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Last Updated: November 22, 2021 02:42 PM

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407

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

1kh Synthetic Inductor - Inductors can be mimicked quite easily using operational amplifiers.  The circuit shown here was developed to have an inductance of 1000 H (say, one thousand Henry) with good damping.  Using this design you can build a resonant circuit with a center frequency of less than 1 Hz.  The slow behavior allows you to use conventional __ 

A Handy Pen Torch - This easy to construct “Handy pen torch” electronic circuit and low component count, uses two power white LEDs for lighting.  Low volt (4.8V dc) supply available from the built in rechargeable Ni-Cd battery pack is first converted into two channel (independent) constant current sources by two pieces of the renowned precision adjustable shunt regulator chip __ 

Basic Homebuilt Discrete DTL gates (Diode Transistor Logic) - We can surely take care of that! The only really serviceable transistor gates that are stand-alone and hobbyist-ready are the inverter-based gates, tis true, but we need to add a few things before we have something like a gate that you can count on and not have to fiddle around with it and the problem of successive array levels from logical input (left) to output (right) on a page or standard diagram. __ Designed by Richard Steven Walz

Biass Serve HF andVHF Bands - 09/14/00 EDN-Design Ideas - Bias circuits are passive networks that you use to apply dc excitation to various active circuits.  The monitor tee, which is also known as the bias tee, has been commercially available for more than 40 years at microwave frequencies.  The original products provide useful frequency ranges of two to one through five to one.  More recent cost-effective bias tees cover 0.1MHz to more than 4 GHz.  Other designs are available that extend well into higher microwave-frequency bands (Reference 1).  Another bias circuit is the bias-passing attenuator, which is also commercially available at microwave frequencies Design  by Richard Kurzrok

Borax Rectifier - Experiments with a borax or baking soda rectifier.   __ Designed by Nyle Steiner K7NS

Cancel Amplifier Error - 12/09/99 EDN-Design Ideas - The circuit in Figure 1 , using a low-offset amplifier, is a basic ohmmeter circuit common in multimeters, except for the addition of the two.   PDF has many sicrcuits, scroll for this one.    Design  by David Magliocco, CDPI, Scientrier, France

Cancel Sensor-Wiring Error with Bias-Current Modulation - 11-Jun-09 EDN-Design IdeasThis circuit cancels the wiring-resistance error inherent in diode temperature sensors and requires only two conductors in the sensor cable Design  by W Stephen Woodward, Chapel Hill, NC

Carry-Save Addition Saves Logic & Time - 11/09/95 EDN-Design Ideas - Summing multiple operands is a common operation in signal-processing applications.  One such application requires summing eight 16-bit operands to generate a 19-bit result.  To achieve  required setup time (tS]and clock-to-output time (tCO]in  system, you need pipelining.  Figure 1 shows  straightforward way to implement this multiple-operand Design  by Chris Jones, Cypress Semiconductor San Jose, CA

Circuit Computes First Derivative - 12/31/69 EDN-Design Ideas - The circuit in Figure 1 computes the derivative of an input signal as the integral of the input signal minus the signal itself.    Design  by Richard Panosh, Vista, Bolingbrook, IL

Circuit forms shaping Amp & Amplitude Detector - 03/15/01 EDN-Design Ideas - The use of solid-state detectors connected to charge amplifiers requires appropriate conditioning of the output signals, because of the signals' long decay time.  Moreover, you must 'stretch' the peaks of the shaped pulses for a period sufficient for A/D conversion.  For a single detector, you can use a relatively expensive module.  For a large detector array, you need to develop an ASIC.  For a moderate number of detectors, you can use an inexpensive circuit that handles an array of 19 drift diodes connected to a scintillating crystal of cesium-iodide (Figure 1). Design  by Elio Rossi

Compute First Derivative - 12/31/69  EDN-Design Ideas - The circuit in Figure 1 computes the derivative of an input signal as the integral of the input signal minus the signal itself.   Design  by Richard Panosh, Vista, Bolingbrook, IL

Convert negative inputs to positive outputs - 04/23/09  EDN-Design Ideas - Create a 3.3 V source from a –5V supply Design  by Shane Chang and Budge Ing, Maxim Integrated Products, Sunnyvale, CA

Convert signals to proper logic levels - 02/05/09  EDN-Design Ideas - Reduce digital-voltage levels to those compatible with microcontrollers Design  by Abel Raynus, Armatron International Inc, Malden, MA

Converting A DCM Motor - We recently bought a train set made by a renowned company and just couldn’t resist looking inside the locomotive.  Although it did have an electronic decoder, the DCM motor was already available 35 (!) years ago.  It is most likely that this motor is used due to financial constraints, because Märklin (as you probably guessed) __ 

Current Amp Provides Frequency Modulation - 12/04/97 EDN-Design Ideas - You can use current-feedback op amps in many VHF-band RF applications.  Thanks to their 150-MHz bandwidth, current-feedback op amps can simplify your design task by replacing discrete components, such as bipolar transistors and FETs, in high-frequency circuits.  The circuit in Figure 1 is a frequency modulator that generates a 55-MHz VHF signal.   Design  by M Pereira and A del Rio, University of Vigo, Spain -- December 4, 1997

De-embed transmission lines with FIR filters - EDN-Design Ideas - 04/02/2015    This DI uses MATLAB to design de-embedding filters which clean up high-speed signal measurements Design  by Mohit Kumar

Designing for reliability: a checklist - 11/21/96 EDN-Design Ideas.  Building products that stand the test of time requires understanding reliability engineering and mathematics.  You must also understand reliability prediction and a failure's effect on the user.  Reliability engineering studies product failure, its causes, and its prevention.  It concerns itself with eliminating the costs of failure for assembly rework, service and repair, and customer ownership.  The reliability engineer's primary goal is to aid the designer in developing a product that is buildable, serviceable, and reliable.   Design  by Ki Punches

DPGA conditions signals with negative time constant - 19-Mar-09 EDN-Design Ideas - With two op amps and three analog switches, you can build a programmable amplifier that conditions signals before digitizing Design  by W Stephen Woodward, Chapel Hill, NC

Exclusively select 1 of N relays - EDN-Design Ideas - 03/31/2014     Simple elegance reigns in this 1-of-N selector Design 

Fast & Accurate 80MHz Amplifier Draws Only 2mA - DN286 Design Notes__ Linear Technology/Analog Devices

Flashing Neons (NE-51 / NE-2) - In this circuit, one, two or three neon indicator bulbs can be made to flash in sequence at rates determined by the R and C values.  In the single stage circuit, using one lamp, the capacitor charges through the resistor until the ionization potential of the neon is reached (about 70 volts) and __ Designed by Bill Bowden

Fractions Eliminate Floating-Point Multiple - 11/23/95 EDN-Design Ideas - Inexpensive µCs offer better than average performance for many applications.  The devices do not include hardware to do floating-point math, however.  You often need to multiply or divide an integer by a floating-point constant, such as pi, square root of 2, or such circuit-specific values as the gain of an amplifier.  You are interested only in the integer portion of the result.  Using a floating-point representation for the constant would entail linking in -- or, worse -- writing, large, slow library functions.  Fortunately, you can achieve excellent accuracy by using the ratio of two integers to approximate the constant.    Design  by Michael Gauland, Tektronix Inc  Beaverton, OR

Free FilterCAD 3.0 Software Designs Filters Quickly & Easily - DN245 Design Notes__ Linear Technology/Analog Devices

Game Show Who's First Indicator Lights - The circuit above turns on a light corresponding to the first of several buttons pressed in a "Who's First" game.  Three stages are shown but the circuit can be extended to include any number of buttons and lamps.  Three SCRs (silicon controlled rectifiers) are connected with a common cathode resistor (50 ohm) so that when any SCR conducts, the voltage on the cathodes will rise about 7 volts above the voltage at the junction of the 51K and 1K ohm resistors and prevent triggering of a second SCR.  When all lamps are off, and a button is pressed, the corresponding SCR is triggered due __ Designed by Bill Bowden

Generating Long Time Delays - Generating long delays of several hours can be accomplished by using a low frequency oscillator and a binary counter as shown below.  A single Schmitt Trigger inverter stage (1/6 of 74HC14) is used as a squarewave oscillator to produce a low frequency of about 0.5 Hertz.  The 10K resistor in series with the input (pin 1) reduces the capacitor discharge current through __ Designed by Bill Bowden

Generating Negative 5 Volts from 9 Volt Battery - A 555 timer can be used to generate a squarewave to produce a negative voltage relative to the negative battery terminal.  When the timer output at pin 3 goes positive, the series 22 uF capacitor charges through the diode (D1) to about 8 volts.  When the output switches to ground, the 22 uF cap discharges through the second diode (D2) and charges the 100 uF __ Designed by Bill Bowden

Glass Blower - NOTE : Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Good things come in small IC packages - 02/03/97 EDN-Design Feature  Analog functionsin tiny IC packagesgive you pc-board-layout flexibility, but consider design guidelines,thermal management,and manufacturing issuesas you "go small.   "    In the rank and file of digital and analog ICs, analog devices have always marched to a different drummer.  The latest in IC packaging confirms this fact.  Although digital ICs are moving into ever-larger packages with hundreds of leads, analog ICs are increasingly available as minimal-function components in ever-tinier packages the size of pinheads or match heads.    Design  by Design Feature by Bill Schweber, Technical Editor

GSM Phone Jammer-P2JBZ - Schematic only __ Designed by va3iul

Hand Soldering of MNA Amplifiers - AN-60031 Application Note__ MiniCircuits.com

Hex Level Shift Shrinks Board Space - DN20 Design Notes__ Linear Technology/Analog Devices

High Current MOSFET Flip Flop with Debounced Pushbutton - This circuit was adapted from the "Toggle Switch Debounced Pushbutton" by John Lundgren.  It is useful where the load needs to be switched on from one location and switched off from another.  Any number of momentary (N/O) switches or push buttons can be connected in parallel.  The combination (10K, 10uF and diode) on the left side of the schematic insures the circuit powers up with the load turned off and the NPN transistor conducting.  These components can be omitted if the initial power-on condition is not an issue. __ Designed by Bill Bowden

High Efficiency 30A Low Profile PolyPhase Converter - DN211 Design Notes__ Linear Technology/Analog Devices

High Efficiency 500kHz 4.5Step-Down Converter in an SO-8 Package - DN181 Design Notes__ Linear Technology/Analog Devices

High Efficiency High Density PolyPhase Converters for High Current Applications - AN77 Linear Technology This App Note addresses the following questions.  How much do I gain by using a PolyPhaseTM architecture? How many phases do I need for my application? How do I design a PolyPhase converter? The design example of an LTC1629-based, 6-phase 90A power converter is presented.  The mathematical equations and graphical curves for__ Linear Technology/Analog Devices

High Efficiency High Density Power Supply Delivers 200A Without Heat Sinks - DN1001 Design Notes__ Linear Technology/Analog Devices

High Efficiency PolyPhase Converter uses Two Inputs for Single Output - DN222 Design Notes__ Linear Technology/Analog Devices

High Frequency Active Antialiasing Filters - DN313 Design Notes__ Linear Technology/Analog Devices

High Frequency Amplifier Evaluation Board - DN50 Design Notes__ Linear Technology/Analog Devices

High Speed Amplifier Techniques - AN47 Linear Technology This application note, subtitled "A Designer's Companion for Wideband Circuitry, " is intended as a reference source for designing with fast amplifiers.  Approximately 150 pages and 300 figures cover frequently encountered problems and their possible causes.  Circuits include a wide range of amplifiers, filters, oscillators, data converters and signal conditioners.  Eleven appended sections discuss related topics including oscilloscopes, probe selection, measurement and equipment considerations, and breadboarding techniques.  __ Linear Technology/Analog Devices

Higher-Level Languages, or More Hardware for SLD? - EDN-Design Ideas - April 30, 2001    Design verification has quickly evolved into one of the most critical steps in the system-design process.  Recent studies now indicate that as much as 70 percent of the design cycle is now spent on verification.  Two stories have grabbed most of the attention this year: system-level design (SLD) and hardware-based verification.   Design  by Jason Andrews

HP 8904A Repairs - I got a supposed-to-be-working HP 8904A Synthesized AF generator which passed self tests and had no obvious problems, so I took the time neccesary to carefully clean it before doing further tests.  After hooking it to the scope, surprise __ Designed by Roberto Barrios EB4EQA

HP Sticky Buttons - Some of the 80's HP/Agilent Test equipment uses this pushbutton switches (HP P/N 5060-9436) , which may get quite hard to push, with a nasty feeling of being stuck and then released with a loud sound, like those clickers used to train dogs.   __ Designed by Roberto Barrios EB4EQA

Humnuller - This project is a portable (i.  e.  PC-less) hum rejecter (or more accurately, hum estimator) principally for VLF listening application.  It employs the PIC’s ADC to sample the hum waveform, and performs a special type of filtering to isolate it.  The hum waveform is then reproduced on an external DAC so that it can be subtracted from the VLF signal.  The problem with hum is that it is rarely a single frequency.  Switching power supplies, light dimmers and many other appliances conspire to distort the mains waveform so that, by the time it reaches your circuit, it contains many harmonics besides the fundamental line frequency.  This makes a simple analogue notch filter ineffective for hum rejection.   __ Contact Karen's Microprocessor Projects

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