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Tester or Measurement (Instrument) Circuits

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Last Updated: November 30, 2017 10:28 AM
Circuits Designed by Dave Johnson, P.E. :

Bidirectional DC Current 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 A. Johnson P.E.-March, 2011

Brownout Voltage Tester -  I used this circuit years ago to test AC line powered devices under 95vac line voltage conditions.    it has a rating of 250 watts. . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Button Battery Cell Internal Resistance Measurement Circuit -  The open cell voltage of a small silver oxide button cell battery remains very close to 1.5 volts over most of the life of the cell.  However, there is a relationship between battery health and the internal resistance of the cell.   This circuit when used. . . Circuit by David A. 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:

Bidirectional Battery-Current Monitor -  This circuit provides the capability of monitoring current in either direction through the sense resistor.  To allow negative outputs to represent charging current, VEE is connected to a small negative supply.  in single-supply operation (VEE at ground) , the output range may be offset upwards by applying a positive reference __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Bidirectional Current Sense with Separate Charge/Discharge Output -  The LTC6102/LTC6102HV monitor current via the voltage across an external sense resistor (shunt resistor).  internal circuitry converts input voltage to output current, allowing a small sense signal on a large common mode voltage to be translated to a ground-referred signal.  Low DC offset allows the use of very low shunt resistor __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Bidirectional DC Current 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 A. Johnson P.E.-March, 2011

Bidirectional H-Bridge Monitoring with ADC-Friendly Differential Output -  The dual outputs of the LTC6103 can be used individually to provide overload detection, and/or may be taken as a differential pair to provide a bidirectional signal to an analog-to-digital converter (ADC) for example.  Figure 3 shows a typical circuit for a generic H-bridge application.  The power devices may be complementary __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Bidirectional Isolated High-Side Current Sense with 270 V Common-Mode Rejection  -  The input voltage to the AD7170 ADC is converted into an offset binary code at the output of the ADC.  The code is processed in the PC by using the SDP hardware board and LabViEW software.  Figure 5 shows a comparison between the code seen at the output of the ADC recorded by LabViEW and an ideal code calculated based on a perfect system.  __ Analog Devices from the Lab

Bipolar Transistor Tester -  This tester is primarily meant to test bipolar transistors.  it can indicate the type of the transistor as well as identify its base, collector and emitter pins.  The circuit is very...__ Electronics Projects for You

Bistable Flip flop -  Here are two examples of bistable flip flops which can be toggled between states with a single push button.  When the button is pressed, the capacitor connected to the base of the conducting transistor will charge to a slightly higher voltage.  When the button is released, the same capacitor will discharge back to the previous voltage causing the transistor to turn off.  The rising voltage at the collector of the transistor that is turning off causes the opposite transistor to turn on and the circuit remains in a stable state until the next time the button is pressed and released.   __ Designed by Ashish Parab

BJT Tester -  A test circuit for BJT (Bipolar Junction Transistors).  This circuit can measure both small signal hfe and DC current gain hFEof a low to medium power power transistor.  in addition it can measure collector-base and collector-emitter leakage current.  This circuit can also measure hFE at different operating points.  A multimeter can be used at multiple test sockets to make all measurements, or two DC ammeters can be used __ Designed by Andy Collison

Blown-Fuse Indicator Sounds an Alarm -  10-Jul-08 EDN Design Ideas:  A simple blown-fuse-indicator circuit sounds a buzzer and flashes an LED when a fuse blows __ Circuit Design by Vladimir Oleynik, Moscow, Russia

Bluetooth RF Measurement Fundamentals: Application Note 1333-1 -  Application Note__ Aligent

Body Detector -  if someone comes within cooee it will catch 'em! __ SiliconChip

Body Weight Scale Reference Design with Body Composition capability and BLE Connectivity -  This reference design is for a complete body weight scale end equipment with body composition capability featuring TI signal chain, power, and connectivity components. With Ti’s AFE4300 weigh scale/body composition AFE, you can accelerate your body weight scale design or quickly add body composition measurement features to your existing platform. This reference design also includes the full BLE connectivity design for easy interface to BLE enabled smartphones, tablets, etc__ Texas Instruments

Boole helps simplify wiring & save Money -  07/08/04  EDN Design Ideas:  To safely observe the positions of two cylinders, you need two signalsone circuit, X, which is open only when both cylinders are in a safe position (two normally closed switches in parallel], and one circuit, Y, which is closed onl __ Circuit Design by Jean-Bernard Guiot, Mulhouse, France

Boosting Regulator Current -  An outboard pass transistor used to increase the current output of a voltage regulator IC .   __ Designed by Andy Collison

Booze Buster Breath Tester -  Use this fun device to test your soberity, err sobrity, err how much you have had to drink but dont rely on it to drive.__ SiliconChip

Brain Wave Machine -  Humans have been using light and sound to achieve altered states of consciousness for thousands of years.  Primitive cultures used flickering fires and rythmic drumming to induce these altered states.  Today, you can choose from a wide variety of electronic brain-wave machines which use light and/or sound to alter brain-wave activity.  Brain-wave activity ranges from fully awake to deep dreamless sleep.  This activity is categorized into five primary groups: Delta, Theta, Alpha, Beta, and Gamma.   __ Designed by  © Hack Canada

Bridge Reversal Eliminates 1/f Noise & Offset Drift of a Low Noise, Non-Autozeroed, Bipolar Amplifier -  This circuit gives 14nV noise level (or 19 effective bits) over a 10mV span.  Bridge reversal eliminates 1/f noise and offset drift of a low noise, non-autozeroed, bipolar amplifier.  The LTC2440 is a high speed 24-bit No Latency delta sigma ADC with 5ppm iNL and 5μV offset.  it uses proprietary delta-sigma architecture enabling __ Linear Technology/Analog Devices App Note, Jul 8th 2010

Bridge-temperature measurement allows software compensation -  08/17/00 EDN Design Ideas:  Bridge transducers are notoriously temperature-sensitive.  When the temperature changes, almost everything else varies with some parameters increasing and some decreasing.  The TCS (temperature coefficient of span) is generally nega __ Circuit Design by John Wynne, Analog Devices Inc, Limerick, Ireland

Broken-Coil Detector Is Simple Circuit Yet Robust -  03/04/10  EDN Design Ideas:  The circuit in this Design idea was originally designed to detect damaged conveyor belts in the mining industry.  Thin coils are embedded in the conveyor belt.  if the belt suffers damage, it stretches at the affected location, causing one or more coils to break.  The method for detecting the broken coil is to allow a “sensing” coil to magnetically couple with the passing coils in the belt, thus changing the total inductance of the magnetic pair.  The sensing coil is part of an LC oscillator (Figure 1).   __ Circuit Design by Juan Pablo Caram, Santiago, Chile

Brownout Voltage Tester -  I used this circuit years ago to test AC line powered devices under 95vac line voltage conditions.    it has a rating of 250 watts. . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Build 3-State Logic Probe  -  For less than 10 bucks you can build a piece of test gear that you'll find is one of the handiest in your tool kit__ SiliconChip

Build a Digital Audio Millivoltmeter -  Versatile unit indicates signal levels in mV, dBv & dbm.  Want to measure small signals at audio frequencies? Here's a low-cost digital audio millivoltmeter which will allow you to measure audio signals from below 5Hz to above 100kHz.  As well as indicating the level in both millivolts and dBV, it also shows the corresponding dBm level into 600 ohms.__ SiliconChip

Build a Digital Insulation Meter -  Think all your double-insulated power tools are safe, just because they are double insulated? As many have found to their ultimate cost, wear and tear on tools can mean that they become decidedly unsafe.  Here's a meter that will give you back your peace-of-mind ? on tools and many other electrical and electronic devices.__ SiliconChip

Build a G-Force Meter -  Just what are the g forces involved in a balls-to-the-wall lap of Mt Panorama? This little beauty will tell you: instantaneous acceleration, braking, cornering; forwards, backwards, sideways and it's battery operated and completely portable, so you can swap it from car to car! __ SiliconChip

Build a Hearing Loop Level Meter -  Setting the correct signal level and minimising noise are critical factors when setting up a hearing loop.  This easy-to-build tester can display field strength levels over a 27dB range.  Here's how it works, how to build it and how to use it.__ SiliconChip

Build a Hearing Loop Level Meter, Pt.2 -  Last month, we described the circuit for the Hearing Loop Tester and gave the assembly details.  This month, we show how to build a calibration coil and adjust the tester so that it gives accurate results.  We also describe how the unit is used.__ SiliconChip

Build a Hearing Loop Receiver -  This receiver is designed to pick up the signal from a hearing loop and will drive a pair of headphones.  You can use it with a hearing loop you install in your own home or with commercial loops already installed in halls and churches.__ SiliconChip

Build a Magnetic Field Immunity Tester -  You can assemble a precompliance (or even full compliance) magnetic field immunity test system in a few hours using common laboratory instruments, a 100-W audio amplifier, some white PVC Schedule-40 3/4-in.  water pipe, some wood, and a copper or aluminum sheet__ 

Build a Magnetic Stirrer -  Want CONSiSTENTLY GREAT home-brew? Build this magnetic stirrer! __ SiliconChip

Build a Temperature Logger -  Standalone unit can record up to 2048 measurements and display the results on your PC.__ SiliconChip

Build a USB-based GPIB controller -  112/06/05 EDN Design Ideas:  Roll-your-own USB-based instrumentation bus __ Circuit Design by Boštjan Glazar, Marko Jankovec, and Marko Topic, Laboratory of Semiconductor Devices, Ljubljana, Slovenia

Build a Water Level Indicator -  Low-cost circuit lights a LED bargraph to indicate the level in a rainwater tank.__ SiliconChip

Build an Analog Bar Graph Expanded Scale Voltmeter -  An expanded scale voltmeter (ESV) can save your plane.  That may be a strong statement, but it's true.  The crucial radio link that lets you control your plane relies on nickel-cadmium (NIC d) batteries in the transmitter and receiver __ Designed by Stefan Vorketter

Build an Inexpensive Hall Effect Gaussmeter -  Have you ever wanted to find out how strong a magnet really was, or how the strength of the magnetic field varied as you changed the distance from the magnet or the temperature of the magnet, or how well a shield placed in front of the magnet worked?  Voltmeters are fairly inexpensive and easy to find, but where do you purchase a Gaussmeter (also known as a magnetometer).   I built a hand-held Gaussmeter for measuring the polarity and strength of a magnetic field.   it uses a linear Hall effect device and some op-amps and resistors and things from Radio Shack.   __ Designed by Rick Hoadley

Build an Isolated Tee Sampler for a Bird 43 Wattmeter -  Build an isoTee Sampler for the Bird from a blank slug!  __ Designed by Kevin Custer  W3KKC

Build an LED Bargraph Optical Tachometer -  For the electric R/C enthusiast, a tachometer can be a very useful piece of equipment.  When I first built this tach back in 1995, it was essential, as there were very few off-the-shelf electric R/C power systems that just worked.  At that time, you had to experiment with batteries, speed controls or switches, connectors, and wiring, and a tachometer was a tool to help you measure the results. __ Designed by Stefan Vorketter

Build an Ultrasonic Proximity Detector -  Detect objects through ultrasonic sound waves. __ Contact Jameco Electronics

Build this add on Capacitance Meter -  This simple add-on capacitance meter has been specially designed to help you identify capacitors from 1p to 10u.  There has always been a problem identifying capacitors, due.   __ Designed by Collin Mitchell

Build this Negative Ion Detector -  Figure 1 shows a schematic diagram of the ion Detector--a rather simple circuit consisting of three transistors (two PN2907 PNP, and a single PN2222 NPN type) , three resistors, one capacitor, an antenna, a mA meter, and an LED __ Designed by Vincent Vollono

Build your own bypass-capacitor tester -  12/06/01 EDN Design Ideas:  Most circuits use bypass capacitors and can deliver substandard performance if the capacitors have poor pulse characteristics.  Few if any articles cover how to test bypass capacitors for pulse characteristics.  The circuit in Figure 1 tests these characteristics.  it charges the capacitor under test through 100 kU for approximately 1 msec and then discharges it through 10U for a __ Circuit Design by Carl Pugh, Pugh Magnetics, Newark, CA

Build your own Iso-Tee -  Build an iso-Tee from an ordinary T-adapter.   __ Designed by Ted Bleiman K9MDM

Build your own laboratory precision voltage reference -  05/24/07 Video Design ideas-EDN    Mark Thoren, mixed-signal application engineering manager with Linear Technology, demonstrates an amplifier-based Circuit design for a relatively inexpensive precision voltage source.    __ Circuit Design by Mark Thoren, mixed-signal application engineering manager with Linear Technology

Build your own LF/Audio instruments -  Devoted entirely to Amateur radio.   __ Designed by Jan-Martin Nøding

Build your own Q Meter project -  This article appeared in the January/February issue of Amateur Radio (the journal of the Wireless institute of Australia) and is reprinted here for the convenience of others. (Aussies who are not members of the WiA are urged to join our new streamlined national body- it is the only way we have of defending our spectrum allocations against an increasingly greedy mixture of government and private enterprise). __ Designed by VK5JST / VK5TR

Build Youself a Service Monitor? -  A simple deviation monitor circuit used with a scanner receiver.   __ Designed by Tom Alldread VA7TA

Building a Personal Multimeter (Part-1) -  A Digital multimeter is one of the basic equipment used for Test and Measurement in electronics industries.  Nowadays portable handheld multimeters are very useful in giving accurate measurement of voltage, currents, ...__ Electronics Projects for You

Button Battery Cell Internal Resistance Measurement Circuit -  The open cell voltage of a small silver oxide button cell battery remains very close to 1.5 volts over most of the life of the cell.  However, there is a relationship between battery health and the internal resistance of the cell.   This circuit when used. . . Circuit by David A. Johnson P.E.-July, 2006

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


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