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Tester or Measurement (Instrument) Circuits

Test Equipment:  #'s - A        B - D        E - G
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Last Updated: October 24, 2017 02:55 PM
Circuits Designed by Dave Johnson, P.E. :

Circuit tests the self-resonance frequency -  This circuit tests the self-resonance frequency is of an inductor.  During the test, only a few picofarads of parallel capacitance are added to the inductor.  When connected to an oscilloscope and a signal generator, you can measure resonant frequencies . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

Clear Fluid Detector #2 -  Using an ultra low power technique, 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. . . Circuit by David Johnson P.E.-October, 2005

Clip-on AC Current Indicator Circuit -  Several times over the last few years I have received calls from people looking for a simple circuit that would tell them when a sump pump or water well pump motor was running.  These people told me that the electrical circuits that turn on and off . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2004

CMOS Logic Inverter Amplifier characteristics -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers. . . Circuit by David A. Johnson P.E.-February, 2002

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:

Circuit tests power-outage susceptibility -  03/03/97 EDN Design Ideas:  Brief (1 sec or shorter) power outages are common in developing countries and seem to be increasing in the United States.  They are generally nondestructive, so power-protection equipment should not trip and disconnect the load.  Electric motors do not appreciably slow, and electronic equipment can usually ride through the outages on the energy stored in filter capacitors.  As a point of reference, a 10-msec outage makes an incandescent light bulb flicker.  At 100 msec, you can see the bulb go completely dark.  Figure 1 shows a simple circuit for generating brief outages for equipment-susceptibility testing.    __ Circuit Design by Ron Tipton, TDL Electronics, Las Cruces, NM

Circuit tests the self-resonance frequency -  This circuit tests the self-resonance frequency is of an inductor.  During the test, only a few picofarads of parallel capacitance are added to the inductor.  When connected to an oscilloscope and a signal generator, you can measure resonant frequencies . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

Circuit Tests Twisted-Pair Cables -  01/19/12 EDN Design Ideas:  Quickly test a cable containing twisted-wire pairs and detect open or reversed pairs, shorted pairs, and shorts between unrelated pairs.  Using the system shown in Fig 1, you can quickly test a cable containing twisted-wire pairs and detect open or reversed pairs, shorted pairs, and shorts between unrelated pairs.  The tester consists of an active test set that plugs into one end of the cable, and a passive terminator that plugs into the other end. (An RS-449 cable is used as an example.)  __ Circuit Design by Mark D Braunstein, Contel Information Systems, Fairfax, VA

Circuit tests VCOM drivers -  11-Nov-04 EDN Design Ideas:  Flat-panel LCD monitors offer excellent image quality andcompact form factor than CRTs—hence, their steadily increasing popularity.  Unfortunately, the complexity of their manufacturing process makes LCD monitors considerablyexpensive than CRTs.  The amplifier that drives VCOM, the voltage on the backplane of the LCD panel, must be able to drive large capacitive loads, deliver h __ Circuit Design by Soufiane Bendaoud, Analog Devices, San Jose, CA

Circuit translates a law to m law -  05/07/98 EDN Design Ideas:  (NOTE: contains several ideas, scroll down) Two common methods exist to compand voice for transmission through a PCM channel.  in Europe, A law involves converting a 12-bit input signal to an 8-bit encoded output.  in the US, m law involves encoding 13 bits to 8 bits.  You can use a translator to convert from A law to m law (Figure 1).  The converter is asynchronous and requires only an 8-bit A law input to provide an 8-bit m law output. __ Circuit Design by Rolando Herrero, Instituto Tecnológico de Buenos Aires, Argentina

Circuitry for Signal Conditioning and Power Conversion -  Linear Technology AN75 __ Designed by Jim Williams - Mar 1st, 1999

Circuits adds Programmability to Sensor Amplifier -  03/21/02 EDN Design Ideas:  The pressure-sensor amplifier circuit of Figure 1 offers a number of advantages over the traditional approach using the classic three-op-amp instrumentation amplifier.  The circuit can operate from a single supply and uses only two op amps and 1% resistors.  if the reference voltage, VREF, is 0V, the transducer gain for the circuit isTo ensure equal gain for the two ground-referenced volt __ Circuit Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CA

Circuits Monitor & balance large lithium-Ion batteries -  09/03/07  EDN Design Ideas:  Using a microcontroller's built-in ADC to measure cell voltage and temperature, this lithium-ion cell monitor equalizes the cell voltage and signals alarm conditions __ Circuit Design by Daniel Gomez-Ibanez, Woods Hole Oceanographic Institution, Woods Hole, MA

Circuit's RMS output is linearly proportional to temperature over wide range -  it is known that the p-n diode can be the basis of an accurate thermometer for cryogenic temperatures up to about 200°C.  A constant current is maintained through the diode and the voltage across it gives an indication of the temperature.  The magnitude of the constant current is typically chosen small to minimize diode self heating.  The diode voltage falls linearly with temperature making it necessary to have an operational amplifier conditioning circuit for direct readout.  Output calibration is achieved using a voltage reference.    __ Circuit Design by R.O. Ocaya, University of the Free State, Phuthaditjhaba, South Africa

Cistern Overflow Alert System -  The system presented here will electronically monitor cistern (tank that holds water to flush the toilet) overflows that can otherwise cause seepage in the flats below in a multi-storied building.  in...__ Electronics Projects for You

Clamping dissipates minimal power -  03/30/00 EDN Design Ideas:  The circuit in Figure 1 is a quasi-linear regulator.  it functions as a source follower for input voltages greater than a preset level, determined by VR3.  For input voltages lower than the preset level, the pass element, Q2, operates.   PDF contains multiple circuits, scroll to find the one of interest __ Circuit Design by Carlisle Dolland, Allied Signal Aerospace, Torrance, CA

Classic High-Precision Low Side Current Sense -  This configuration is basically a standard non-inverting amplifier.  The op amp used must support common-mode operation at the lower rail and the use of a Zero-Drift type (as shown) provides excellent precision.  The output of this circuit is referenced to the lower Kelvin contact, which could be ground in a single-supply application.  __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Clear Channel Assessment using TI MSP430 & CC2500 Radio -  Smoke Detectors are designed for 3 basic types of system implementations; Standalone, Wireless Connectivity, and Fixed/Wired Connectivity, the first two being battery powered implementations.  Smoke Detectors have 3 main functional blocks; The Sensor and Signal Chain, Processor, and the Communication interface.  Where the processor and communications interface typically are not needed in your very basic standalone detectors __ Designed by Texas Instruments App Notes, 31-Jul-07

Clear Fluid Detector #2 -  Using an ultra low power technique, 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. . . Circuit by David Johnson P.E.-October, 2005

Clear Glass Sensor -  industrial grade clear glass sensor modules are widely available but not within the reach of an average electronics hobbyist.  The simple clear glass sensor circuit can be used for experiment/hobby purposes.  The concept is very simple and is based on a home-made sensor unit comprising one high efficiency ultra bright red LED __ Designed by T.K. Hareendran

Clip-on AC Current Indicator Circuit -  Several times over the last few years I have received calls from people looking for a simple circuit that would tell them when a sump pump or water well pump motor was running.  These people told me that the electrical circuits that turn on and off . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2004

Closed-Caption Decoder -  This is a closed-caption decoder with serial output based on a Microchip PIC 16F628A.  The internal comparators of the PIC 16F628A are used to implement a peak detector and data slicer __ Designed by The hardware was Richard Ottosen, and the firmware was Eric Smith

Cloud Charge Monitor -  The Cloud Charge Monitor is an extremely sensitive device capable of detecting subtle (and not-sosubtle) changes in the accumulated charge overhead.  The device consists of a charge-sensing antenna, a 60 Hz notch filter, a self-zeroing integrator, a signal limiter, and a leakage zero adjustment (circuit / schematic design)  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

CMOS IC 1 kHz Audio Oscillator -  This circuit consists of a CMOS square wave oscillator on a frequency of approximately 1 kHz.  The RC filter, which has a roll-off frequency of 500 Hz, filters the harmonics, providing a sine-wave output.  The oscillator has many uses; sidetone circuits in transmitters and signal injectors for audio tests are just two __ Designed by Peter Parker VK3YE

CMOS IC Makes Low-Cost Digital Potentiometer -  01/18/96 EDN Design Ideas:  A growing trend in the design of electronic equipment is to replace analog knobs used to increase or reduce a continuous signal (such as volume or brightness]with "up" and "down" keys.  However, replacing a low-cost analog potentio __ Circuit Design by Jose Carlos Cossio, Santander, Spain

CMOS Logic Inverter Amplifier characteristics -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers. . . Circuit by David A. Johnson P.E.-February, 2002

Coax connectors make low-cost test pieces -  06/22/00 EDN Design Ideas:  You can readily construct low-cost test pieces using coaxial panel jacks without pc boards or enclosures (Figure 1).  Some engineers and technicians occasionally use this construction technique, but the versatility of the technique is not well-known.  You can design and construct these low-cost test pieces for a variety of passive circuits using tee, pi, el, or bridged-tee networks.    __ Circuit Design by Richard M Kurzrok, RMK Consultants, Queens Village, NY

Cockcroft Walton Diode Voltage Multipliers -  These circuits generate high voltages and can cause dangerous shocks!  Do not build these devices unless you are experienced and qualified to work on high voltage devices. __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Coil Coupled Operation Metal Detector -  A Coil Coupled Operation Metal Detector made from readily obtainable components and using an ordinary medium receiver as a detector.   __ Designed by © Rev. Thomas Scarborough

Cold Activated Switch -  The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees celsius.  A suitable bead type thermistor is found in the Maplin catalogue.  The 100k pot allows this circuit to trigger over a wide range of temperatures.  A slight amount of hysteresis is provided by inclusion of the 270k resistor.  This prevents relay chatter when temperature is near the switching threshold of this circuit __ Designed by Andy Collison

Colour Sensor -  Colour sensor is an interesting project for hobbyists.  The circuit can sense eight colours, i.  e.  blue, green and red (primary colours) ; magenta, yellow and cyan (secondary colours) ; and black and white.  The circuit is based on the fundamentals of optics and digital electronics.  The object whose colour is required to be detected should be placed in front of the system.  The light rays reflected from the object will fall on the three convex lenses which are fixed in front of the three LDRs.  The convex lenses are used to converge light rays.  This helps to increase the sensitivity of__ 

Combination Tachometer, Thermometer & Counter -  inspired by the need to measure dc motor speed and detect overheating, this 68HC908KX8 microcontroller-based circuit displays various statistics on six-digit, eight-segment, numeric LEDs.  See movies of a thermistor in action as well as a reflective or interrupt-based photosensor counting.   __ Contact David Cook

Comparator Detects failed telecomm supplies -  06/22/00 EDN-Design ideas Detects when telecomm power supplys48V output drops below its nominal value, uses an isolated comparator to monitor two48V telecomm supplies ( __ Circuit Design by Richard Markell, Linear Technology Corp, Milpitas, CA

Comparator Detects position of peaks & valleys in a waveform -  05/24/07  EDN Design Ideas:  Simple comparator circuit locates peaks and valleys of a waveform in time __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Comparator uses signal-dependent hysteresis -  EDN Design Ideas:  March 26, 1998    [  NOTE:    FILE
has multiple design, scroll for this one.]  Sometimes, you need to distinguish between two voltages, using some hysteresis in the decision. When the levels of the compared signals vary over a wide range (for example, a few orders of magnitude) , the hysteresis width should vary similarly to ensure a constant ratio between hysteresis width and signal level __ Circuit Design by P Krehlik and L Sliwczynski, University of Mining and Metallurgy, Krakow, Poland

Comparison of Leading Switch/Measure Solutions -  Application Note__ Aligent

Compensate for Four-Wire Sensor Errors -  07/14/11  EDN-Deaign ideas - Measure sensor values and calculate resistance.  Resistive pressure sensors that use two resistive elements and four wires are useful in pressure-monitoring applications.  When the pressure rises, one resistance rises and the other falls.  Accurate measurements with resistive sensors require compensation for losses due to wire resistance, especially when wire lengths are tens of meters.  The compensation method in this Design idea relies on the equal resistance of wires: RL1=RL2=RL3=RL4=RL (Figure 1).   __ Circuit Design by Septimiu Pop and Ioan Ciascai, Technical University of Cluj Napoca, Cluj Napoca, Romania

Compensate for four-wire sensor errors -  Resistive pressure sensors that use two resistive elements and four wires are useful in pressure-monitoring applications. When the pressure rises, one resistance rises and the other falls. Accurate measurements with resistive sensors require compensation for losses due to wire resistance, especially when wire lengths are tens of meters.  __ Designed by Septimiu Pop and Ioan Ciascai, Romania

Complete 12V Automotive Undervoltage, Overvoltage & Reverse-Supply Protection -  The LTC4365 is a unique solution that elegantly and robustly protects sensitive circuits from unpredictably high or negative supply voltages.  The LTC4365 blocks positive voltages as high as 60V and negative voltages as low as –40V.  Only voltages in the safe operating supply range are passed along to the load.  The only external__ Linear Technology/Analog Devices App Note, Sep 19th 2011

Complete 4 mA to 20 mA Loop Powered Field Instrument with HART Interface  -  Digital Data Processing, Algorithm, and Communications All the field instrument digital functions are provided by the ADuCM360 32-bit ARM Cortex™ M3 RiSC processor, with integrated 128 k bytes of nonvolatile flash/EE memory, 8 k bytes of SRAM, and an 11-channel direct memory access (DMA) controller that supports wired (2× SPi, UART, i˛C) communication peripherals.  The demonstration software performs the initialization and configuration, processes data from the analog inputs, controls the analog output, and performs the HART communication__ Analog Devices from the Lab

Complete Type K Thermocouple Measurement System (SPI) with Cold Junction Compensation -  The LTC2484 is ideal for direct digitization of thermocouples and other low voltage output sensors.  The input has a typical offset error of 500nV (2.5μV max) offset drift of 10nV/°C and a noise level of 600nVRMS.  The only signal conditioning is a simple surge protection network.  in any thermocouple meter, the cold junction __ Linear Technology/Analog Devices App Note, Apr 8th 2010

Complete, Low-Cost, Software Programmable Ohmmeter Measures Micro-Ohms -  12/06/12 EDN Design Ideas:  Numerous applications require the measurement of very low resistances, including but not limited to fuse integrity analysis, relay characterization, and superconductor evaluation.   There is a wide range of commercially available equipment designed for this task, but these units are prohibitively expensive and cannot be practically integrated into many applications outside the laboratory.   __ Circuit Design by Moshe Gerstenhaber and Mark Champion, Analog Devices, Wilmington, MA

Components for Ion Chambers -  Radiation Circuits - components used in making an ion chamber __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Computer Voltage & Temperature Monitoring -  The LTC2991 is used to monitor system temperatures, voltages and currents.  Through the i2C serial interface, the eight monitors can individually measure supply voltages and can be paired for differential measurements of current sense resistors or temperature sensing transistors.  Additional measurements include internal temperature __ Linear Technology/Analog Devices App Notes, Sep 7th 2011

Configure a Low-Cost, 9V Battery-Voltage Monitor -  27-Nov-08 EDN Design Ideas:  You can configure an inexpensive, 9V battery-voltage monitor __ Circuit Design by Paul C Florian, McKinney, TX

Connection tester for checking solder joints & other connections -  A low resistance (0.25 4 ohm) continuity tester for checking soldered joints and connections __ Designed by Andy Collison

Consider the Deboo Single-Supply Integrator -  App Note #Di392, July 2002__ Maxim Integrated

Constant Voltage Load Tests Battery Chargers -  04/11/96 EDN Design Ideas:  Testing battery-charging circuits on an actual battery can be difficult, because battery voltage changes during the charging cycle.  The constant-voltage "load box" circuit in Figure 1 provide as a constant-voltage load for a battery-charger circuit independent of the amount of input current.  A constant-voltage load means that the circuit must have a low impedance at all frequencies.  The input impedance of this circuit is approximately 0 ohms at dc and 0.5 ohms at all reasonable input frequencies for charger applications.   __ Circuit Design by Jon Dutra, Linear Technology Corp, Milpitas, CA

Construction metal imager -  05/15/14  EDN Design Ideas:  Build up an image of inductively sensed, hidden metal using the software equivalent of a long time exposure!  My design proposal is to use the LDC1000 to build a metal sensing imager for home and office construction.  My first idea was switching an array of coils and controlling an indicating LED for each.  The cost of even an eight-by-eight array was prohibitive, and would not give a satisfying image.  The second idea was to use a solenoid to activate a marker which would travel through the coil center and mark the surface wherever metal was detected.  Again, cost would be prohibitive, and while satisfactory on a construction site, a homeowner might object to having their walls marked up.   __ Circuit Design by George Mallard

Contactless AC Mains Voltage Detector -  This is a CMOS IC (CD4033) based circuit which can be used to detect presence of AC mains voltage without any electrical contact with the conductor carrying AC current/voltage.  Thus it...__ Electronics Projects for You

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

 


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