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Tester or Measurement (Instrument) Circuits

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

Turn D-Flip/Flop into a One Shot 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 . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

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Translate a laW to m law -  05/07/98 EDN Design Ideas:  (NOTE: contains several ideas, scroll down) Two common methods exist to compand voice for transmission through a PCM channel.  in Europe, A law involves converting a 12-bit input signal to an 8-bit encoded output.  in the US, m law involves encoding 13 bits to 8 bits.  You can use a translator to convert from A law to m law (Figure 1).  The converter is asynchronous and requires only an 8-bit A law input to provide an 8-bit m law output. __ Circuit Design by Rolando Herrero, Instituto Tecnológico de Buenos Aires, Argentina

Transmission Line Terminations -  (spice design)  __ Designed by Rick 

Transmission Line Tests 1-Kw Device using Only 100W -  20-Feb-03 EDN Design Ideas:  A 13.56-MHz, iSM (industrial, scientific, and medical]-band RF-measurement device had the test requirement of a 50-hour, 1-kW burn-in.  The device under test needed to be simultaneously stressed at an RF potential and RF current equivalent to 1 kW, but the only spare RF source at hand was a 100W RF generator __ Circuit Design by David Cuthbert, Meridian, ID

Transmission Lines Simulate Digital Filters In Pspice -  04/17/08  EDN Design Ideas:  You can simulate digital filters in PSpice by using transmission lines as delay elements __ Circuit Design by David Báez-López, Department of Electrical and Computer Engineering, Ryerson University, Toronto, ON, Canada

Transmitter Accurately Transfers Voltage Input -  15-May-03 EDN Design Ideas:  When you connect remote sensors to a central process controller, a simple, robust, and commonly used interface is the 4- to 20-mA loop.  The advantages of this current loop include the simplicity of just two twisted wires that share both power and signal, the loop's high noise immunity in harsh environments, and the de facto loop standard within the process-control industry __ Circuit Design by Clayton Grantham, National Semiconductor, Tucson, AZ

Transmitter senses triple relative-humidity figures -  09/26/02 EDN Design Ideas:  The circuit in Figure 1 is a triple, relative-humidity sensor and radio transmitter.  Sensors 1 and 2 form two gated oscillators with natural frequencies of 10 and 5 kHz, respectively, at relative humidity of 50%.  The gated oscillators use variable resistances R2 and R3, respectively.  Together, these two oscillators generate FSK-modulated outputs at output of IC 1B, Pin 6 __ Circuit Design by Shyam Tiwari, Sensors Technology Ltd, Gwalior, India

TRIAC Tester Allows for Manual or Automatic Operation -  20-Aug-09 EDN Design Ideas:  Build a simple TRIAC tester with a switch or an automated tester with a microcontroller __ Circuit Design by Abel Raynus, Armatron International, Malden, MA

Triangle / Square wave Generator -  Here is a simple triangle/squarewave generator using a common 1458 dual op-amp that can be used from very low frequencies to about 10 Khz.  The time interval for one half cycle is about R*C and the outputs will supply about 10 milliamps of current.  Triangle amplitude can be altered by adjusting the 47K resistor, and waveform offset can be removed by adding a capacitor in series with the output. __ Contact IQ Technologies

Triangle Wave Audio Astable -  a useful replacement for a sine wave generator, has ac/dc output and square and triangle outputs __ Contact P. Townshend - EduTek Ltd

Tritium - Type 3 (charge rate controlled) Solar Engines

True RMS Watt Meter -  This circuit will give you a good, Accurate Watt Meter that can measure various power levels.
in the Origional Article the Shunt was a .001 Ohm Copper Shunt giving a 1000 Watt Scale.   However, because Most Circuit Breakers in homes are 15 Amps, I made my unit to have a range of Zero to 1500 Watts. __ Designed by G.L. Chemelec

TRUE RMS-TO-DC Adapter for DVM -  The main differences between one of the application circuits in the AD737 data sheet are the addition of a MCP1702 micropower 3.3  volt regulator to split the power supply and two 11 volt zener diodes to prevent the voltage across the chip to become high enough to damage the chip in case the input is connected to an excessive voltage while in the 200 mv full scale setting.  __ 

TTL pulse counter/logic probe -  When building and troubleshooting TTL circuits, I'veused this thing more than just about any other tool.  I needed something that could detect whether a pulse was occurring on a signal line, and just as importantly, whether more than one pulse occurred or not. __ Designed by Frank Crivelli & Peter Crowcroft

TTL Pulse Reading Logic Probe -  This circuit uses LEDs to display logic states for high, low, rising pulse, and falling pulse, it is generally useful for debugging logic circuitry.   __ Designed by G. Forrest Cook

TTL/CMOS Logic Probe1 with Pulse -  One of the most frustrating problems with experimenting is not be able to check the logic state of TTL or CMOS ic's without the use of a triggered oscilloscope. The schematic diagram above shows a simple and inexpensive way of building a 'Logic Probe' yourself. it will provide you with three visible indicators; "Logic 1" (+, red led) , "Logic 0" (-, green led) , and "Pulse" (yellow led)  __ Designed by Tony van Roon  VA3AVR

TTL/CMOS Logic Probe2 -  This circuit uses the four 2 input NOR gates contained within the 4001 CMOS IC , and is primarily intended for testing CMOS circuits.  The probe derives its power from the supply of the circuit being tested.  The first gate, N1, has its inputs tied together so that it operates as an inverter, and it is biased by R1 so that roughly half the supply potential appears at its output __ Designed by Tony van Roon  VA3AVR

TTL/CMOS Logic Probe3 -  A logic tester with an audible indicator can be handy when troubleshooting or testing a crowded circuit board.  it allows you to keep your eyes on the circuit, rather than on a LED on the tester.  The project described in this article is just such a tester.  it provides an audible indication of the logic level of the signal presented to its input __ Designed by Tony van Roon  VA3AVR

Turn D-Flip/Flop into a One Shot 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 . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

TV Oscilloscope Adaptor -  This is an adapter attached to a TV set.  This machine changes a TV to a Oscilloscope.  See the photo! This photo indicates a sine wave 50mV 120Hz.  See the circuit!  Free oscillater makes an 15kHz pulse signal (A).  This signal is amplified by an buffer AMP.  On the other hand , an amplifier makes 300 times of input signal.  And it is shifted to 6V center.  A comparater.  __ 

TV Oscilloscope Adaptor #2 -  Low frequency TV Oscilloscope __ Designed by Sunamura Kazuhiro

TV Tuner Spectrum Analyzer-WA2PZO -  Schematic only __ Designed by va3iul

Two ADC channels double sensor precision -  03/18/99 EDN Design Ideas:  (PDF contains multiple circuits, scroll to find this circuit) The accuracy of the onchip ADCs of numerous small and inexpensive 8-bit mPs is well-suited for many applications.  However, some  situations benefit from.   PDF contains multiple circuits, scroll to find this circuit __ Circuit Design by Luke J Barker, Reinke Manufacturing Co Inc, Deshler, NE

Two chips LED Frequency Counter-PA2OHH -  Schematic only __ Designed by va3iul

Two diodes change Demagnetization-signal polarity -  04/12/01 EDN Design Ideas:  Power-supply designers usually like flyback converters to operate in DCM (discontinuous-conduction mode) rather than in CCM (continuous-conduction mode).  in DCM, the flyback converter is a first-order system at low frequencies, which eases the feedback-loop compensation.  You can use a low-cost secondary rectifier, thanks to soft blocking conditions __ Circuit Design by Christophe Basso, On Semiconductor, Toulouse, Cedex, France

Two Sensors Measure Three Line Current -  09/01/95 EDN Design Ideas:  An old technique updated for modern requirements allows you to measure all three line currents in a three-phase system.  You perform this measurement using two current transformers (CTs) and three ammeters.  The original technique appeared in Alternating-Current Machines by George Mueller (McGraw-Hill, 1952).  The method works equally well with modern current sensors.  Figs 1 and 2 illustrate the technique.    __ Circuit Design by Henno Normet, Tavares, FL

Two Tests for Crystal -  Two simple test circuits to check operation of quartz crystals __ Designed by Andy Collison

Two Tone Audio Oscillator -  Circuit Only __ Contact Peter Parker VK3YE

Two-component metal Detector -  The circuit shown must represent the limits of simplicity for a metal detector.  it uses a single 4093 quad Schmitt NAND IC and a search coil -- and of course a switch and batteries.  A lead from IC 1d pin 11 needs to be attached to a MW radio aerial, or should be wrapped around the radio.  if the radio has a BFO switch, switch this ON.  Since an inductor resists rapid changes in voltage (called reactance) , any change in the logic level at IC 1c pin 10 is delayed during transfer back to input pins 1 and 2.  This is further delayed through propagation delays within the 4093 IC .  This sets up a __ Designed by © Rev. Thomas Scarborough

Two-component metal Detector using a 4093 -  The circuit shown must represent the limits of simplicity for a metal detector.  it uses a single 4093 quad Schmitt NAND IC and a search coil — and of course a switch and batteries.  A lead from IC 1d pin 11 needs to be attached to a MW radio aerial, or should be wrapped around the radio.  if the radio has a BFO switch, switch this ON. __ Designed by Rev. Thomas Scarborough

Two-Terminal Temperature-to-Current Thermometer Suitable for Use at the End of Long Wire Runs -  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, Oct 26th 2010

TXTVb-70cm ATV Test Generator -  A low cost ($30) , low power 70cm ATV generator can have many uses in the shack and for demo’s.  The TXTVb board will put out 1 to 10 milliwatts with DC inputs of 8 to 14 Vdc @ 40 mA.  For portable, it can run on a 9V alkaline battery for over 8 hours __ Designed by Tom (W6ORG) & Mary Ann (WB6YSS)

Type K Thermocouple Signal Conditioner with ±190V Protection from Accidental Contact & Cold Junction Compensation -  Thermocouple wires are intended to be electrically floating in order to detect temperature by producing the Seebeck voltage created by two dissimilar metals.  This small voltage is amplified to an easily measurable level by an amplifier.  To protect the input terminals of the amplifier in the event that the thermocouple is shorted __ Linear Technology/Analog Devices App Notes, Mar 16th 2010

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