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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. :

On/Off Flip/Flop Circuit with Automatic Timeout -  This circuit is ideal when a device needs to be turned on and off with a single pushbutton switch, but also needs to turn itself off after some period of time.  With the components shown, the output will stay on for only about 20 seconds. . . Circuit by Dave Johnson P.E.-May, 2012

One Amp Current Injector -  I designed and built this thing many years ago.  I published the hobby circuit in the now defunct Radio Elecronics magazine back in 1992.  The electronic circuit injects a precise 1 amp of current into any unknown resistor, up to about two ohms.  Two alkaline . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

 

One NiMH
Cell powers White LED
-  There are a lot of white LED driver circuits floating around.  A popular circuit called the “Joule Thief” can drive one white LED from a single 1.2v or 1.5v battery cell.  Most of these circuits use one or two transistors to form a voltage boost circuit . . . Hobby Circuit designed by David A. Johnson P.E.-September, 2009

One Shot (D-Flip/Flop) Circuit -  Yes you can use cheap D flip/flop logic circuits as nice one-shot pulse generators.  This schematic shows how the popular CD4013 and the CD74HC74 can be used to generate pulses ranging from nanoseconds to seconds. . . Circuit by David A. Johnson P.E.-June, 2000

Oneshot & Latch Pushbutton -  This circuit uses a single IC to convert a noisy pushbutton switch signal into a clean pulse or a sustained push on-push off signal.  it can operate from 3v to 18v . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

Optical RFID Test Circuit -  I designed this test the concept of using light techniques to send identification data instead of RF.. . . Circuit by Dave 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:

Octopus Curve Tracer -  This project involves the construction of a low-cost curve tracer that is suitable for testing a wide variety of electronic components both in-circuit and out of circuit. it is easy to construct and extremely useful for finding defective parts, especially semiconductors, in electronic devices. __ Designed by G. Forrest Cook

Off Line Telephone Tester -  Here is a circuit of an off-line Telephone tester which does not require any Telephone line for testing a Telephone instrument.  The circuit is so simple that it can be easily assembled even by a novice having very little knowledge of electronics.  __ 

Office Monitoring System -  This system can be used in offices or hotels to call an attendant from seven different locations.  The circuit provides audio indication of the calling location to the attendant on a...__ Electronics Projects for You

On/Off Flip/Flop Circuit with Automatic Timeout -  This circuit is ideal when a device needs to be turned on and off with a single pushbutton switch, but also needs to turn itself off after some period of time.  With the components shown, the output will stay on for only about 20 seconds. . . Circuit by Dave Johnson P.E.-May, 2012

One Amp Current Injector -  I designed and built this thing many years ago.  I published the hobby circuit in the now defunct Radio Elecronics magazine back in 1992.  The electronic circuit injects a precise 1 amp of current into any unknown resistor, up to about two ohms.  Two alkaline . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

One Amplifier has two gain figures -  09/19/02 EDN Design Ideas:  The single-supply circuit in Figure 1 is an inverting amplifier with two outputs—one for positive output voltages, VOUT (POS], and the other for negative output voltages, VOUT (NEG].  Steering diodes D1 and D2 split the amplifier, IC 1, output into the two output polarities relative to the 2 __ Circuit Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CA

One 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

One 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

One 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

One IC Forms Precision Triangular-Wave Generator -  04/08/10 EDN Design Ideas:  Generate a triangular wave for testing other circuits.   __ Circuit Design by Akshay Bhat, Maxim Integrated Products Inc, Sunnyvale, CA

One NiMH
Cell powers White LED
-  There are a lot of white LED driver circuits floating around.  A popular circuit called the “Joule Thief” can drive one white LED from a single 1.2v or 1.5v battery cell.  Most of these circuits use one or two transistors to form a voltage boost circuit . . . Hobby Circuit designed by David A. Johnson P.E.-September, 2009

One Shot (D-Flip/Flop) Circuit -  Yes you can use cheap D flip/flop logic circuits as nice one-shot pulse generators.  This schematic shows how the popular CD4013 and the CD74HC74 can be used to generate pulses ranging from nanoseconds to seconds. . . Circuit by David A. Johnson P.E.-June, 2000

One 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

One Wire Barometer -  By using a dual voltage supply, instrument precision and/or instrument range can be improved without adding significantly to the parts count.   __ Designed by A.G. Miller

One 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

Oneshot & Latch Pushbutton -  This circuit uses a single IC to convert a noisy pushbutton switch signal into a clean pulse or a sustained push on-push off signal.  it can operate from 3v to 18v . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

One-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

On-Off Temperature Control -  This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. in fact when forward biased, the forward voltage drop accross a diode has a temperature dependance, in particular has a negative linear (ish) slope __ Contact Jonathan Filippi

Op Amp Comparator & Reference IC provides miscropower Monitoring capability -  Design Notes 190__ Linear Technology/Analog Devices

Op Amp increases potentiometer's resolution -  06/05/00 EDN Design Ideas:  A key parameter of digitally controlled potentiometers (DCPs] is the number of taps (n] programmable positions of the wiper.  This parameter establishes the resolution in  programmable-voltage and -current applications.  A number of circuitPDF has many circuits, please scroll to find this one __ Circuit Design by Chuck Wojslaw, Xicor Inc, Milpitas, CA, and P Gareth Lloyd, Elab Ltd, Stoke-on-Trent, UK

Opamp Design & Test Board -  Quickly assemble an OpAmp circuit for testing.    Very easy and intuitive to use __ Designed by Rod Elliott  ESP

Op-Amp Rectifier Signals Input State -  07/21/94 EDN Design Ideas:  The op-amp rectifier in Fig 1 operates from a single supply and provide as a logic output and an LED that indicate the state of the input voltage.  The input-state indications are handy for calibration.  Because the circuit operates from a single supply, the 2.5V reference determines the level around which the circuit rectifies input waveforms __ Circuit Design by Lee E Scaggs, High Country TEK, Nevada City, CA

OpenEEG open hardware EEG project -  Medical and health related electronic circuit diagrams / circuit schematics__ 

Optical Heart Rate Monitor -  Medical and health related electronic circuit diagrams / circuit schematics__ 

Optical Heart Rate Monitor Reference Design with BLE Connectivity -  This reference design is for a complete Optical Heart Rate Monitor wrist watch (no chest strap!) end equipment featuring TI signal chain, power, and connectivity components. With Ti’s AFE4400 AFE, you can accelerate and simplify your wrist based HRM design while still ensuring measurement performance needed for serious Fitness designs. This reference design also includes a full BLE connectivity design for easy interface to BLE enabled smartphones, tablets, etc.__ Texas Instruments

Optical RFID Test Circuit -  I designed this test the concept of using light techniques to send identification data instead of RF.. . . Circuit by Dave Johnson P.E.-February, 2002

Optical Smoke Detector -  This optical smoke detector uses a low-cost, readily-available, slotted, through-scan, infrared photo-switch.  When smoke is detected, the relay energises to activate the audio/visual warning alarm.  Fig.1 shows the circuit of the...__ Electronics Projects for You

Optical tachometer provides bidirectional info -  05/21/98 Design ideas - (Multiple circuits listed, scroll to find this one) Optical tachometers have many advantages in precision servo applications.  Compared with dc-generator types, optical tachs are relatively inexpensive and, because they lack wear-prone commutator brushes, they're long-lived.  Frequency-to-voltage conversion circuits provide a convenient means to integrate the output of optical tachs into analog, unidirectional motion-control loops.  However, for bidirectional servos, where you need a bipolar angular-velocity readout, you need a more unconventional solution, such as the circuit in Figure 1.    __ Circuit Design by Stephen Woodward, University of North Carolina, Chapel Hill

Optically Isolated Overcurrent Detector Works From AC Mains -  10/06/11  EDN Design Ideas:  The circuit uses two opto-transistors you arrange for bipolar sensing.  The circuit in this Design idea detects short-circuit faults or excess-current conditions in line-operated equipment, such as a UPS (uninterruptible power supply) , across an isolation boundary.  if the load current rises higher than a predetermined level, the circuit generates a 5V pulse to immediately shut down the power inverter.  This compact circuit provide as a reliable means for protecting power semiconductors and batteries against overcurrent conditions.  it features an isolated output and a fast response.  The ac mains self-power the sensing network.   __ Circuit Design by José M Espí, Jaime Castelló, Rafael García-Gil, and Marcos Arasa, University of Valencia, Valencia, Spain

Optimize linear-sensor resolution -  03/07/02 EDN Design Ideas:  A wide variety of sensors and transducers of physical phenomena work via the mechanism of variable resistance.  These devices sense temperature, light, pressure, humidity, conductivity, and force, for example.  Such sensors measure the physical parameter of interest by reading out the inherent parameter-sensitive resistance or conductance __ Circuit Design by Steve Woodward, University of North Carolina, Chapel Hill, NC

Optimizing Bluetooth Device Battery Drain Measurements in Manufacturing -  Application Note__ Aligent

Optocoupler extends high-side Current-sensorto 1 kV -  03/01/01 EDN Design Ideas:  The task of sensing dc current at high voltage is often problematic.  Most high-side current-sensing ICs  available off the shelf are good only to 30 or 40V.  Combining an optocoupler with such an IC yields a sensing circuit in which the only limitation of the high-side voltage is the optocoupler's standoff voltage (Figure 1).   __ Circuit Design by Roger Griswold

Optocoupler simplifies power-line Monitoring -  10-Jan-02 EDN Design Ideas:  The use of a linear optocoupler and a capacitor-based power supply yields a simple, yet precise power-line-monitoring system.  The circuit in Figure 1 converts the 110V-ac power-line voltage to an ac output voltage centered at 2.5V, covering 0 to 5V.  The circuit isolates the output signal from the power line __ Circuit Design by Alfredo del Rio and Ana Cao y Paz, University of Vigo, Spain

Oscillator/Reference Oven Temperature Regulation -  The LTC2990 is used to monitor system temperatures, voltages and currents.  Through the i2C serial interface, the device can be configured to measure many combinations of internal temperature, remote temperature, remote voltage, remote current and internal VCC.  The internal 10ppm/°C reference minimizes the number of supporting __ Linear Technology/Analog Devices App Note, Mar 16th 2011

Oscillators Convert Temperature to Time -  03/30/95 EDN Design Ideas:  Fig 1's simple arrangement of active-R oscillators accurately converts temperature into time.  Most designers use these types of oscillators for low-grade oscillators that don't have stringent waveshape and frequency-stability requirements.  However, the three-phase symmetrical active-R oscillator actually can generate an excellent triangular waveform.  in this case, the oscillators become relaxation generators in which the input stage's constant bias current periodically charges and discharges the op amp's compensation capacitor. __ Circuit Design by Dan Stiurca, Gh Asachi Technical University, Iasi, Romania

Oscilloscope helps obtain Bode plots in non-50Ω environments -  03/29/07  EDN Design Ideas:  Vertical amplifier isolates high-Z circuit from low-Z network-analyzer input __ Circuit Design by Antonio Eguizabal, Freescale Semiconductor Inc, Tempe, AZ

Oscilloscope Testing Module -  (Huntron circuit) that shows Lissajous patterns__ Pericom Semiconductor

Oscilloscope Trigger / Triggering Tutorial -  The oscilloscope trigger facility is one of the key functions within the oscilloscope.   Triggering enables the scope, whether digital or analogue, to display a steady image on the screen that can be viewed by the user / engineer investigating a particular circuit.   Without a trigger, or other form of synchronisation, it would not be possible to display a steady signal on the screen. __ Designed by Ian Poole

Overcurrent & Undervoltage Battery Fault Protection -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Overcurrent Battery Fault Protection -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  in addition, the current sense amplifier __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Overflow Water-Tank Indicator -  Water is a vital but scarce natural resource.  To prevent water wastage, this water-tank overflow indicator comes in handy.  it gives audio as well visual alarm whenever the water tank overflows.Fig....__ Electronics Projects for You

Over-Heating Indicator for Water Pipe -  The hot water pipe from the water geyser of your bathroom may burst if it gets overheated and is left unattended.  This circuit monitors the temperature of the water pipe.  if...__ Electronics Projects for You

Overload & Reverse Currentry Protects Battery & Load -  03/01/96 EDN Design Ideas:  Battery-operated equipment is prone to the consequences of backward-installed batteries, accidental short circuits, and other careless use.  The effects of a reversed battery are critical.  Unfortunately, it's difficult to guard against a reversed battery.  To make __ Circuit Design by Dana Davis, Maxim Integrated Products

Over-Temperature Alarm -  This circuit can be used as a warning device which triggers an alarm whenever the temperature exceeds a preset level.  it can also be used as a door-alert or general warning...__ Electronics Projects for You

Overvoltage Regulator with 250V Surge Protection -  The LT4363 surge stopper protects loads from high voltage transients.  it regulates the output during an overvoltage event, such as load dump in vehicles, by controlling the gate of an external N-channel MOSFET.  The output is limited to a safe value allowing the loads to continue functioning.  The LT4363 also monitors the voltage__ Linear Technology/Analog Devices App Note, Jan 16th 2012

Overvoltage Regulator with Low Battery Detection & Output Keep Alive During Shutdown -  The LT4356 surge stopper protects loads from high voltage transients.  it regulates the output during an overvoltage event, such as load dump in automobiles, by controlling the gate of an external N-channel MOSFET.  The output is limited to a safe value thereby allowing the loads to continue functioning.  The LT4356 also monitors__ Linear Technology/Analog Devices App Note, Apr 26th 2010

Owens Bridge Inductance Measurement Device -  The circuit is a very simple RCRCRC filtered supply and a current source.  The filtered supply provides 174 bolts at no load, and drops to 106 volts at 400mA.  Ripple must be relatively low.  in this supply, ripple is about 2 mV at 400mA load, so it is sufficiently filtered.  Available voltage ranges from 154 volts at__ Steve?

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Test Equipment:  #'s - A        B - D        E - G
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