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Tester or Measurement (Instrument) Circuits

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Last Updated: November 30, 2017 02:27 PM
Circuits Designed by Dave Johnson, P.E. :

Pot Controlled Variable LED Intensity Circuit -  The circuit below uses power from four rechargeable AA NiMH
cells to drive 3 white LEDs.  A potentiometer varies the duty cycle of a pulse width modulator circuit to vary the intensity of the LEDs from 0% to 100%.  The beauty of the circuit is that when the. . . Circuit by David Johnson P.E.-September, 2009

Power Line Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac.. . . Circuit by David A. Johnson P.E.-July, 2006

Power Loss Beeper -  For some medical equipment it is important for an operator when power is lost to the machine.  The beeper is powered from a 9v battery and requires the machine to have a power switch with a third set of contacts. . . Circuit by Dave Johnson P.E.-March, 1999

Power Reminder Beeper -  This circuit produces a short beep once each minute.  it is powered directly off the 120vac power line to remind you that a device connected to the circuit is turned on.  it is simple enough to be packaged inside a small plastic box. . . Circuit by Dave Johnson P.E.-June, 2000

 

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:

Polarity Detector -  This tester can be used to check the polarity of any power source, and is therefore very useful when installing automotive equipment, alarm systems or anything else you can think of.  Because this circuit is so simple and cheap, even frying one with an over voltage is not a big deal __ Designed by Aaron Cake

Polonium Pen -  Recent events point to the need for a simple device for testing cocktails and beers for excessive quantities of polonium.  The Polonium Pen is a pocket-sized ion chamber with LED readout that is perfect for the job.  Simply hold the Polonium Pen over your drink and, if the LED lights up, order something else __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Polynomial Rotation Accelerates CRC Calculations -  09/08/11  EDN Design Ideas:  Engineers commonly use two methods of CRC (cyclic-redundancy-check) calculations.  One method uses shift registers, and the other uses precalculated CRC values.  The first method shifts the data bit by bit, and, depending on the bit value, a polynomial divideas the bits.  References 1 and 2 explain this method in detail.  You can find assembly-language procedure codes for 8- and 16-bit calculations in references 1, 3, and 4. __ Circuit Design by Josef Valasek, AWOS, Pardubice, Czech Republic

Poor Man's Metal Locator -  it uses just five circuit components, is easy to build and works on the "beat balance" priciple for good sensitivity.__ SiliconChip

Poor Man's Q Meter -  Simple circuit mates with an RF signal generator and multimeter for quick-and-easy "Q" and inductance measurements.__ SiliconChip

Portable Atmospheric Charge Detector -  Schematic + info + pictures __ Designed by Lennie Zink

Portable Crystal Tester -  Acrystal tester is an indispensable tool.  Most electronics projects working with high-frequency equipment utilise crystals to generate frequency for an oscillator.  Using this circuit, you can test and verify the operation...__ Electronics Projects for You

Portable Lightning Detector -  This little device could save your life...__ SiliconChip

Portable oscilloscope -  When I was a poor student, many years ago, I built my own 12V-powered oscilloscope!   __ Designed by Manfred Mornhinweg

Portable Signal Wand -  Flashing lights have varied applications.  For example, travelers can use these as warning beacons on highways to catch the attention of the public in case of an emergency.  Described here is...__ Electronics Projects for You

Position Detectors provide Motor-control logic -  05/24/01 EDN Design Ideas:  in the circuit of Figure 1 , assume that a brush-type dc motor must drive a load back and forth between two endpoints on a lead screw.  Optical sensors determine end of travel, and an SPDT switch selects to which end to send the load.  The sensors themselves supply all the necessary directional logic, and a TRIAC powers the motor with the necessary polarity of half-wave pulses from the 13.   PDF have several circuits, scroll for this one __ Circuit Design by Steve Pomeroy and Russell Hedges, Elgar Corp, San Diego, CA

Position sensing of liquid metal antennas for beam scanning antenna arrays -  03/17/14 - EDN Design Ideas:  High gain beam scanning arrays are usually implemented using phased antenna arrays or mechanically controlled parabolic dishes.  However, the aforementioned technologies are widely known as costly ones.  Recently, a new design of beam scanning arrays has been introduced using the liquid metal technology.  Specifically, the antenna is made of a liquid metal volume that is encapsulated in channels and moved mechanically using a single mechanical pump __ Circuit Design by Ahmad Gheethan-1st prize winner in the TI LDC1000 design contest 2014

Positive Feedback for Isometric Muscle Experiments -  Here I present my 2'nd year university physics project, undertaken while at imperial College, London university. Unlike the 1'st and 3'rd year projects, which were my own proposals, this one was selected in the more usual way from a list of undergraduate projects provided by the physics department. __ Designed by Hans Summers

Pot (digital) Corrects for System Drift -  EDN Design Ideas:  11/10/94    The circuit in Fig 1 looks simple but usually comes as a revelation to designers.  Under control of the system's µP, the digital potentiometer, IC 1, becomes a variable set-point reference that can adapt to the long-term drift of the variable measured.  The digital potentiometer replaces schemes involving A/D and D/A converters (see "Autocalibrator nulls dc offsets, " EDN, June 9, 1994, pg 139, and "infinite-hold circuit zeros out long-term drift, " EDN, March 3, 1994, pg 90).    __ Circuit Design by Mark Rutledge, Xicor Inc, Milpitas, CA

Pot Adjusts LCD's Contrast -  02/04/99 EDN Design Ideas:  NOTE:    Page includes several designs.  Scroll to find this one.  You can use a digitally controlled potentiometer for many purposes.  in this example, you can use the device to regulate the contrast of a standard (such as two lines by 40 characters] LCD.  You can use the circuit in Figure 1 in a portable test system, in which you need to change the contrast of the LCD as a function of the viewing angle.  You choose the contrast setup __ Circuit Design by Jef Collin, CSE Systems, Turnhout, Belgium

Pot Controlled Variable LED Intensity Circuit -  The circuit below uses power from four rechargeable AA NiMH
cells to drive 3 white LEDs.  A potentiometer varies the duty cycle of a pulse width modulator circuit to vary the intensity of the LEDs from 0% to 100%.  The beauty of the circuit is that when the. . . Circuit by David Johnson P.E.-September, 2009

Pot Plant Power -  All plants carry an electric charge relative to the ground.  This charge is more or less constant regardless of the size of the plant a kind of background voltage" in nature.  This electric charge suffuses the entire plant, from its roots to its leaves and fruit.  it was measured between a chrome-plated pin inserted into the plant __ Designed by Rev. Thomas Scarborough

Potentiometer Autonulls OpAmp -  10/22/98 EDN Design Ideas:  Op-amp applications that need the highest possible dc accuracy are generally best served by CMOS chopper-stabilized amplifiers, such as the LTC1050.  But high-speed, low-noise applications may require high-performance rockets, such as the 700-MHz LT1226.  So what to do for applications __ Circuit Design by Stephen Woodward, University Of North Carolina, Chapel Hill, NC

Potentiometer Calibrates Photodiode Amplifier -  EDN-Design ideas -- 06/09/11    Control a potentiometer IC to adjust amplifier gain, compensating for optocoupler output variations. __ Circuit Design by Michael J Gambuzza, General Electric Energy, Billerica, MA

Potentiometer Controls LCD Bias -  03/17/94 EDN Design Ideas:  Designers of pen-based computers can easily relegate some controls that were previously mechanical, such as switches and potentiometers, to on-screen icons.  For example, the circuit in Fig 1 shows one way that digital logic can control the -24V-dc LCD bias using two general-purpose i/O command lines.  The DS-1669 from Dallas Semiconductor __ Circuit Design by Michael Cortopassi, Dauphin Technology, Lombard, IL

Potentiometer controls phase shift -  02/15/96 EDN Design Ideas:  You can use dual, quad, or hex potentiometers to put all phase-shift sections under control of a microprocessor, as in Figure 2.  The DS1806 hex digital .    __ Circuit Design by Rick Downs, Dallas Semiconductor Dallas, TX

Potentiometer Model -  (spice design)  __ Designed by Rick 

Potentiometer Programs & Stabilizes Voltage Reference -  05/30/02 EDN Design Ideas:  The potentiometer portion of a mixed-signal, digitally programmable potentiometer adds variability to an analog circuit, and its controls provide programmability.  You can use a potentiometer in two ways in an analog circuit.  You can use it as a two-terminal variable resistance, or rheostat, or as a three-terminal resistive divider.   / (schematic / circuit added 11/03] __ Circuit Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CA - May 30, 2002

Potentiometer tames current-feedback op Amp -  05/11/00 EDN Design Ideas:  The circuit in Figure 1a includes a potentiometer in series with the inverting input of a current-feedback op amp.  With a voltage-feedback op amp,  __ Circuit Design by Leslie Green, Gould-Nicolet Technologies, Ilford, Essex, UK

Potentiometers Enable Programmable Biquadratic Filter -  07/22/04 EDN Design Ideas:  Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters.  The biquadratic, or biquad, filter is an exception, however.  You can change that filter's corner frequency (ω0], Q, and gain (H] by adjusting the values of three resistors.  For that purpose, the lowpass biquad circuit of Figure 1 includes three digital potentiometers configure __ Circuit Design by Deborah Mancuso and Donald Schelle, Maxim Integrated Products, Sunnyvale, CA

Potentiometers: Frequently Asked Questions -  App Note/ 593 / Nov-05__ Maxim Integrated

Power Conversion, Measurement and Pulse Circuits -  Linear Technology AN113 __ Designed by Jim Williams - Aug 7th, 2007

Power inductor tester -  Measures inductance, saturation current, shows inductor linearity, etc.  Usable with SMPS transformers, inductors, audio components, and some RF and line frequency ones. __ Designed by Manfred Mornhinweg

Power Line Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac.. . . Circuit by David A. Johnson P.E.-July, 2006

Power Loss Beeper -  For some medical equipment it is important for an operator when power is lost to the machine.  The beeper is powered from a 9v battery and requires the machine to have a power switch with a third set of contacts. . . Circuit by Dave Johnson P.E.-March, 1999

Power meter is ±1% accurate -  05/30/02 EDN Design Ideas:  Power meters provide an early warning of thermal overload by monitoring power consumption in high-reliability systems.  Power monitoring is especially suitable for motor controllers, industrial heating systems, and other systems in which the load voltage and current are both variable.  The power meter/controller in Figure 1 uses the principle that power is the product of voltage and current __ Circuit Design by Ken Yang, Maxim Integrated Products, Sunnyvale, CA

Power meter uses low-cost multiplier -  12/23/99 EDN Design Ideas:  A power-meter circuit typically requires either an analog or a digital multiplying circuit.  These circuits can be complex, finicky, or expensive __ Circuit Design by Jeff Kotowski

Power Monitor for AC Lines of 110 to 240 VAC -  May be useful to some persons.   __ Designed by G.L. Chemelec

Power Reminder Beeper -  This circuit produces a short beep once each minute.  it is powered directly off the 120vac power line to remind you that a device connected to the circuit is turned on.  it is simple enough to be packaged inside a small plastic box. . . Circuit by Dave Johnson P.E.-June, 2000

Power Supply Failure Alarm -  Most of the power supply failure indicator circuits need a separate power supply for themselves.  But the alarm circuit presented here needs no additional supply source.  it employs an electrolytic capacitor to store adequate charge, to feed power to the alarm circuit which sounds an alarm for a reasonable duration when the supply fails.__ 

Power Supply Monitor for TTL -  This simple TTL power supply monitor circuit monitors the 5-volt level TTL power line and gives a signal whether the supply voltage is outside or within the necessary range or window.  The heart of the power supply monitor is a__ 

Power transient buffer enables IC & testing -  EDN Design Ideas:  11/10/2014     This DI lets you use a versatile function generator to test a circuit’s response to power transients and noise __ Circuit Design by Carmen Parisi

Power-and VSWR-meters -  Some cheaper "SWR" meters.  The Norwegian Picomatch iI to the left is quite good instrument for 144MHz, believe it is specified quite strict, but some day the instrument people don't like any old instruments __ Designed by Jan-Martin Nřding

Powering an ECG Front End in Battery Powered Patient Monitoring Applications  -  Figure 3 shows a typical screen capture using the evaluation board software with a patient simulator attached to the evaluation board.  , CiRCUiT EVALUATiON AND TEST, Noise Measurements The evaluation board software was used to capture the peak-topeak noise performance of the ECG lead path using the ADAS1000 evaluation board__ Analog Devices from the Lab

Powerline Voltmeter -  Here’s a rather special voltmeter that will let you measure the AC grid voltage and also see very accurately how it fluctuates around its nominal value.  The voltmeter has a measuring range of around 50 V that you can centre around 220 or 240 V to suit your needs.  must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Practical Circuitry for Measurement and Control Problems -  Linear Technology AN61 __ Designed by Jim Williams - Aug 1st, 1994

Practical Temperature Measurements -  Application Note__ Aligent

PRBS generator runs at 1.5 Gbps -  03/29/07  EDN Design Ideas:  FPGA and serializer generate fast sequences to test communications links __ Circuit Design by Lukasz Sliwczynski, AGH University of Science and Technology, Institute of Electronics, Krakow, Poland

Preamp & 330 + MHz Prescaler -  A preamp that drives the CMOS counter input and a divide by 10 prescaler to extend the range __ Designed by Dick Cappels

Precisely measure settling time to 1 ppm -  03/04/10  EDN Technical Article: intense, extensive, and protracted effort yields a measurement circuit with 20-bit resolution.  nstrumentation, function generators, inertial navigation systems, ATE (automatic test equipment) , medical apparatus, and other precision applications now require 18-bit converters.  The resolutions of these converters are so precise that measuring various performance parameters is difficult.  DACs’ dc specifications are relatively easy to verify, but their ac specifications require more sophisticated approaches to produce reliable information.  A DAC’s settling time is the elapsed time from an input code application until the output remains within a specified error band around the final value.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

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


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