for resistive sensors utilizing digital potentiometers

In this paper an interface for resistive sensors in a bridge configuration is investigated. The interface utilizes digital potentiometers in order to implement an automatic calibration procedure for the bridge circuit offset. Such an approach facilitates the use of digital signal processing with high flexibility; advantageous in modern instrumentation systems. Commercial digital potentiometers have a very limited resistance range and therefore this method to overcome the discrete nominal resistance values was developed. The system was simulated mathematically and automatic calibration of the offset voltage was demonstrated with a prototype. An important additional advantage was an increase in resolution compared to a simple potentiometer circuit.

63.3: Automated System for Response Time Optimization and Flicker Reduction In LCD Manufacturing

In order to meet the important requirement of fast response time for LCD-TV applications, the so-called Response Time Compensation (RTC) technique has been widely used. Defining an optimum look-up table (LUT) is a key process step for the application of this technology, but deriving optimized table entries is difficult to do and historically has taken excessive time. Expanding on our algorithmic development work presented at SID'04, we have created a fully automated system for obtaining an optimal LUT. Without requiring any operator involvement, this system quickly and objectively measures the panel under test, calculates optimized LUT values, and programs those values into the panel's non-volatile memory. Additionally, a new flicker minimization algorithm has been developed and implemented in this same system by using a digital potentiometer to set Vcom. Using this system, it is possible to optimize panel parameters for all products in the production line, resulting in very uniform image quality for all LCD-TV panels in spite of variations in process conditions.

Automatic tuning and matching of a small multifrequency saddle coil at 4.7 T.

A new circuit design for automatically tuning and matching a saddle coil for small animal imaging is presented. This design allows working at (1)H, (19)F, and (3)He resonance frequencies in a 4.7 T spectrometer. It is based on a balanced circuit with commercial variable capacity diodes controlled by a computer using digital potentiometers. The change between two different frequencies can be accurately performed in a few seconds. System Q is compared, between 140-210 MHz, to the same coil tuned and matched with high Q variable capacitors. Differences lower than 5% were found with a loaded coil. The proposed design has initially been evaluated in (19)F and (1)H NMR images acquired with a five-tube phantom. An application is also shown for the acquisition of (3)He, (19)F, and (1)H lung images in a control rat.

Instrument for Automatic Measurement of the Parameters of Solar Elements

An automated instrument for measurement of the parameters of solar elements based on an IBM personal computer, a digital potentiometer, and V7-21A digital voltmeters is described. The instrument produces a programmed specification of the load impedance of the solar elements in the range 0.002–800 Ω, measurement of short-circuit currents up to 4 A, no-load voltages and the dark and light voltage-current characteristics as well as a calculation of the basic parameters of the solar elements with display of the results on a monitor and printer. The error of the measurements and of the calculation of the parameters of the solar elements is at most 0.4%.