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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 13, 2017 03:11 AM
Circuits Designed by Dave Johnson, P.E. :

10 Turn Pot Forms Frequency Readout -  Lets say you are designing a signal generator for a test fixture.  To adjust the frequency you would like to use a ten turn pot with a nice dial mechanism attached as a frequency display.  However, a display range of 0 to 9.99 would be impractical since . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2008

120 VAC / 240 VAC Indicator -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

120VAC Under Voltage Tester -  Using a cheap 24vac transformer, this circuit can test a product under low 95vac conditions.    With the components show, it has a rating of 250 watts max.. . . Circuit by David Johnson P.E.-July, 2006

12v Battery Voltage Monitor-Expanded Scale  -  The circuit below expands the battery voltage monitoring scale for a 12v battery so a more accurate voltage reading can be made.  The numbers printed onto the face of a standard 0v to 5v meter are changed so the scale ranges from 10v to 15v . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2005

12v Cooling Fan Thermostat -  This circuit will turn on a 12v DC powered cooling fan when the air temperature reaches a certain high temperature and will keep the fan turned on until the temperature drops below a second lower level.  Both the high and low temperatures are both adjustable. . . Circuit by Dave Johnson P.E.-February, 2011

12v Lamp Current Indicator -  This circuit turns on a LED indictor light whenever DC current flows into a 12v lamp. . . 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:

$5 junkbox Determines Phase Sequence  -  04/23/98 EDN Design Ideas:  NOTE: File contains multiple circuits scroll to find this circuit.  Have you ever wondered which way a blower motor is going to turn when you plug it into anor socket, or have you ever inherited  task of modifying three-phase wiring in your plant?    __ Circuit Design by Hugh Adams, Fort Walton Beach, FL

C Controls Digital Potentiometer -  10/08/98 EDN Design Ideas:  Many digitally controlled potentiometers (for example, the LM1971/02/3 from National Semiconductor, www.national.com] incorporate a three-wire serial digital interface, using data, clock, and enable lines.  in Figure 1, the potentiometer's nomenclature for these lines is Data-in.  Several circuits in article, scroll to find this one.      __ Circuit Design by Lukasz Sliwczynski, University Of Mining And Metallurgy, Krakow, Poland

C measures High-frequency signals -  03/02/98 EDN Design Ideas:  (File contains many circuits, please scroll to find this one) To measure a high-frequency signal using an 8-bit C, the time period of the measured frequency must be relatively close to the internal clock of the C.  For example, if the internal clock period is 1 sec, then.   __ Circuit Design by Stan D'Souza, Microchip Technology Inc, Chandler, AZ

C multiplexes six digital potentiometers -  05/11/00 EDN Design Ideas:  in Figure 1's circuit, a C lets you adjust as many as six digital potentiometers.  Like mechanical potentiometers, digital potentiometers can adjust regulator outputs or speaker volumes and act as rheostats.  Available in resistances of 50, 100, and 200 kV, they let you throw away your mechanical potentiometers and the little flat-headed screwdrivers that go with them.   __ Circuit Design by Ted Salazar, Maxim Integrated Products, Sunnyvale, CA

0 to 60 MHz Spectrum Analyzer-WB5IPM -  Schematic only __ Designed by va3iul

0-100 MHz Spectrum Analyzer Tracking Generator-W6URH -  Schematic only __ Designed by va3iul

0-100C Temperature Detector -  Heres a temperature monitoring system capable of remote temperature reading without transmission losses in the conditioning circuit.  The IC AD590 (IC 4) is used as a temperature transducer.  This semiconductor transducer provides ...__ Electronics Projects for You

0-500MHZ LM3914 RF Power Meter -  RF Measurement has been an expensive work so far the cost f measuring instruments are concerned.  Although, the other project, PM2, is hot favorite among radio amateurs for RF Measurement, I wanted something smaller __ Designed by Dinesh Gajjar, VU2F0

1 chip Detects optical interruptions -  03/01/01  EDN Design Ideas:  Setting up a light beam and detector to count objects on a conveyer belt, sense security intrusions, or drive a tachometer is simple.  However, the task is no longer trivial if you add ambient light or multiple beams, limit optical power, or extend the dis __ Circuit Design by Frederick M Baumgartner, FM Broadcast Services, Parker, CO

1 GHz Spectrum Analyzer Front-End -  Schematic only __ Designed by va3iul

1 GHz Test Oscillator BFP450 -  Schematic only __ Designed by va3iul

1 Hex-Inverter IC Makes Four Test Gadgets -  07/30/12  EDN Design Ideas:  This can be a fun project for students and seasoned engineers alike.   __ Circuit Design by Raju Baddi

1 IC forms inexpensive inductance tester -  08/02/07  EDN Design Ideas:  A simple Pierce oscillator measures the inductance of a device under test __ Circuit Design by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy

1 switch controls digital potentiometer -  09/19/02  EDN Design Ideas:  This design idea     is an evolution and simplification of another (Figure 1, Reference 1].  Replacing the three inverted-input NOR gates with their logical equivalents, positive-input NAND gates, makes these three gate symbols consistent __ Circuit Design by Jim Bach, Delphi Delco Electronics Systems, Kokomo, IN

1 wire bus powers water level sensor -  02/15/00 EDN Design Ideas:  remotely monitor the level of liquid water in a vessel such as a swimming pool __ Circuit Design by Dale Litwhiler, Lockheed Martin, Newtown, PA

1.5v Battery Meter -  simple but effective way of testing 1.5 volt cells __ Contact P. Townshend - EduTek Ltd

1.5V, 7A Bus Termination -  09/14/95  EDN Design Ideas:  Some of the newest high-performance processors require a 1.5V bus terminator that can source currents as high as 7A.  This terminator requires a very fast transient response, because the device must react to high peak-current changes that have extremely fa __ Circuit Design by Chester Simpson and Mineo Yamatake, National Semiconductor, Santa Clara, CA

10 Hints for Making Better Network Analyzer Measurements -  Application Note__ Aligent

10 Hz to 16 MHz, DDS based Low frequency scalar network analyzer with PC control -  This demonstration project built on a 16 MHz DDS source and a A and B detectors to make a full stimulus - response network analyzer that can be built by nearly anyone at a fraction of the cost of a commercial unit.  This was a very popular project that showed just how much could be done by a determined Homebrewer __ Designed by Steve Hageman

10 Turn Pot Forms Frequency Readout -  Lets say you are designing a signal generator for a test fixture.  To adjust the frequency you would like to use a ten turn pot with a nice dial mechanism attached as a frequency display.  However, a display range of 0 to 9.99 would be impractical since . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2008

10C to 40C Thermistor Thermometer -  The LT1789 is a micropower, precision instrumentation amplifiers that are optimized for single supply operation from 2.2V to 36V.  The quiescent current is 95μA max, the inputs common mode to ground and the output swings within 110mV of ground.  The gain is set with a single external resistor for a gain range of 1 to 1000 for__ Linear Technology/Analog Devices App Note, Mar 30th 2010

100 MHz Spectrum Analyzer-W6URH -  Schematic only __ Designed by va3iul

1000:1 EHT Probe -  Do you need to measure the EHT voltage in a CRT-based scope, computer monitor or TV receiver, or perhaps in a photocopier, laser printer or microwave oven? You'll need an EHT probe to suit your digital multimeter (DMM) to do this and you'll find they are pretty pricey.  Not to worry though, because here's one you can build for less than $40.__ SiliconChip

10Hz-100kHz D.D.S. Function Generator -  The presented project is a function generator for sinusoidal and square signals production.  The output frequency covers the range from 10 Hz to 100 KHz with a step of 2 Hz.  The waveform synthesis is based on the D.  D.  S.  technique (Direct Digital Synthesis) and the output frequency is selected through a microcomputer with an embedded thumb wheel keyboard. 
 __ Designed by George Vastianos

10Hz-1300MHz Frequency Meter -  Universal VHF/ UHF frequency meter __ Designed by YO5OFH, Csaba Gajdos

12 Volt Battery Backup -  This simple project makes a nice companion to power units in cas of power outages, especially caused by severe weather __ Designed by Lennie Zink

12 Volt Battery Charge Monitor -  Here is a battery monitor circuit which disconnects the load when the battery is discharged, preventing a deep discharge which could cause permanent battery damage.  The battery is automatically reconnected when a battery charger or other DC source is connected across the load.  Select a relay which requires less than 100ma coil current and with contacts capable of handling the load and charging __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

12 Volt Battery Low Indicator LM741 -  Plans for a battery low indicator for a 12 Volt battery using an LM741 operational amplifier.   __ Designed by REUK-Renewable Energy UK website

12 volt battery Monitor -  R1 controls the trip-point of the circuit.  when the voltage falls below the trip-point, the LED lights.  adjust it to the desired level.  to use this circuit to monitor a 6v battery, substitute D1 for a 3.3  volt zener diode and adjust R1 accordingly.   __ Designed by Andy Wilson

12 Volt Car Battery Meter -  A 10 LED calibrated voltmeter from 11-15 volts, needs no extra battery __ Contact P. Townshend - EduTek Ltd

12 Volt Differential Temperature Controller -  for hot water and hot air system control __ Designed by G. Forrest Cook

12 Volt Lead Acid Battery Monitor -  This simple circuit makes it posible to monitor the charging process to a higher level.  if you need more information then check out the LM3914 Datasheet. 
Final adjustsments are simple and the only thing needed is a digital voltmeter for the necessary accuracy __ Designed by Jan Hamer

12 Volt Toilet Tank Refiller -  A flushing toilet is something that most city dwellers take for granted, but it can be a luxury for those who live away from utility water and electricity.  This circuit provides on-off pump switching for a small 12 Volt pump that is used to fill a toilet tank from an external rain water collection cistern.  The 12 Volt power comes from a small solar power system.  The cistern is located at ground level, so the pump is required to move the water up to the toilet tank.   __ Designed by G. Forrest Cook

120 VAC / 240 VAC Indicator -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

120VAC Under Voltage Tester -  Using a cheap 24vac transformer, this circuit can test a product under low 95vac conditions.    With the components show, it has a rating of 250 watts max.. . . Circuit by David Johnson P.E.-July, 2006

120W Supply Monitor Includes ICC of LT2940 -  The LT2940 measures a high side current and a differential voltage, multiplies them and outputs a current proportional to instantaneous power.  Bidirectional high side currents and bipolar voltage differences are correctly handled by the four-quadrant multiplier and push-pull output stage, which allows the LT2940 to indicate__ Linear Technology/Analog Devices App Note, Apr 26th 2010

12-Bit, 4-20mA Loop-Powered Thermocouple Measurement System using ARM Cortex-M3  -  Required software for the J-Link OB is included in the software installation.  The source code used to test the circuit can be downloaded as a zip file from the ADuCM360 product page.  The source code uses the function libraries provided with the example code.  __ Analog Devices from the Lab

12V 1.5A Buck Regulator with Virtual Remote Sense -  The LT4180 solves the problem of providing tight load regulation over long, highly resistive cables without requiring an additional pair of remote sense wires.  This Virtual Remote Sense device continuously interrogates the line impedance and corrects the power supply output voltage via its feedback loop to maintain a steady voltage at the load regardless of current changes__ Linear Technology/Analog Devices App Note, Jun 7th 2010

12V 20-120W Solar Panel Simulator -  How do you test or develop a solar charge controller such as the unit described in SiLIC ON CHiP last month? You could use a solar panel but then you are at the whim of the weather and time of day.  Also you would need several panels of different sizes to test it properly.  This device solves all those problems.__ SiliconChip

12v Battery Capacity Tester -  An application for the above mentioned LV Disconnect circuit that makes testing the amp-hour capacity of batteries a breeze.   __ Designed by Burton Lang

12V battery level indicator for car batteries -  This kit measures battery voltage.  The red LED (closest to the IC ) indicates a low status - 11.5Volts or less.  The yellow LED indicates 50% charge - 12.0V.  The green LED indicates 12.6V or full charge.  This kit also measures the charging status.  Turn the charging system on - or start the vehicle.  The red LED (at the extreme end from IC ) indicates overcharge - 15.5V.  The green LED indicates maximum charge voltage - 14.5V.  The yellow LED indicates normal charging voltage - 13.2V.  __ CdS Electronic

12v Battery Voltage Monitor-Expanded Scale  -  The circuit below expands the battery voltage monitoring scale for a 12v battery so a more accurate voltage reading can be made.  The numbers printed onto the face of a standard 0v to 5v meter are changed so the scale ranges from 10v to 15v . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2005

12v Cooling Fan Thermostat -  This circuit will turn on a 12v DC powered cooling fan when the air temperature reaches a certain high temperature and will keep the fan turned on until the temperature drops below a second lower level.  Both the high and low temperatures are both adjustable. . . Circuit by Dave Johnson P.E.-February, 2011

12v Lamp Current Indicator -  This circuit turns on a LED indictor light whenever DC current flows into a 12v lamp. . . Circuit by David A. Johnson P.E.-July, 2006

12V Lead-Acid Battery Monitor using LM3914 -  This simple circuit makes it posible to monitor the charging process to a higher level.  if you need more information then check out the LM3914 Datasheet.  Final adjustsments are simple and the only thing needed is a digital voltmeter for the necessary accuracy.  Connect an input voltage of 12.65 volt between the positive and negative poles and adjust the 10K trimmer potentiometer until LED 10 lights up.  Lower the voltage and in sequence all other LEDs will light up.  Check that LED 1 lights up at approximately 11.89 volts.   __ Designed by with permission of Jan Hamer

12V LED Battery Voltage Monitor -  The BVM1 kit can be used to monitor the voltage of a 12 Volt battery.  it features ten ultra-bright LEDs in five vivid colors for quick battery voltage measurement.  One of the LEDs will briefly blink on every 1.25 seconds, keeping average power consumption low.  The display is readable from dark to full sunlight.  A switch-controlled low voltage beeper is included, this provides a warning when the battery voltage drops below a preset value and can help to prevent excessive discharge.   __ Designed by Solar Orbit Kit

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

 


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