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

36-Hour Watchdog Timer -  A watchdog timer is often used in computer systems to detect when a computer is hung up and is no longer running properly.  if it does become locked up and is not able to supply a reset pulse to the circuit within a defined time frame the timer times out a. . . Circuit by Dave Johnson P.E.-April, 2010

3mw Laser Test-20Mhz VCSEL -  This circuit takes advantage of some new vertical cavity surface emitting lasers (VCSEL) that don’t require light output control circuits.  The circuit shows how to drive the device from a single high speed CMOS IC . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

4 to 20ma Current Loop Senses Temperature -  I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room.  The circuit uses a very robust current loop method.  it uses a highly accurate semiconductor temperature sensor . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2000

40Khz Laser Burst Detector -  This circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen.  it was used as part of a firearm training system.  it generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst,. . . Circuit by Dave Johnson P.E.-June, 2000

40Khz LED Test Signal Generator -  This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses.  The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals. . . Circuit by David A. Johnson P.E.-February, 2002

40KHz Light Receiver Front-End Circuit -  This circuit uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network.  it is very stable and very sensitive.  This hobby circuit shown has the potential for a conversion factor of 10 volts per microwatt at 900nm.  I included a simple JFET post-amplifier with a gain of about 20.. . . Circuit by David 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:

220/230VAC Input 12VAC Output 100VA Max Halogen Converter -  Fully Assembled and Tested demo board CD including datasheets, App Note  And ballast design software Features: Short Circuit and Overload Protection, Fully dimmable with all dimmer types, Compensated Load Regulation, Over temperature shutdown, EMI Filter__ International Rectifier

220v Live Wire Scanner -  This simple circuit lets you scan a 220V live wire.  The clock input of the IC is connected to a wire, which acts as the sensor.  Here, we have used 10cm...__ Electronics Projects for You

220V live Wire-In-Wall scanner -  This little circuit will help you to scan line of a 220V live wire in wall.  FET gate is connected to a capacitive metal sensor (which is usually a simple metal plate).  When you hold sensor close to wall, LED will indicate current flow around where it detects wire.  Works on 9VDC __ Designed by Peter Jakab, Electrical Engineer, Engineer of Informatics

220V mains Monitor -  With this circuit you will be able to monitor the quality of the mains.  There are 4 distinct sections, each supervising a parameter pertinent to the quality of the supply line.  The noise section consists of a 50Hz filter and a speaker where you will hear the noise present on the line.  The bicolor LED should be adjusted for the least light with the 5k pot and gives a visual indication__ 

2-250 MHz Synthesized, 1 Hz Resolution, PC controlled source -  A Homebrew network analyzer, with full calibration!  (Featured in QEX)  __ Designed by Steve Hageman

24-Bit ADC Measures from DC to Daylight -  DN219 Design Notes__ Linear Technology/Analog Devices

25-kV generator tests insulation -  06/05/98 EDN Design Ideas:  (Scroll to find this circuit) To generate high voltages with proper insulation between the "hot node" and the rest of the circuitry, a car ignition coil can function in place of a high-voltage transformer.  These coils have voltage ratings of approximately 20 kV, so you can use them to produce voltages __ Circuit Design by Lukasz Sliwczynski and Przemyslaw Krehlik, University of Mining and Metallurgy, Krakow, Poland

28V Power to Frequency Converter -  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

28V Vehicle Application with Reverse Voltage Protection -  The LTC4366 surge stopper protects loads from high voltage transients.  By controlling the gate of an external N-channel MOSFET, the LTC4366 regulates the output during an overvoltage transient.  The load may remain operational while the overvoltage is dropped across the MOSFET.  Placing a resistor in the return line isolates the LTC4366 and allows it to float up with the supply; therefore, the upper limit on the output voltage depends only on the availability of high valued resistors and MOSFET ratings.  __ Linear Technology/Analog Devices App Note, Jan 16th 2012

2-Terminal Temperature-to-Current Thermometer Suitable for Use at the End of Long Wire Runs -  By adding the LT3092 to a thermistor kit along with three 0.1% accuracy resistors and one final trim, a very accurate 2-terminal temperature-to-current converter can be built.  This circuit measures 700μA operating current at 0°C, dropping by 2μA every degree until 100°C, at which point the current measures 500μA.  The obvious __ Linear Technology/Analog Devices App Note, Mar 16th 2011

2-Wire Thermistor 0°C to 100°C Temperature Transducer with 4mA to 20mA Output -  The LTC1040 is a monolithic CMOS dual comparator manufactured using Linear Technology’s enhanced LTCMOS TM silicon gate process.  Extremely low operating power levels are achieved by internally switching the comparator ON for short periods of time.  The CMOS output logic holds the output information continuously while not consuming __ Linear Technology/Analog Devices App Note, Mar 30th 2010

3 Digits Digital Volt Meter with PIC16F676 -  This is simple 3-digits digital volt meter.  PIC 16F676 used to read analog signal (voltage) and display the value on 3-digits 7-segment.  You can apply similar principles to measure DC current with parallel R shunt.  __ 

3 in one tester (audio, tone generator, diode/circuit tester) -  Ham Radio - Schematic only, no circuit description __ Designed by Guy Roels ON6MU

3.3V converter Delivers 3W from Li-Ion battery -  11/05/98 EDN-Design ideas (Several circuits here, scroll to find this one) Lithium-ion batteries are rapidly gaining popularity in portable applications because of their superior energy density, low self-discharge rate, and high cell voltage.  When you use one Li-ion battery to power a 3.3V DC/DC converter; however, you encounter a problem, because the battery voltage.    __ Circuit Design by David Salerno, Unitrode Corp, Merrimack, NH

3.3V lithium-cell supply requires one inductor -  08/05/99 EDN Design Ideas:  Because of growing popularity of lithium-ion (Li-ion) batteries and 3.3 V power supplies, portable-equipment designers must often create a 3.3 V supply that a single Li-ion cell can power __ Circuit Design by Matt Schindler and Jay Scolio, Maxim Integrated Products, Sunnyvale, CA

3.3V/10mA Regulator from a 4mA to 20mA Loop -  This circuit is a 3.3 V/10mA regulator that extracts its power from a 4mA to 20mA loop.  This circuit demonstrates how an LTC1474/LTC1475-based regulator is easily optimized for such low current applications.  The 2W sense resistor limits the peak inductor current to 40mA to minimize current ripple and provide good efficiency __ Linear Technology/Analog Devices App Note, Mar 16th 2011

3.6 Volt (cell phone) LED Battery Meter -  This is a similar circuit to the above and provides a 4 LED bar graph indicating the voltage of a common 3.6 volt Lithium - ion recharable cell phone battery.  The reference voltage is provided by a TL431 programmable voltage source which is set to 3.9 volts where the TL431 connects to the 1K resistor.  The lower reference for the LED at pin 14 is set with the 5K adjustable resistor.   __ Designed by Bill Bowden

30 Meter QRP Transmitter for Morse Code -  This transmitters' intended purpose is for morse-code only in30 meter band (Tony van Roon's 10Mhz).  it is a low-power QRP type and needs to be connected to your existing tranceiver.  harmonic rejections onprototype were measured at 40dB on 20Mhz and 50dB on 30Mhz __ Designed by Tony van Roon  VA3AVR

30 W Digital Wattmeter for RF (0-500 MHz) -  This project will explain how I build my new wattmeter.  This watt meter will be able to measure power from 300 nW to 30 WAT (0-500 MHz).  This wattmeter is based up on a dummy load of 50 ohm which can handle 50 W.  The measurement will be displayed __ Designed by Radio LocMan

300 MHz  Prescaler & 30 MHz preamp for Little More Serious Frequency Meter  -  A preamp that drives the CMOS counter input and a divide by 10 prescaler to extend the range __ Designed by Dick Cappels

300ma DC-to-AC Converter -  This circuit was used to provide battery backup to a device that had an AC (output) wall transformer.  Due toquasi-sine-wave output and imprecise 60Hz output frequency, some devices might not work properly.  Peak output isDC input voltage minus about 20  __ Designed by Andrew R. Morris

30W Digital RF Wattmeter -  This project will explain how I build my new wattmeter.  This watt meter will be able to measure power from 300nW to 30W @ (0-500MHz).  This wattmeter is based up on a dummy load of 50 ohm which can handle 50W.  The measurement will be displayed in Watt on a 2x16 Char display.__ 

3-12 MHz Signal Generator -  Schematic Only __ Designed by Peter Parker VK3YE

35kHz Magnetic-Radiation Remote-Control -  Short-range 35KHz operation, single-channel units; Simple circuitry, no outer antennas required __ Contact Flavio Dellepiane, fladello @ tin.it

36-Hour Watchdog Timer -  A watchdog timer is often used in computer systems to detect when a computer is hung up and is no longer running properly.  if it does become locked up and is not able to supply a reset pulse to the circuit within a defined time frame the timer times out a. . . Circuit by Dave Johnson P.E.-April, 2010

3-Digit DVM Voltmeter -  Uses 3161, CA3162 IC s.  __ 

3-Digit Volt/ Amper Meter -  Even if the digital multimeters have dominated in a lot of applications, in the measurement, exist the need for existence of instruments of clue in various appliances, voltage and current, as in power supply or elsewhere.  The circuits that give make this precisely the work, measure the voltage in terminal a circuit and the current that passes in his.  The circuit does not present particular difficulties for somebody that has a small experience.  The two circuits are the himself, with a small difference only in their input, when they have they measure voltage or current and in connection that concern decimal point.  __ 

3mw Laser Test-20Mhz VCSEL -  This circuit takes advantage of some new vertical cavity surface emitting lasers (VCSEL) that don’t require light output control circuits.  The circuit shows how to drive the device from a single high speed CMOS IC . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

3rd Harmonic Distortion Meter for Measuring the Quality Of AC Supply -  The 3rd harmonic distortion meter has been designed for measuring the quality of AC supply.  The meter is built with a PIC 18F2550 project board and the full wave rectifier front-end circuit.  The AC power line, 220VAC is measured through the step down isolation transformer.  The input signal to the 10-bit ADC is full wave rectified.  The software performs DFT calculation finding the amplitude of the fundamental frequency and the 3rd harmonic.  The distortion is computed by the ratio of the amplitude of the 3rd harmonic to the fundamental frequency.   __ Designed by Wichit Sirichote

4 mA-to-20 mA Loop-Powered Temperature Monitor using the ADuC7060/ADuC7061 Precision Analog Microcontroller  -  This ADC measurement can be used as feedback for the PWM control software to adjust the 4 mA-to-20 mA current setting.  , The primary ADC of the ADuC7060/ADuC7061 measures the voltage across the RTD__ Analog Devices from the Lab

4 to 20ma Current Loop Senses Temperature -  I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room.  The circuit uses a very robust current loop method.  it uses a highly accurate semiconductor temperature sensor . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2000

40 Meter Direct Conversion Receiver -  Using the circuit of direct-conversion receiver described here, one can listen to amateur radio QSO signals in CW as well as in SSB mode in the 40-metreband.  The circuit makes use.  __ 

40 MHz Frequency meter on ATmega16 -  This article shows how to build a small, cheap and simple frequency meter, without any fancy, out of reach components.  The simple proposed design can measure frequencies up to 40 Mhz with errors below 1%!  This degree of precision will be more than__ 

40 Segment LED S-Meter -  Provide your radio with a very string signal, then adjust the HiGH LEVEL pot to the threshold of illuminating the last LED (all LEDs on).  Remove the signal completely, then adjust the LOW LEVEL pot to the threshold of no LEDs illuminated.  if your radio's S-meter output is greater than 5 volts, you mau wish to replace the HiGH LEVEL pot with a 10K resistor, and provide pin 6 of the right-most 3914 with the cathode of a 6.1 volt zener diode, pulled up to 13 volts with a 1K resistor.  The anode should be connected to ground.  You may use a higher voltage zener if necessary.   __ Designed by N6ZAV Marty Mitchell

4000 series CMOS Logic ICs -  There are many ICs  in the 4000 series and this page only covers a selection, concentrating on the most useful gates, counters, decoders and display drivers.  For each IC there is a diagram showing the pin arrangement and brief notes explain the function of the pins where necessary.  The notes also explain if the IC 's properties__ 

40kHz IR Tester -  Use this circuit to test if the light coming from your 40khz IR emitter is really emitting the right frequency.  The schematic says to use a GP1U5X IR module, but probably any 40khz detector module will work.   __ Designed by Andy Wilson

40Khz Laser Burst Detector -  This circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen.  it was used as part of a firearm training system.  it generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst,. . . Circuit by Dave Johnson P.E.-June, 2000

40Khz LED Test Signal Generator -  This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses.  The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals. . . Circuit by David A. Johnson P.E.-February, 2002

40KHz Light Receiver Front-End Circuit -  This circuit uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network.  it is very stable and very sensitive.  This hobby circuit shown has the potential for a conversion factor of 10 volts per microwatt at 900nm.  I included a simple JFET post-amplifier with a gain of about 20.. . . Circuit by David Johnson P.E.-June, 2000

40MHz 32 Channel Logic Analyser -  This project was published in Electronics Australia in Oct/Nov 96.  it is a 32 Channel, 40Mhz, fully PC controlled TTL/CMOS logic analyzer with internal/external triggering and trigger delay.  internal triggering is fully maskable (High/Low/Don't Care) on all 32 channels.  The whole things fits on one single sided PCB with virtually no wiring!  __ 

40MHz Frequency Counter Module -  This circuit is ideal for adding a low cost frequency display to a function generator or other design.  I doubt if it is possible to get a cheaper design using off the shelf components! .  in fact, I challenge anyone to make a cheaper design using garden variety components! .  The upper frequency limit is dependent upon the upper limit of the 74HC390 chips which is roughly 40MHz.  __ 

4-20-mA loop needs no external power source -  09/13/01 EDN Design Ideas:  The simple circuit in Figure 1 uses a low-current-drain MAX4073H amplifier to sense the current flowing through a 4- to 20-mA loop.  The circuit senses the current through a 1Ω resistor with a fixed gain of 100 and uses no battery __ Circuit Design by Shyam Tiwari, Sensors Private Ltd, Gwalior, India

4-20mA Loop Transmitter -  Transmission of industry standard 4-20mA current loop signals to values and other actuators is a common requirement.  Resistive line losses and actuator impedances require current transmitters to be able to force a compliance voltage of a least 20V.  Because of this, 5V powered systems usually cannot meet current loop transmitter __ Linear Technology/Analog Devices App Note, Mar 16th 2011

45 MHz to 2050 MHz Spectrum Analyzer -  Schematic only __ Designed by va3iul

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if you want me to link to and/or post your original design.  Thanks.


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

 


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