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Tester or Measurement (Instrument) Circuits

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

Earthquake Alarm Circuit -  Geophones are dandy motion sensors.  They are metal cans containing a powerful magnet, suspended with springs inside a coil of wire.  The magnet functions as a floating mass.  The slightest vertical motion of the device causes the coil to move relative to . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2005

Either indicates 120 VAC or 240 VAC  -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it. . . Circuit by David A. Johnson P.E.-July, 2006

Electric Field Disturbance Monitor-Alarm Discriminator + Battery Monitor -  This schematic is the alarm discriminator plus the batterry monitor of my "Electric Field Disturbance Monitor".  The system can detect human and animal motion by the electric fields they disturb. . . Circuit by Dave Johnson P.E.-March, 2002

Electric Field Disturbance Monitor-Front End + Power Supply Circuit -  This schematic is the power supply and front-end sections of my field monitor, "Electric Field Disturbance Monitor".  The system can detect human and animal motion by the electric fields they disturb. . . Circuit by David A. Johnson P.E.-March, 2002

Electrical Current Indicator -  I designed this circuit as a simple current indicator for any load ranging from 40 watts to 250 watts.  The circuit turns on a small LED, whenever it detects current flowing to a remote load. . . Circuit by David A. Johnson P.E.-October, 2005

Electrodeless Water Level Monitor -  This is an illustration how a laser could be used to count traffic and measure the speed of each car passing through the sensor area. . . Circuit by Dave Johnson P.E.-July, 2006

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

Does Power Line have 120 VAC or 240 VAC? -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it. . . Circuit by Dave Johnson P.E.-July, 2006

Doorbell Transformer Acts as Simple Circuit Water-Leak Detector -  112/05/09 EDN Design Ideas:  Doorbell transformer acts as a power supply __ Circuit Design by Jeff Tregre, www/BuildingUltimateModels/com, Dallas, TX

Door-Opening Alarm using Hall Sensor -  This simple door-opening alarm uses a hall sensor to produce sound when someone opens the door.  The circuit can be installed at a workshop, office or home for security purposes.__ Electronics Projects for You

Dot/Bar Rx Voltmeter -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Drill Speed Regulator -  A mini-drill machine is always needed in drilling the printed circuit board.  it is usually powered by batteries that limit the drill’s capacity.Using a power supply adaptor with a speed regulator like the one featured here can certainly improve the performance of the drill.  The speed regulator can maintain the speed of the drill no__ 

Drill Speed Controller V2 -  PWM controller derived from a ramp generator and comparator - also drives lamps and other devices __ Contact P. Townshend - EduTek Ltd

DS1669 Digital Potentiometer -  The DS1669 Dallastat™ is a single digital rheostat or potentiometer with access to all three potentiometer terminals.  The potentiometer has 64 wiper positions with equal or linear resistive step sizes.  This device has both positive and negative 8V (max) supply inputs for maximum wiper outputs__ Maxim Integrated

DS18S20 1-Wire Digital Thermometer -  The DS18S20 digital thermometer provides 9-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points.  The DS18S20 communicates over a 1-Wire bus that by definition requires only__ 

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

DTMF RECEIVER -  Today, most telephone equipment use a DTMF receiver IC .  One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits.  The MT8870 is an 18-pin IC .  it is used in telephones and a variety of other applications.  When a proper output is not obtained in projects using this IC , engineers or technicians need to test this IC separately.  A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments.  Here’s a small and handy tester circuit for the DTMF IC .  __ 

DTMF Receiver IC Mt8870 Tester -  Today, most telephone equipment use a DTMF receiver IC .  One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits.  The MT8870 is an 18-pin...__ Electronics Projects for You

Dual Battery Power Manager Increases Run Time by 12% & Cuts Charge Time in Half -  DN277 Design Notes __ Linear Technology/Analog Devices

Dual Comparator -  forms temperature-compensated proximity Detector __ Maxim Integrated

Dual comparators stabilize proximity Detector -  02/16/98 EDN Design Ideas:  (File contains several circuits, scroll to find this one)  __ Circuit Design by Arthur Harrison, US Army Research Laboratory, Adelphi, MD, and Joseph Stern, Maxim Integrated Products, Sunnyvale, CA

Dual Constant-Current Load Tests Low-Current Power Supplies -  06/07/07 EDN Design Ideas:  You can use a simple 9V-battery-powered constant-current load to test small power supplies at various loads.  Today’s small electronic appliances, such as washers, dryers, and stoves, use switched-mode power supplies to replace bulky, heavy, linear-power supplies.  The engineer testing these power supplies, which range in current from 50 mA to 1A, typically uses resistors or standard off-the-shelf electronic loads.  An engineer would employ a variety of high-wattage resistors to verify multiple loading conditions to satisfy a proper design.  Most off-the-shelf electronic loads target an average of 300W.  When measuring 50 to 300 mA, a display is inaccurate; most of them display 0.1A, but accuracy is questionable at that low range.  You can alternatively use the simple dual constant-current-load design in Figure 1, which you can build with inexpensive, common parts.   __ Circuit Design by John Lo

Dual Digital Thermometer -  This application shows how to use the PIC 16F877 to control, and interface with the Dallas DS1820 1-Wire™ Digital Thermometer.  if you missed the LCD connection schematic for these experiments,  __ Designed by © Reynolds Electronics

Dual PSU -  This mini-project came about from building a garden shed - I decided to use an old UPS battery and some spare halogen downlighters for illumination.  But as I researched lead-acid technology, I decided that I needed more sophisticated than a simple switch if I wanted the batteries to survive.   __ Designed by Mark Hennessy

Dual transistor improves current-sense -  08/16/07  EDN Design Ideas:  A two-transistor circuit eliminates variation in output due to temperature __ Circuit Design by Robert Zawislak, PE, Consultant, Palatine, IL

Dual-Coil Relay Driver Uses Only Two MOSFETs -  22-Oct-09 EDN Design Ideas:  Differentially drive relays to minimize power consumption __ Circuit Design by Mehmet Efe Ozbek, PhD, Atilim University, Ankara, Turkey

Dual-Polarity Peak Detector Operates From Single Supply -  05/12/94 EDN Design Ideas:  The circuit in Fig 1  can detect the peak of either positive or negative inputs, yet it operates from a single supply.  The circuit uses two unity-gain amplifiers to monitor the input signal, one an inverting amplifier and the other a noninverting amplifier.  A typical application is driving a VU meter __ Circuit Design by Chester Simpson, National Semiconductor, Santa Clara, CA

Dummy Load for Amplifier Testing -  if you want to test an audio amplifier, here is a compact fan-cooled dummy load that can be used to provide any of the three commonly needed load impedances (4 Ω, 6...__ Electronics Projects for You

DVD Recorder + TV Camera Make Cheap Data Logger -  Sometimes recording the results of a test requires as much ingenuity as designing the product.  Consider a situation which requires the collection of many different variables over a long period of time . . . Hobby Circuit designed by David Johnson P.E.-April, 2005

Dynamic Testing of High Speed ADCs, Part 2 -  App Note/ 729 / Feb-06__ Maxim Integrated

Dynamic-load Determines a battery's internal resistance -  31-Mar-05 EDN Design Ideas:  Meet the challenge of measuring a battery's internal parameters with a nonstatic load approach __ Circuit Design by Jim Williams, Linear Technology Corp, Milpitas, CA

Dynamo Current & Voltage Regulator -  Useful for lovers of older cars, motorcycles and boats. __ Designed by Manfred Mornhinweg

Earthquake Alarm Circuit -  Geophones are dandy motion sensors.  They are metal cans containing a powerful magnet, suspended with springs inside a coil of wire.  The magnet functions as a floating mass.  The slightest vertical motion of the device causes the coil to move relative to . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2005

Earthquake Indicator using Arduino -  An earthquake is an unavoidable and unpredictable natural phenomenon that often causes damage to lives and property.  We cannot fight it but we can stay alert and aware using technology that...__ Electronics Projects for You

Ease Power-Sequence Testing -  07/09/09  EDN Design Ideas:  A low-cost design controls power-up of two power sources.   __ Circuit Design by Goh Hok

Easy Debugging Terminal -  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

Easy Debugging Terminal -  Build a simple 9600 BAUD 8n1 LCD terminal for debugging and testing the projects having RS232C output __ Designed by M Asim Khan  asimkhan @ sat.net.pk

Easy Transistor Tester -  Using this circuit, find out whether a given transistor is good or bad before soldering it.  You can also identify npn and pnp types easily.  The tester gives LED indication of...__ Electronics Projects for You

E-B-C Transistor Pin Identifier -  Tests transistors and diodes for polarity; Simple circuitry - 9V Battery operation __ Contact Flavio Dellepiane, fladello @ tin.it

ECG Amplifier with right leg drive -  Medical and health related electronic circuit diagrams / circuit schematics__ 

Economy radar Detector -  Automotive, car and motorcycle electronic circuit diagrams / circuit schematics__ 

EDA Tools Must Support, Not Suppress, Innovation -  07/23/01  EDN Design Ideas:  One of the most important enablers of innovation is the freedom to explore.  By exploring more options, more "what if" scenarios, a designer can determine the optimum design, find more obscure bugs and discover new ways of delivering more functionality and higher performance.  This is the key to innovation.  However, with today's time-to-market pressures, the freedom to explore is a luxury that not all system-on-a-chip (SOC) designers can afford.  Yet, thoroughly verifying designs is a must.  SOC designers must test as much of the chip as possible before going to market, but rarely do they have the freedom to leverage the verification process to improve hardware and software designs.   __ Circuit Design by Mike Tsai

E-H 201C Electrometer schematic -  Circuit Only__ 

E-H 215 RL Electrometer schematic -  Circuit Only__ 

EICO 1050 Battery Eliminator -  Schematic Only__ 

EICO 250 AF VTVM -  Schematic Only__ 

EICO 315 RF/AF Signal generator -  Schematic Only__ 

EICO 488 Electronic Switch -  Schematic Only__ 

EICO 680 transistor Tester manual w/schematic -  Circuit Only __ Designed by EICO

Eight Decade Current Sensing Log Amplifier -  The low pA's of bias current of CMOS amplifiers make them suitable for high input impedance current sensing applications.  By taking advantage of the logarithmic relationship of a transistor base-emitter voltage to it's collector current a very wide range of measured input current can be converted to a voltage.  in this circuit the input current can span six decades from 10nA to 10mA.  The positive tempco resistor compensates for the 0.3%/C tempco of the logging transistors scale factor coefficient (kT/q) __ Linear Technology/Analog Devices App Note, Mar 16, 2010

Eight LEDs Make a 100-Division Voltmeter -  09/22/11  EDN Design Ideas:  Use a counter IC to drive two sets of four LEDs.  The circuit in this Design idea makes a voltmeter that reads to 0.99V.  The idea uses a counter IC to drive two sets of four LEDs (Figure 1).  Each of these two sets represents a BCD (binary-coded-decimal) value.  With all of the LEDs off, the voltmeter reads 0V.  With all of the LEDs on, the reading is 0.99V.  Op amp IC 1A generates a predictable voltage ramp. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune University, Maharashtra, India

Eight Simple Circuit power supplies for your workbench (mainly vacuum tube based) -  The power transformer is what isolates the output terminals from the line and makes it safe.  if you can't find a particular transformer there are several alternatives among the circuits.  A transformer you already have or one you can get may determine which circuit you build.  The circuits that use a 5Y3 rectifier tube require a transformer with a 5 volt 2 amp winding for the tube's filament.  if you can't find or don't have a transformer with a 5 volt winding one of the 6AX5 circuits may be for you. __ Designed by Max Robinson

Got Designs?
Please eMail
if you want me to link to and/or post your original design.  Thanks.

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

 


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