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Amplifier Circuits:  Logarithmic Page 1
Amplifier -- Main Page          Math Functions -- Main Page
Logarithmic Amplifiers:  #-B        C-L       M-R        S-Z

Last Updated on: Thursday, April 07, 2016 01:01 PM

Circuits Designed by Dave Johnson, P.E. :
  • AC Peak Detector that is Precise  -  This unique circuit uses a very inexpensive voltage comparator to form a peak detector. The DC voltage produced tracks the positive peak of the input signal.  It works from about ten millivolts to about 10 volts peak to peak.  The maximum frequency is about . . . [Hobby Circuit designed by David Johnson P.E.,  02/11/02]

  • Acceptable Voltage Indictor  -  I have used this circuit many times in custom test fixtures where a simple go-no go indication was needed.  The circuit can also be used to adjust a particular voltage be within specific high or low limits.  The three LEDs will indicate if the voltage is . . . [Circuit by David Johnson P.E.,  02/09/02]

  • Battery Charge Current Indicator  -  This circuit turns on a LED whenever it detects at least 25ma of battery charge current . . . [Circuit by David Johnson P.E.,  07/23/06]

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

A Compact Algorithm using the ADXL202 Duty Cycle Output -  AN-603 Analog Devices App Note -   …

 

A primer on binary-arithmetic rounding -  01/21/99 EDN Design Idea (contains 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).… [by Tom Balph, Motorola SPS, Tempe, AZ]

 

AC Peak Detector that is Precise -  This unique circuit uses a very inexpensive voltage comparator to form a peak detector. The DC voltage produced tracks the positive peak of the input signal.  It works from about ten millivolts to about 10 volts peak to peak.  The maximum frequency is about . . . [Hobby Circuit designed by David Johnson P.E.,  02/11/02]

Acceptable Voltage Indictor -  I have used this circuit many times in custom test fixtures where a simple go-no go indication was needed.  The circuit can also be used to adjust a particular voltage be within specific high or low limits.  The three LEDs will indicate if the voltage is . . . [Circuit by David Johnson P.E.,  02/09/02]

 

Algorithm Converts Random Variables to Normal -  05/11/95 EDN Design Idea   Although normally distributed random variables are essential for many engineering analyses, software packages usually provide only a function that generates uniformly distributed random samples over the range [0,1].… [by Edward Beadle, Brookhaven National Laboratory, Upton, NY]

 

Algorithm extracts roots of decimal numbers -  04/29/99  EDN Design Idea (contains several designs, scroll to find this one)   "Algorithm extracts cube root" (EDN, Jan 15, 1998, pg 100) covers only the one-third power (cube root). In contrast, the C routine in Listing 1 calculates the Kth root (X1/K) of positive decimal numbers X. Both K and X can vary widely. You type in X, K, and an estimate of the root; the routine then calls the calcRoot function in the software program. Upon calculating the root, the routine prints on screen the number of iterations performed and the root result X1/K. … [by Frank Vitaljic, Bellingham, WA]

 

Algorithm Generates Random Signal -  12/05/96 EDN Design Idea   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, filt… [by Ove Johansson, CelsiusTech Systems, Stockholm, Sweden]

 

Algorithm Keeps Data Safe -  01/21/10  EDN Design Idea   Prevent data loss against power blackouts and other interruptions… [by Luis G Uribe C, Caracas, Venezuela]

 

Algorithm Nulls DC Offsets In DS -  09/15/94 EDN Design Idea   One problem associated with converting analog signals to digital samples is ensuring that the zero level of an analog signal (minus its dc offset, if any) converts to a digital sample of exactly zero. If the analog signal's zero … [by V Solovyov, Rossiya, Russia]

 

Algorithm Transforms Filter Coefficients -  01/21/99 EDN Design Idea   (File includes several circuit ideas, please scroll to find this one.)To synthesize infinite-impulse-response (IIR) -filter functions, expressed as H (z) , you commonly use analog prototype-filter functions, expressed as H (s) , using the bilinear-z transform. This operation entails some algebraic complexity in calculating the filter coefficients. The simple algorithm shown here transforms the prototype-filter coefficients (W0, W1, W2) to the IIR digital-filter coefficients (U0, U1, U2).… [by Frank Vitaljic, Bellingham, WA]

 

Algorithm Yields Precise Bessel Function -  11/09/95 EDN Design Idea   You frequently need to determine the Bessel function of the first kind, Jn (x) , for the analysis of modulated and complex waveforms. Such analyses could include, for example, routine verification of transmitter phase- or frequency… [by Brian Geelen, Satellite Microwave & Communications LtdWeert, The Netherlands]

 

Amplifier for a Xenon Lamp Flash Detector  -  This circuit uses a small 2.5mm square photo diode in conjunction with a 100mH coil to detect the short light flashes from a xenon lamp.  The coil makes the circuit immune to normal room lights.  Its 10mv sensitivity can detect light flashes from a range . . . [Circuit by David Johnson P.E.,  02/15/02]

 

AN-311: Theory & Applications of Logarithmic Amplifiers -  National Semiconductor Application Note  …

 

AN-405: Increasing the Speed of the Output Response of the AD606 -  AN-405 Analog Devices App Note…

 

AN544: Math Utility Routines -  Microchip Application Note Published 26-Aug-97  …

 

AN-603: A Compact Algorithm using the ADXL202 Duty Cycle Output -  AN-603 Analog Devices App Note -   …

 

AN-604: Using the ADXL202 Duty Cycle Output -  AN-604 Analog Devices App Note - …

 

AN752: AN752 CRC Algorithm for Mcrf45x Read/Write Device -  Microchip Application Note Published 15-Mar-01  …

 

AN788: Numerical Integration Techniques TC7109 -  Microchip Application Note Published 12-Nov-02  …

 

Basic logarithmic Amplifier using op-amp and NPN transistor -  …

 

Battery Charge Current Indicator -  This circuit turns on a LED whenever it detects at least 25ma of battery charge current . . . [Circuit by David Johnson P.E.,  07/23/06]

 

Bodmas Rule -  The term 'BODMAS' is an acronym for 'bracket,' 'of', 'division,' 'multiplication,' 'addition' and 'subtraction' and the 'BODMAS rule' is a mnemonic for the hierarchy of various arithmetical operators. A mathematical expression may involve a number of operators, but only one of them must be carried out first. The order of priority, as we are familiar from school days, follows: 'Bracket' followed by 'of,' 'division,' 'multiplication,' 'addition' and then 'subtraction' in that order. … [© EFY Enterprises Pvt. Ltd. All rights reserved.]


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Logarithmic Amplifiers:  #-B        C-L       M-R        S-Z


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