Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com has links to 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.

HOME Schematics Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches
Welcome to DiscoverCircuits.com - online since 2002

See Media Kit for
Advertising Opportunities

Attention Designers:  Please alert us by eMail if we have linked to sites
where your original material has been copied without your permission.
We will change to the LINK to your site.  
Thank you.

 


Math Function: Logarithmic
Math Functions Main Page 
 

Last Updated: October 24, 2017 02:55 PM


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

A Collection of Extended Math Subroutines for the MAX7651 -  App Note/ 958 / Aug-03__ Maxim Integrated

A primer on binary-arithmetic rounding -  01/21/99 EDN-Design Ideas -    (Scroll to find this one)  As digital communications and data compression/decompression proliferate, signal-processing functions grow in importance.     __ Circuit Design by Tom Balph, Motorola SPS, Tempe, AZ

Algorithm Generates Random Signal -  12/05/96 EDN-Design Ideas - A common way to simulate a sequence of bandwidth-limited-noise samples is to start with a sequence of uncorrelated random numbers that have a suitable distribution and then pass that sequence through a filter.  Unfortunately, filtering affects the signal level, and the complexity of the filter makes computations inefficient.  Alternatively, the VHDL algorithm in Listing 1 requires very little computation, __ Circuit Design by Ove Johansson, CelsiusTech Systems, Stockholm, Sweden

AN-637: Realizing Trigonometric Functions with the Multifunction Converter LH0094 -  National Semiconductor Application Note

Calculator program finds closest standard-resistor values -  31-Mar-05 EDN-Design Ideas - Find the poles and zeroes of elliptic-filter designs using Darlington’s algorithm implemented on a calculator __ Circuit Design by Fernando Salazar-Martínez, Alan Altamirano-Cruz, and David Báez-López, Department of Engineering Electronics, University of the Americas, Puebla, Mexico

Circuit Provides More Accurate Multiplication -  12/15/11 EDN-Design Ideas - Convert into and out of the sampled-data domain to get an accurate multiplication.  Common analog multiplying devices employ methods using transistor parameters.  Precise versions of these devices use the logarithm method of multiplication.   __ Circuit Design by Yakov Velikson, Lexington, MA

Circuits Provide Nonlinearity -  EDN-Design Ideas 02/28/2000    In analog design, you might need to create an amplifier with nonlinear dynamic characteristics—for example, logarithmic, exponential, or square-law.  Usually, such amplifiers are complicated.  However, the project often does not require mathematical precision.  For example, you might just need to increase the dynamic range of an amplifier, or to eliminate saturation for an extended input-voltage range. __ Circuit Design by Abel Raynus

Circular slide rule provides quick results -  EDN-Design Ideas - March 26, 1998    [ NOTE : File has multiple design, scroll for this one.]  In analog-circuit design, most calculations you make need not be very precise. If you need an LED-current calculation or a coupling-capacitor value, for example, ±5% or even ±10% accuracy is usually adequate. It's sometimes inconvenient to make these calculations with a pocket calculator. For example, finding the cutoff frequency of a 3.3-kiloohms/47-pF network requires approximately 20 key presses. __ Circuit Design by Jacek Pawlowski, PW INMEL, Zielona Góra, Poland

Commutating Amp Performs Log Function -  02/16/95 EDN-Design Ideas - Customarily, logarithmic amplifiers exploit the V/I characteristic of a pn junction or approximate a log function in a piecewise-linear fashion.  Both approaches suffer from inherent limitations.  A pn junction's V/I characteristic has large temperature coefficients requiring ad hoc compensation circuitry.  Piecewise-linear approximations exhibit discontinuities in their first derivatives __ Circuit Design by Moshe Gerstenhaber and Stefano D'Aquino, Analog Devices, Wilmington, MA

Cubic Interpolation Hikes Table's Accuracy -  02/16/95 EDN-Design Ideas - You can obtain very accurate approximations of a function from only a few data points contained in a look-up table, trading storage space for calculation time.  For example, you can derive .    __ Circuit Design by Brad Eckert, Industrial Commercial Electronics, Buffalo, NY

DSP Algorithm Measures Frequency & Damping  -  10/08/98 EDN-Design Ideas - The time-domain DSP algorithm described here allows you to measure the key parameters—natural frequency and damping—in linear, second-order electromechanical systems.  The method applies to a range of electromechanical transducers (electromagnetic or electrostatic], including dynamic speakers, seismic geophones, micromachined sensors, and other systemsContains several designs, scroll to find this one.   __ Circuit Design by Olga Belousova, Los Alamos, NM, and Alexander Belousov, New York, NY

Efficient Algorithm Generates Random Signal -  12/05/96 EDN-Design Ideas - A common way to simulate a sequence of bandwidth-limited-noise samples is to start with a sequence of uncorrelated random numbers that have a suitable distribution and then pass that sequence through a filter.  Unfortunately, filtering affects the signal level, and the complexity of the filter makes computations inefficient.  Alternatively, the VHDL algorithm in Listing 1 requires very little computation, __ Circuit Design by Ove Johansson, CelsiusTech Systems, Stockholm, Sweden

Fast algorithm computes histograms -  10/28/99  EDN-Design Ideas - A histogram is a convenient method of presenting statistical features of data; you can use a histogram for an estimate of the probability density function of a random phenomenon.  To prepare a histogram entails dividing the interval occupied by data values __ Circuit Design by Lukasz Sliwczynski

Genetic algorithms: programs that boggle the mind -  EDN  Design Ideas - 03/03/1997    Assume that you construct a simple device consisting of a power source and two potentiometers in series with an incandescent-light bulb  (Figure 1) .  Assume also that you can rotate the potentiometers 180°, from -90° to +90°, and that the point of least resistance for each potentiometer is in its center  (upright) position.  Suppose you set the potentiometers to random positions, then you proffer the device to friends and ask them to play with it--using the potentiometers, not the supply voltage--to make the light as bright as possible.  Most people select one potentiometer, turn it a little to the left or right, and note the result. __ Circuit Design by Clive "Max" Maxfield, Intergraph Computer Systems

Hardware Random Number Generator -  This page describes my effort to construct a random number generator with as high a security-to-cost ratio as I can manage.  I warn anyone who intends to use any of this for anything serious to engage in a rigorous study of the weaknesses inherent in this design.  The PN junction of Q1 is reverse biased to produce avalanche noise __ Designed by Aaron Logue

Linear potentiometer provides nonlinear light intensity control -  04/28/05  EDN-Design Ideas - Circuit matches light control to eye’s intensity-response curve __ Circuit Design by Stephan Goldstein, Analog Devices, Wilmington, MA

Log Amp uses capacitor-charging law -  01/10/02 EDN-Design Ideas - The novel logarithmic amplifier in Figure 1 relies on the exponential charging characteristics of a simple RC circuit.  The expression for the time, T, required for a capacitor, C, to reach a voltage  (VIN–VK) from 0V, when charged through a resistor, R, with an applied voltage of VIN, is VIN–VK=VIN  (1–e–T/RC) , where VK is a fixed voltage.  The expression for T reduces to T=RCln (VIN/VK) , clearly showing an inherent logarithmic characteristic.    __ Circuit Design by Jayashree Raghuraman and Ajoy Raman, Aeronautical Development Establishment, Bangalore, India

Log-ratio Amplifier has six-decade dynamic range -  27-Nov-03 EDN-Design Ideas - You need optical-power monitoring to guarantee overall system performance in fiber-optic communication systems.  Logarithmic-signal processing can maintain precise measurements over a wide dynamic range.  The wide-dynamic-range signal undergoes compression, and the use of a lower resolution measurement system then saves cost __ Circuit Design by Reza Moghimi, Analog Devices, San Jose, CA

Mathcad Functions Perform Log Interpolation -  30-Oct-03 EDN-Design Ideas - MathCAD provIdeas a number of interpolation and curve-fitting functions, so that, given a set of X-Y data points, you can estimate the Y value for any given X coordinate.  Unfortunately, these functions work poorly with data that is to be displayed in a nonlinear (logarithmic] manner.  Examples of these functions are  Using the built-in "linterp" function, MathCAD estimates and plots the data (Fig __ Circuit Design by James Bach, Delphi Delco Electronics Systems, Kokomo, IN

Mixed Signal Algorithm Tests Transducers -  04/24/97 EDN-Design Ideas - A simple test procedure  (Reference 1) allows you to measure damping coefficient beta in electromechanical transducers, such as speakers, microphones, and seismic geophones.  The method is based on stimulating the transducer with a dc step current, IS, and then separately integrating the positive and negative half-waves of the transducer's terminal voltage, V (t) , after removing the step current.  The integrals of the positive and negative waveforms contain all the necessary information to calculate beta.   __ Circuit Design by Alex Belousov, Rego Park, NY

Model fixed-point DSP arithmetic in C -  03/18/99 EDN-Design Ideas - NOTE :  Page includes several designs.  Scroll to find this one.  You can run initial high-level simulations of custom numerical algorithms, such as digital filters, using floating-point numbers in an environment such as C or Matlab.  Unfortunately, you won't see include fixed-point effects, such as truncation due to limited precision and register overflow, until you use a Hardware Design Language  (HDL) , such as Verilog or VHDL.  However, a technique that models these effects in C—the function "bit_limit" in Listing 1—provIdeas faster execution and better portability than HDLs and allows early exploration of the trade-off between bus width and performance.   __ Circuit Design by Roger Maher, SSL Ltd, Dublin, Ireland

Motor-Drive Algorithm Saves Space & Cycle -  02/17/94 EDN-Design Ideas - The algorithm embodied in the second subroutine in Listing 1  generates the excitation sequence for most permanent-magnet and hybrid stepper motors.  This subroutine is smaller than subroutines that spring from other algorithms __ Circuit Design by Jose A P Machado da Silva, University of Porto, Porto, Portugal

Nodal Analysis -   (spice design)  __ Designed by Rick 

Non-Linear DC Analysis -   (spice design)  __ Designed by Rick 

Primer on binary arithmetic rounding -  01/21/99 EDN-Design Ideas - NOTE : Page includes several designs.  Scroll to find this one.   As digital communications and data compression/decompression proliferate, signal-processing functions grow in importance.  Whether you’re dealing with hard-wired logic or programmable engines, an understanding of binary-arithmetic rounding is important in getting correct and consistent results.  Before we discuss rounding, consider a binary number (Figure 1) Page includes several designs.  Scroll to find this one __ Circuit Design by Tom Balph, Motorola SPS, Tempe, AZ

Provides More Accurate Multiplication -  12/15/11 EDN-Design Ideas - Convert into and out of the sampled-data domain to get an accurate multiplication.  Common analog multiplying devices employ methods using transistor parameters.  Precise versions of these devices use the logarithm method of multiplication.  This method involves the addition of logarithms and an exponential conversion  (Reference 1) .  Using these methods, you can achieve a minimal error of ±0.1%.  This Design Idea reduces the error, employs readily available standard components, and maintains the correct voltage scale.   __ Circuit Design by Yakov Velikson, Lexington, MA

Reference stabilizes exponential current -  10/25/01 EDN-Design Ideas - In an antilog converter, the difference between the base voltages of two transistors sets the ratio of their collector currents  The use of matched transistors balances the first-order temperature coefficient but leaves a temperature-dependent gain term, q/kT.  Classic antilog circuits use a thermistor in the drive circuitry to correct this temperature dependency __ Circuit Design by Tom Napier, North Wales, PA

Resistance Calculator Yields Precise Values -  08/03/95 EDN-Design Ideas - For times when the nearest preferred resistor value isn't close enough to the desired value, a program comes in handy.   (You'll find the executable ZIPfile and several source-code files for the program in EDN BBS /DI_SIG #1740.) The program finds all combinations of two series or parallel connected resistors, within a specified tolerance of the required value, using only preferred values from the E6, E12, E24, and E96 ranges  (6, 12, 24, and 96 different values per decade) .    __ Circuit Design by David Kirkby, Department of Medical Physics, University College London, London, UK/

Simple Circuits Provide Nonlinearity -  EDN-Design Ideas 02/28/2000    In analog design, you might need to create an amplifier with nonlinear dynamic characteristics—for example, logarithmic, exponential, or square-law.  Usually, such amplifiers are complicated.  However, the project often does not require mathematical precision.  For example, you might just need to increase the dynamic range of an amplifier, or to eliminate saturation for an extended input-voltage range. __ Circuit Design by Abel Raynus

Single Ended Adder/Subtractor -  This circuit shows Using Vcom as third algebraic input in an addition/subtraction circuit.  This is useful for adding or translating signals.  __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Single-cycle logarithms & antilogs -  11/11/13  EDN-Design Ideas - Here are some very fast log  (and antilog) blocks well-suited to FPGA implementation __ Circuit Design by Michael Dunn

Take a look inside the SPICE engine.   How it works. -   (spice design)  __ Designed by Rick 

Transient Analysis -  One of the most complex and intriguing capabilities of the SPICE algorithm is the Transient Analysis.  How do we take a collection of resistive and energy-storage components, then find its time response to an arbitrary input waveform? Yes, you could formulate and solve the differential equations to get the response versus time, but SPICE is not a differential equation solver  (spice design) 

Use Derivatives to catch RF calibration errors -  05/27/99 EDN-Design Ideas - Many RF-system calibrations involve checking for minimum power available or removing system offsets.  One example is the checking of an RF source’s output powerPDF has several circuits, please scroll to find this one.    __ Circuit Design by Steven C Hageman, Hewlett-Packard Co, Santa Rosa, CA

Versatile power-supply load uses light bulbs -  02/07/02 EDN-Design Ideas - Improvising loads for bench-testing and designing power supplies is often a frustrating and sometimes hazardous experience.  When you push large power resistors to their limit, they tend to burn benches and melt solder connections.  Many electronic loads are on the market but are usually expensive and of laboratory-type precision and often represent overkill for the average designer __ Circuit Design by William Sloot, Computron Display Systems, Mount Prospect, IL

White LED driver provides 64 step logarithmic dimming -  10-Jun-04 EDN-Design Ideas - The circuit of Figure 1 is designed for portable-power applications that require white LEDs with adjustable, logarithmic dimming levels.  The circuit drives as many as four white LEDs from a 3.3V source and adjusts the total LED current from 1 to 106 mA in 64 steps of 1 dB each.  The driver is a charge pump that mirrors the current ISET (sourced from IC3's SET terminal] to produce a current o __ Circuit Design by William Hadden, Maxim Integrated Products, Sunnyvale, CA


Math Function: Logarithmic

 


Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches



 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |   
Privacy Policy


Discovercircuits.com endeavors to credit original designers.   Please alert us by eMail so we can
delete links to material that have been copied without your permission
.   Thank you.


© Copyright of all original material on this website is the property
of David A. Johnson, P.E. (Dave Johnson & Associates ) unless otherwise noted.  

Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.
All material is provided "as is" without guarantees or warranty of any kind, either expressed or implied.