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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. :
A Current Transformer used to Harvest Energy -  Energy harvesting is all the rage these days.  With some modern electronics, information from low power sensors can be sent to a distant data collection point using a low power RF transmitter.  To power these remote sensors, various energy sources can be . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2010

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:

A 10 Bit LED Digital Panel Meter -  With Auto Ranging Based on ATMEGA 8   ATMEGA8 __ Designed by Dick Cappels

A 10 Watt RMS Amplifier -  A Very Simple 12.5 Watt RMS Power Amplifier, into an 8 ohm load and with the op-amp driver.  This was the Maximum output before Clipping on the Oscilloscope, using an 8 Ohm Resistive load.   __ Designed by G.L. Chemelec

A 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

A 12/24V Intelligent Solar Power Battery Charger. -  Don't cook your batteries by connecting them directly to a solar panel.  This charger turns off the power when the battery is charged.__ SiliconChip

A 300 MHz  Prescaler & 30 MHz preamp for a 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

A Barometer That Measures Your Height -  31-Jul-09 -Design News:   Here's a weather instrument - the Dodecahedral Barometer - that can actually determine how tall you are by reading the barometric pressure between your head and your feet.  Mark Thoren notes that his gadget was inspired by the release of some new electronic products.  The first is a Serta model 270 __  Gadget Freak-Case #145

A Battery Powered Lap Top Computer Power Supply -  DN18 Design Notes __ Linear Technology/Analog Devices

A BFO Metal Detector -  Not the best, but Simple, and Now with a PCB.   __ Designed by G.L. Chemelec

A Car Coil Output Voltage Tester -  These circuits are designed to Test the High Voltage Output of a Car ignition Coil.   __ Designed by G.L. Chemelec

A Comparison of Leading Switch/Measure Solutions -  Application Note__ Aligent

A Crystal Heater construction project -  OK, here is the circuit I used - See image below.   The original National Semiconductor circuit had a 30 K resistor in series with a 400 F cap., both in parallel with the 100 K resistor on the input of the 1st LM324 section.   I found that combo to actually destabilize the operation of the controller for this particular application, so I removed them & changed the 2 F cap in series with the 10 megohm resistor to 5 F.__ Bobengler   NO6B

A Current Transformer used to Harvest Energy -  Energy harvesting is all the rage these days.  With some modern electronics, information from low power sensors can be sent to a distant data collection point using a low power RF transmitter.  To power these remote sensors, various energy sources can be . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2010

A Digital Thermometer/Thermostat -  it covers the range from -55 C to 1200C and has an over or under temperature alarm and switched outputs for thermostatic control.__ SiliconChip

A Digital Voltmeter for Your Car -  A PIC  microcontroller makes it a snack to build.__ SiliconChip

A Field Strength Indicator-Analog only -  The circuit is powerd by a single 1.5 volt AA cell.  The current drain is so small, about 60 microamps, I didn't bother with an on-off switch -I just slip a battery in for the day, and hope I remember to remove it when i'm done.  The supply voltage can be increased up to the breakdown voltage of the transistors to increase the sensitivity, but beware - the sensitivty to thermal drift will increase as well.   __ Designed by Dick Cappels

A Frequency Division Battery Detector  -  This simple circuit uses an ultrasonic sensor (part # 255-400SR16) from Mouser electronics.  it amplifies the signal and then converts the ultrasonic frequency by digital division down to a human frequency.  The resulting sound at the headphones is a "buzz" when a bat calls nearby __ Contact archilochus57 @ yahoo.com

A High Efficiency & High Power Chopper QRAS -  This paper is a record of the study on a high efficiency and high power chopper based on the new soft switching method QRAS (Quasi-resonant Regenerating Active Snubber) designed for a Fuel Cell Electric Vehicle (FCEV).  This power chopper is basically proposed for 25kHz soft switching.  To confirm the practicality and effectiveness of the converter, the fabrication of a prototype-model using iGBTs was completed __ Designed by Yukinori Tsuruta and Atsuo Kawamura

A Little More Serious Frequency Meter -  Maximum input frequency is specified to be 30 MHz in the multi-chip configuration, and in single-chip configuration, there are both 5 MHz and 10 Mhz versions operating with 10 and 20 MHz crystals, respectively.  All versions have 9 1/2 digit resolution.  I have used __ Designed by Dick Cappels

A Load Box for testing power supplies -  A common mistake made by students in beginning electronics laboratories is to test a power supply by connecting a resistance decade box or resistor substitution box across the output.  The smell of burning resistors quickly alerts everyone that someone has goofed.   __ Designed by Max Robinson

A Low Battery Cutoff -  Also acts as a Master On / Off Switch.  NOW, Also a New P-Mos Version.  Supplies Positive voltage to grounded devices.   __ Designed by G.L. Chemelec

A Low Cost Thermal Peak Detection NiCd Charger -  The electric model aircraft and car industries have produced a bewildering array of field chargers for NIC d motor battery packs.  These range from simple 6 or 7 cell chargers consisting of a resistor and mechanical timer, to more complex chargers with peak detection, cycling, and the ability to handle 36 cell packs __ Designed by Stefan Vorketter

A Low-Capacitance Adaptor for DMMs -  This neat little adaptor allows a standard digital multimeter to measure low values of capacitance - from less than one picofarad to over 10nF.  it will allow you to measure tiny capacitors or stray capacitances in switches, connectors and wiring.__ SiliconChip

A Low-Cost 50MHz Frequency Meter -  it features an LCD readout, auto-ranging and two resolution modes.  And it can be run from a plugpack or battery operated.__ SiliconChip

A Low-Cost PC-to-I2C Interface for Debugging -  Tracking down problems in circuits which are programmed via an i2C bus can be tricky and time-consuming, unless you take advantage of a debugging program running on a PC.  Here's a low-cost, easy-to-build printer port to i2C interface designed to work with the Philips/NXP debugging program URD312.exe.__ SiliconChip

A Low-power Battery-less Wireless Temperature and Humidity Sensor with Passive Low Frequency RFID -  This design, featuring the ultra-low-power MSP430 MCU paired with a TMS37157 Passive Low Frequency RFID device can enable a ultra-low power wireless temperature & humidity sensor (SHT21). With RFID, applications can benefit from hermetically sealed enclosures by leveraging RFID to provide power and data transmission wirelessly through an enclosure. This design provides complete hardware, software & PC-side software to get you up and running.__ Texas Instruments

A Milliohm Adaptor for Digital Multimeters -  Do you occasionally need to measure very low resistances accurately but don't have access to an expensive benchtop Milliohm Meter or DMM? This low-cost adaptor will let you use almost any DMM to make accurate low-resistance measurements.__ SiliconChip

A Monolithic IC for 100MHz RMS-DC Conversion -  Linear Technology AN22 __ Designed by Jim Williams - Sep 1st, 1987

A mV Source for Thermocouple simulation -  I realized early that for prototyping and troubleshooting, I would require a millivolt source which can simulate a type K TC.  For now, this circuit is what I devised.  When the ECU is complete, I will do final calibration with a lab-grade TC simulator, and develop software interpolation of the non-linear curve.  But to simply create the Op-amp interface to amplify the signal, this little circuit seems to work quite well.  it is mounted on a 2" square PC board with a 9V battery.  I used a 10-turn 1K pot (expensive).  A normal pot will work fine.  Vary the 120K resistance to increase or decrease the mV signal range.  in this configuration, it will output a fairly stable 0 to 40 mV.  __ 

A Noise Generator per IEC 268-1, IEC 268-5 & IEC 268-7 -  This is a noise generator that provides Broadband Audio White Noise, Pink Noise, andClipped Pink Noise for the testing of loudspeakers and headphones in accordance with iEC 268-5, and iEC 268-7, respectively, as well as many other uses.   __ Designed by Dick Cappels

A Nominal 10 Watt Power Amplifier -  A Very Simple 12.5 Watt RMS Power Amplifier, into an 8 ohm load and with the op-amp driver.  This was the Maximum output before Clipping on the Oscilloscope, using an 8 Ohm Resistive load.   __ Designed by G.L. Chemelec

A PC Games Port Tester -  So your joystick dosen't work? is it the games port, a software problem or the joystick itself? This simple device will tell you if the games port is OK.__ SiliconChip

A Photo Tour of a Bird Wattmeter Element -  Ever wonder what's inside one of those elements?  __ Designed by Robert W. Meister WA1MIK

A Photocell Amplifier for Comparative Light Measurements (analog only) -  This is a low frequency amplifier with an adjustable transimpedance that is intended to be used to take relative measurements of a wide range of photo currents.   __ Designed by Dick Cappels

A PID Temperature Controller -  What's a PiD controller? PiD stands for "proportional integral differential" and relates to a process which seeks to continuously correct the error between a measured variable and a desired setting by calculating an appropriate correction process.  in practice, it can largely avoid the large overshoots and undershoots that occur in simple temerature control systems.__ SiliconChip

A Poor Ham's Deviation Meter -  A theory and practice article on measuring deviation of FM transmitters,  __ Designed by Robert W. Meister WA1MIK

A Poor Man's Q Meter -  Simple circuit mates with an RF signal generator and multimeter for quick-and-easy "Q" and inductance measurements.__ SiliconChip

A Portable Lightning Detector -  This little device could save your life...__ SiliconChip

A Power Monitor for AC Lines of 110 to 240 VAC -  May be useful to some persons.   __ Designed by G.L. Chemelec

A Precision Portable Voltage Reference -  it has been said that a man with one watch knows what time it is, but a man with two watches is never sure.    The same can be said for a person who has more than one voltmeter.    in my situation, I have several voltmeters in each of two different locations a third of the way around the world apart.  The best solution would be to send the meters to  NiST traceable calibration labs,  __ Designed by Dick Cappels

A precision T/C Amplifier with cold junction compensation for the BS2 -  A thermocouple signal is quite small, and the long thermocouple leads often induce quite a bit of noise into the system.  This new circuit is far more accurate, stable, and less immune to noise.  it makes use of a Linear Technologies LT1025 chip to provide CJC (Cold Junction Compensation) , an LTC1098 8-bit 2-channel Analogue to Digital Converter, and an LTC1050 chopper amp.  The feedback resistors are designed to deliver 5V (full scale signal) to the ADC with a 1000 degree C.  Type K signal.  The 1050 is a great amplifier, delivering "rail to rail" output which makes powering the circuit simple.  __ 

A Precision Wideband Current Probe for LCD Backlight Measurement -  DN101 Design Notes__ Linear Technology/Analog Devices

A Pretty Good LC Meter Based on an AVR ATtiny2313, AT90S2315 -  Calculates and displays L and C from oscillation frequency using reference components.  No relays, no range switching, a minimum of controls.  And it is pretty accurate too!  __ Designed by Dick Cappels

A primer on binary-arithmetic rounding -  01/21/99 EDN Design Ideas:  (Scroll to find this one) As digital communications and data compression/decompression proliferate, signal-processing functions grow in importance.  Whether youre dealing with hard-wired logic or programmable engines, an understanding of binary-arithmetic rounding is important in getting correct and consistent results.  Before we discuss rounding, consider a binary number (Figure 1)    Page includes several designs.   __ Circuit Design by Tom Balph, Motorola SPS, Tempe, AZ

A Programmable Continuity Tester -  Our go/no-go continuity tester giving you the ability to set minimum continuity.__ SiliconChip

A Programmable PIC-Powered Timer -  This PIC -based timer can be set for any period from one second up to 680 days and even (theoretically) up to nearly 60 years.__ SiliconChip

A Programmable-Continuity-Tester -  Easy-to-build unit lets you set the continuity "pass" threshold to anywhere between 1Ω and 100Ω.  it makes an ideal go/no-go tester.__ SiliconChip

A purpose-built MotrAC Metering set -  I needed to tune a Motrac-based Compa-station but had no official metering set.  I had a meter; I bought everything else.  You can modify the design to suit your needs.   __ Designed by Robert W. Meister WA1MIK

A Remote Telltale for Garage Doors -  if you have a perfect memory you won't need this.  But the rest of us could find it very handy!  it lets you know if you've left the garage door open without stumbling out in the dark or the pouring rain...__ SiliconChip

A Robust, Low Power, Battery Monitoring Front End  -  To program the board with the PC, install the evaluation software.  To do this, load the evaluation software by placing the CN-0253 evaluation software CD in the CD drive of the PC.  Using My Computer, locate the drive that contains the evaluation software CD and open the Readme file and follow the instructions for installing and using the evaluation software.  , Functional Block Diagram of Test Setup Figure 4 shows the test setup functional block diagram__ Analog Devices from the Lab

A Simple Circuit & inexpensive laser power meter -  The construction of a simple and inexpensive laser power meter is described.  The laser power is monitored using a calorimeter sensor which is based on the use of commercial platinum resistors.  in this design, the use of volume absorbing glass enables the meter to withstand peak power densities in the region of 100 MW cm-' and average powers in excess of 10 W at 1.06 pm __ Designed by A. I. Ferguson

A Simple Circuit Attenuator & Preamp for DC Measurements  (Analog Only) -  A battery powered attenuator and preamp to extend the range of a voltage recorder.  Gains cover 40db, 20db, and 0 db and can run for thousands of hours on a single coin cell.   __ Designed by Dick Cappels

A Simple Circuit BFO Metal Detector -  A Very Simple "Beat Frequency Oscillator" type of Metal Detector.  These are about the Simplest of all Metal Detector types, But still quite useful for many Detecting applications.  And although this one is particularly simple, I find it works very well.  For use outside on the ground the coil "MUST have a Faraday Shield", or it will not be of any use because of Ground Effects.  __ 

A Simple Circuit Manual Curve Tracer (analog only)   -  Measure current vs voltage or voltage vs current over limited range with good accuracy __ Designed by Dick Cappels

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


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