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Tester or Measurement (Instrument) Circuits

Test Equipment:  #'s - A        B - D        E - G
H - L        M - O        P - S        T - Z


Last Updated: October 24, 2017 02:55 PM
Circuits Designed by Dave Johnson, P.E. :

DC Brushless Motor Monitor -  The circuit below was requested by a person needing a way to keep track of the number of hours a 24v DC brushless motor was in operation.  The circuit taps into a bit of the power going into the motor using a bridge rectifier and filter capacitor.  The voltage produced feeds the input of a small solid state relay.  The output of the relay routes AC power to an hour meter, every time the brushless motor is turned on.  This same circuit could be used with other DC motors with some simple modifications . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2005

DC Current Bidirectional Indicator -  This circuit is handy for battery powered systems.  The circuit is self-powered using a single 3v lithium coin cell.  The current draw is so low that the battery should last for years.  The hobby circuit flashes a red LED when DC current is drawn from the battery and flashes a green LED whenever current flows into the battery.  Two “probe” input wires connect across a section of cable, which acts as a shunt resistor.  A voltage of only 5mv in either direction will trigger a LED indication . . . Hobby Circuit designed by David Johnson P.E.-March, 2011

Delayed Pulse Generator -  This circuit generates a short 10ms pulse 15 minutes after a “start” pushbutton switch is activated. . . Circuit by David A. Johnson P.E.-October, 2005

Detect Clear Fluid -  This circuit detects when a clear fluid is inside a piece of clear plastic tubing.  it can be used for fluid level control and monitoring . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2012

Detect Motion with a Piezo Device -  Using a piezoelectric device, this circuit will activate a beeper whenever the circuit is moved.    it could be used as an earthquake alarm. . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747


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

Current-sense Amplifier precisely measures Low side -  09/16/99  EDN Design Ideas:  Several integrated high-side current-sense amplifiers, such as the MAX4172 (Maxim integrated Products, www.maxim-ic.com) , make it easy to measure the current from a positive power supply.  With a couple of resistors, these devices provide a ground-referenced voltage output that is proportional to the delivered current (Figure 1a).   __ Circuit Design by John Ursoleo

Current-sense IC Prevents OverCurrent Damage -  04/25/96 EDN Design Ideas:  CMOS -interface ICs  serve as gateways to the wired connections in electronic systems.  Mishandling those external connections can damage the interface ICs  by causing shorts to ground or by applying voltages that result in latch-up.   __ Circuit Design by Gary Sellani, Maxim Integrated Products, Sunnyvale, CA

Current-Sense Monitor & MOSFET Boost Output Current -  28-May-09 EDN Design Ideas:  You can bypass BDC current-settings resistors and use a MOSFET to increase current __ Circuit Design by Gyula Diószegi and János Nagy, Divelex Ltd, Budapest, Hungary

Current-sensing scheme improves PFC on/off sequences -  06/27/02 EDN Design Ideas:  PFC (power-factor-correction] preconverters typically use the step-up, or boost, configuration, because this type of converter is relatively easy to implement (Figure 1).  However, this topology requires the output voltage to be higher than the input voltage.  When this condition is not the case—for example, with on/off sequences or under load conditions—some inrush current flows thro __ Circuit Design by Joël Turchi, On Semiconductor, Toulouse, France

Customised Solution for Measurements: Building a Personal Multimeter (Part-2) -  Continued from Customised Solution for Measurements: Building a Personal Multimeter (Part-1) Once we are done measuring the voltage and current, let's take a look at the other measurable parameters that can be...__ Electronics Projects for You

Customized potentiometers aid Amplifier Design -  11/11/99  EDN Design Ideas:  The circuit in Figure 1 is a model of an amplifier circuit whose cutoff frequency and gain are functions of the values of variable resistors.  A first-order, RC lowpass filter establishes the cutoff frequency, and a traditional noninverting op-amp circuit __ Circuit Design by Chuck Wojslaw

Cut Phone Line Detector -  A while ago I got an email asking for the schematic of a circuit to detect cut phone lines.  it didn't take me long to find this circuit in Electronics Now.  When the circuit detects that a phone line has been cut, it activates a MOSFET which can be used to drive a relay, motor, etc.  it can also be connected to a security system __ Designed by Aaron Cake

Cut Phone Line Detector -  This circuit speaks for itself.    When the phone line is okay, Q1 acts as a short with a very high ohms value via R1, R2, and R3 for a total of about 66 MegOhm so very high.  When the phone line is cut (Tony van Roon's open) , it activates the MOSFET (Tony van Roon's Q3) via transistor Q2 to drive the load.    Substitutes are fine, none of the components are critical __ Designed by Tony van Roon  VA3AVR

CW & CCW Alternating Motor Driver -  A while back a company needed a motor controller for a custom door latching system.    The system used a small brush motor with a speed reduction gear to both latch and unlatch the door.    When pulsed for about 250ms in the clockwise direction, the motor would unlatch the door . . . Hobby Circuit designed by Dave Johnson P.E.-September, 2010

Daggerboard Position Detector -    NOTE: Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Darling SE Tube Amplifier -  Scroll down to find this circuits.  in the diagram I'veput the transistor numbers as the ones I'veused, although you can use standard 2n3904's etc in these positions without problems as they're similar spec.  The transformer used is a normal audio output transformer, such as an LT700 __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Dashboard Digital Voltmeter Project -  This project is heLPFul to anyone who drives an automobile.  I had found this project at the local libary.  in an old publication.  I made it and it worked fine.  Below are the complete text and schematic of the Dashboard Digital Voltmeter.  I re-typed the text and re-drew the schematic.  as the printing from the book was old and faded.  Sit back and read the story why this LED display might just save you from being stranded on the road!  __ Designed by braincambre500 @ yahoo.com

Data-acquisition system captures 16-bit voltage measurements using the USB -  05/25/06  EDN Design Ideas:  The USB has become the interface of choice for connecting to PCs.  Available on all relatively modernPCs, the USB offers a standard connector and can supply power to peripheralsat 5V and as much as 100 mA of current.  The circui __ Circuit Design by Terry Millward, Maxim Integrated Products Inc, Blonay, Switzerland

DC Brushless Motor Monitor -  The circuit below was requested by a person needing a way to keep track of the number of hours a 24v DC brushless motor was in operation.  The circuit taps into a bit of the power going into the motor using a bridge rectifier and filter capacitor.  The voltage produced feeds the input of a small solid state relay.  The output of the relay routes AC power to an hour meter, every time the brushless motor is turned on.  This same circuit could be used with other DC motors with some simple modifications . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2005

DC Current Bidirectional Indicator -  This circuit is handy for battery powered systems.  The circuit is self-powered using a single 3v lithium coin cell.  The current draw is so low that the battery should last for years.  The hobby circuit flashes a red LED when DC current is drawn from the battery and flashes a green LED whenever current flows into the battery.  Two “probe” input wires connect across a section of cable, which acts as a shunt resistor.  A voltage of only 5mv in either direction will trigger a LED indication . . . Hobby Circuit designed by David Johnson P.E.-March, 2011

DC Current Monitor -  Schematic only __ Designed by va3iul

DC Power Wire also Carries Clock or Data -  03/13/98 EDN Design Ideas:  NOTE:  File contains many circuits, please scroll to find this one.  High-side current-sense amplifier, IC 1, offers a simple method of combining low-speed clocks or other signals with dc power in cables between subsystems __ Circuit Design by Mike Hardwick, Decade Engineering, Turner, OR

DDS from 1-60 MHz with built-In Amplifier & variable output level using Analog Devices AD9851 -  Schematic only __ Designed by N2APB, N2CX

Debugging Terminal-Easy -  This LCD terminal provide two modes of operation by selecting jumper J1.  When J1 is open the terminal operate as a normal acsiI display terminal, when J1 is closed the terminal displays the input serial data in hexadecimal format.  This mode is useful for viewing raw data from the serial port output __ Designed by Wichit Sirichote

Decibel Meter -  The circuit below responds to sound pressure levels from about 60 to 70 dB.  The sound is picked up by an 8 ohm speaker, amplified by a transistor stage and one LM324 op-amp section.  You can also use a dynamic microphone but I found the speaker was more sensitive.  The remaining 3 sections of the LM324 quad op-amp are used as __ Designed by Bill Bowden

Decreasing Cost-of-Test with Automatic Test-Pattern Generation -  10/15/01 EDN Design Ideas:  Success in the electronics business hinges on producing high-quality products and using the most cost-effective methods to do so.  As the number of devices on ICs  continues to double every 18 to 24 months, balancing cost and quality becomes increasingly difficult.  Design-for-test and reducing the cost of manufacturing test are key to this balancing act.   __ Circuit Design by Greg Aldrich - October 15, 2001

Decreasing the Cost of Test with Automatic Test Pattern Generation -  08/30/01 EDN Design Ideas:  Success in the electronics business hinges on producing high-quality products and using the most cost-effective methods to do so.  As the number of devices on integrated circuits continues to double every 18 to 24 months, balancing cost and quality has become increasingly difficult.  Design-for-test and reducing the cost of manufacturing test are key to this balancing act.   __ Circuit Design by Greg Aldrich - September 3, 2001

Defining & Testing Dynamic Parameters in High Speed ADCs, Part 1 -  App Note/ 728 / May-05__ Maxim Integrated

Delay Simulator Debugs Communications Equipment -  10/27/94 EDN Design Ideas:   Phone calls over satellite circuits experience a Ľ-sec transmission delay in each direction.  The low-cost circuit (around $20]in Fig 1a simulates this delay and provide as hooks for inserting noise, echo, and other __ Circuit Design by Stan Sasaki, Lake Oswego, OR 10/27/94

Delayed Power using an SCR -  This circuit Creates a Tiny Power Delay to a Circuit.  Read Why I designed it.   __ Designed by G.L. Chemelec

Delayed Pulse Generator -  This circuit generates a short 10ms pulse 15 minutes after a “start” pushbutton switch is activated. . . Circuit by David A. Johnson P.E.-October, 2005

Delta Sigma ADC Bridge Measurement Techniques -  AN96 AN96 features several applications that demonstrate how to take full advantage of Linear Technology's delta sigma ADCs when interfacing to sensors.  in many cases, signal conditioning can be greatly simplified or eliminated completely.  This note explains where it is appropriate to use amplifiers and how to optimize amplifier gain.  Also included__ Linear Technology/Analog Devices

Deogen-Tiny Monitor Tester -  Back in 2000 I built one small embedded device used for repairing of broken PC monitors.  The motivation was to avoid the need of one operational PC near the technician desk used only to generate test rasters, because PCs are usually __ Designed by Radio LocMan

Design for a slightly More expensive Gaussmeter -  This Gaussmeter can use the same Hall effect device as the one above, but what I used was a device from a different company, (a device not recommended by the manufacturer for new designs any longer since availability is not guaranteed, but they only cost $0.89 each!) , with a different sensitivity:  1.3mV/G.   However, the major differences between this Gaussmeter and the one above, is that this unit will give you a positive voltage out for North poles, negative voltages out for South poles, and will read 8.00Vdc for 800Gauss (North pole) , and will read -5.43Vdc for 543Gauss (South pole).  in a modification described, I also added a couple of LEDs to give me a visual indication of North or South pole.   __ Contact rhoadley @ execpc.com

Design High-Performance Pulse Transformers In Easy Stage -  03/16/95  EDN Design Ideas:  raightforward circuit models aid analyzing and designing high-performance pulse transformers.  Practical design becomes easy, once you understand the fundamentals - Both analog and digital designers use pulse transformers to perform a multitude of functio __ Circuit Design by Vincent J Spataro, GEC Marconi Electronic Systems Corp

Designing & Characterizing TRL Fixture Calibration Standards for Device Modeling 11/20/01  -  App Note  Doc #954__ California Eastern Laboratories

Designing & Testing 3GPP W-CDMA User Equipment -  Application Note__ Aligent

Designing & Testing CDMA2000 Base Stations -  Application Note__ Aligent

Designing High-Speed Digital Systems for Logic Analyzer Probing -  Application Note__ Aligent

Designing instrumentationry with RMS/DC converters -  02/01/07  EDN Technical Article: RMS converters rectify average results.  Using rms to measure waveforms furnishes the most accurate amplitude information (Reference 1).  Rectify-and-average schemes, which you usually calibrate to a sine wave, are accurate for only one waveshape, however.  Departures from this waveshape result in pronounced errors.  Although accurate, rms conversion often entails limited bandwidth, restricted range, complexity, and difficult-to-characterize dynamic and static errors.  Recent developments address these issues and also improve accuracy.  Table 1 shows Linear Technology's LTC1966/LTC1967/LTC 1968 device family.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

Designing RF Probe -  make your self simple and heighly useful RF probe.  An essential tool for every home brewer.  __ 

Desktop temperature chamber -  This project was originally conceived as a way to have a small temperature chamber on every engineers bench without the expense of buying a larger than needed commercial unit.  The idea of using a pelter device to make a small chamber was in my head for several years - this project came to fruition when small commercial car coolers came on the market.  I added a PIC  Microprocessor __ Designed by Steve Hageman

Details of a 500 watt HF Dummy load & Power Meter -  This project was published in the April 2004 issue of the Australian magazine "Amateur Radio", and has been designed using parts which are very readily available.  Click here (AR June 2004 Article) to download the PDF file of the article. __ Designed by VK5JST / VK5TR

Details of the VK5JST HF Aerial Analyser- Now with extended coverage down to 200KHz- Plus code changes for the Picaxe 28X1 & new 28X2 chips -  This project was published in the April 2004 issue of the Australian magazine "Amateur Radio", and has been designed using parts which are very readily available.  Click here (AR June 2004 Article) to download the PDF file of the article. __ Designed by VK5JST / VK5TR

Detect & Disconnect Overvoltage -  04/25/96 EDN Design Ideas:  The circuit in Fig.1 protects circuits and systems with power supplies that may exceed safe limits.  One example is small consumer products that use external ac adapters; it's easy to mistakenly plug in the wrong adapter.  Another example is a portable system that uses a rechargeable battery pack.  if the battery pack is absent or fails to open during recharging, a high-compliance charger can deliver excessive voltages to the system __ Circuit Design by Kerry Lacanette, National Semiconductor Corp, Santa Clara, CA

Detect charged bodies with electronic electroscope -  06/28/13  EDN Design Ideas:  Put away your gold leaf and measure charge electronically!  A video demonstrates operation.   __ Circuit Design by Raju Baddi

Detect Clear Fluid -  This circuit detects when a clear fluid is inside a piece of clear plastic tubing.  it can be used for fluid level control and monitoring . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2012

Detect DC Ringing -  08/17/00 EDN Design Ideas:   Ring detection is a common task in telephony-related digital design.  The goal is to sense an ac ringing voltage applied to the telephone line by a central office or PBX (private branch exchange) and then pass an appropriate signal to the µC or µP __ Circuit Design by Jerzy Chrzaszcz, Warsaw Institute of Technology, Poland

Detect Digital RFSignals -  The F.E.D. (Frequency Emissions Detector) will, of course, detect anyone's cell phone, so the detector really responds to just about anybody with more than two pennies to rub together.  Most phones occasionally transmit short bursts to the nearest cell tower, even when the phone isn't in use, so a typical 21st century loiterer will eventually set off the detector.  On the other hand, a deer can stare at it for an hour with no effect.  Let's face it, even most burglars emit digital signals these days.  So, in a sense, the F.  E.  D.  is a human detector.  With that in mind, consider using the output to activate a digital camera or video recorder to capture a record of the prowlers.  A recorded barking dog or, one of my favorites, a recording of police radio traffic will scare off most crooks.  Add some hidden flashing red and blue lights to the police chatter and the culprits will actually run away.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

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Test Equipment:  #'s - A        B - D        E - G
H - L        M - O        P - S        T - Z

 


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