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Tester or Measurement (Instrument) Circuits

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Last Updated: October 24, 2017 02:55 PM

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
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Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Simple Circuit Car Battery Charger psimages -  This very simple circuit uses a transformer , two diodes , a capacitor and an ammeter.  To charge a battery just connect+ and terminals of circuit to corresponding terminals of battery.  When battery is not charged, ammeter reading shows 1-3 amps__ 

Simple Circuit car battery Tester -  This circuit uses the popular and easy to find LM3914 IC .  This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source __ Designed by Jonathan Filippi

Simple Circuit car battery voltage Monitor -  A Very Simple circuit and some Variations.  Play with it.  All parts are cheap and should be easily obtained.   __ Designed by G.L. Chemelec

Simple Circuit Component & Continuity Tester -  This simple project can be used to test components, circuit board tracks, wires and connections.   __ Designed by John Hewes

Simple Circuit Continuity Tester Fits Into Shirt Pocket -  10-Jan-08 EDN Design Ideas:  A pocket-sized continuity tester responds quickly to shorts or opens and is protected against connection to a live circuit __ Circuit Design by Tom Wason, Phoenixville, PA

Simple Circuit Crystal Tester-F5JTZ -  Schematic only __ Designed by va3iul

Simple Circuit Data-Logging Weather Station, Pt.1 -  it's cheap and simple to build, operates completely unattended and will run for years on a set of AA batteries.__ SiliconChip

Simple Circuit Data-Logging Weather Station; Pt.2  -  Last month we introduced our new Rain and Temperature-Measuring Weather Station, with all the electronics.  This month we get into the nitty-gritty of building it - all the mechanical detail and then actual contstruction.__ SiliconChip

Simple Circuit Detects DC Ringing -  08/17/00 EDN Design Ideas:   Ring detection is a common task in telephony-related digital design.  The goal is to sense an ac ringing voltage applied to the telephone line by a central office or PBX (private branch exchange) and then pass an appropriate signal to the µC or µP __ Circuit Design by Jerzy Chrzaszcz, Warsaw Institute of Technology, Poland

Simple Circuit Detects voltage overrange -  10/10/96 EDN Design Ideas:  Sometimes, a visual indication of whether a sensed voltage is above or below its nominal value can be useful.  Most approaches to overvoltage or undervoltage sensing use two voltage comparators and a resistor divider to form a win __ Circuit Design by Mark Stitt, Burr-Brown, Tucson, AZ

Simple Circuit DIGITAL PANEL METER for Low-voltage measurements -  Here's one of those really handy little projects that will cost very little but make life a whole lot easier when you want to measure voltage and current at the same time.__ SiliconChip

Simple Circuit Diode Serves as a Sensor for a Thermal Probe -  02/16/12  EDN Design Ideas:  A two-transistor thermal probe can be used to diagnose circuit problems, such as hot components and thermal runaway.   __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, India

Simple Circuit disconnects load -  02/17/00  EDN Design Ideas:  Placing a load-disconnect circuit on the output of a bootstrapped step-up regulator allows the regulator to start with load currents much higher than would otherwise be possible (Figure 1).  During shutdown, the disconnect completely isolates the battery __ Circuit Design by Larry Suppan

Simple Circuit Disconnects Load From Battery -  03/14/96 EDN Design Ideas:  To prevent battery damage, the circuit in Figure 1 disconnects the load at a predetermined level of load voltage.  This load voltage, VTRiP, is closely proportional to the battery voltage.  R1 and R2 determine the level of VTRiP  that corresponds to voltage of 1.15V at pin 3 of IC 1.  A voltage of 1.15V at pin 3 of IC 1 causes the internal comparator to trip.  Thus, VTRiP=1.15 (R1+R2) /R1 __ Circuit Design by Michael Keagy, Maxim Integrated Products, Sunnyvale, CA

Simple Circuit Dual Constant-Current Load Tests Low-Current Power Supplies -  06/21/07  EDN Design Ideas:  You can use a simple 9V-battery-powered constant-current load to test small power supplies at various loads __ Circuit Design by John S Lo Giudice, STMicroelectronics, Schaumburg, IL

Simple Circuit Electronic Breaker -  This circuit uses the on-resistance of the MOSFET as the current sensor.  Reset it by removing the input power or the load.  The circuit draws no current unless tripped.   __ Designed by Andrew R. Morris

Simple Circuit Electronic S Meter -  This circuit is really a low-level voltage meter and could even be used for audio purposes. Pins 4, 6, 8 and 10 of IC 1 are connected together and are connected to the AGC line or the input to the last audio stage. Adjust R9 for the desired sensitivity. Resistors R5 through R9 provide voltage references for each of the OP Amps. R5 has the lowest reference voltage while R8 has the highest __ Designed by Radio Amateur Society of Norwich Mike Martell N1HFX

Simple Circuit Emulator Speeds Testing -  09/25/03 EDN Design Ideas:  Designing and testing embedded hardware can be frustrating if you have to rely on somebody else's perhaps-unready firmware to test your hardware.  Often, hardware is ready for testing before debugging and system firm-ware are available from software developers.  Microprocessor emulators are solutions but are often expensive, hard to use, and sometimes inappropriate for use by hardware developers,  __ Circuit Design by Navdhish Gupta, Chicago, IL

Simple Circuit ESD Gun Tests IC -  09/12/96 EDN Design Ideas:  You can use the simple ESD-test gun in Figure 1 to test the effects of ESD through sensitive IC s.  A piezo-electric type kitchen gas lighter (the so-called ESD gun]is an excellent fast-static-charge generator.  This gun can cause ESD through air and also through conducting and semiconducting materials __ Circuit Design by Shyam Sunder Tiwari, IGCAR, Kalpakkam, India

Simple Circuit Field Strength Meter -  This Field Strength Meter is simple and also quite sensitive.  it uses an ordinary digital voltmeter to measure RF signal strength up to a few hundred MHz.   __ Designed by Andy Collison

Simple Circuit fixture Determines leakage of capacitors & semiconductor switches -  06/07/07 EDN Design Ideas:  The low input-bias current of a voltage-follower op amp allows this simple fixture to measure the leakage current of capacitors and reverse-biased active devices __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Simple Circuit Fixture Statically Tests Programmable-Gain Amplifiers -  06/26/08  EDN Design Ideas:  Using a simple fixture having a common ground point, you can statically test digital gain-programmable amplifiers __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Simple Circuit forms multichannel temperature Monitor -  03/04/04 EDN Design Ideas:  You can use an ADT7461 single-channel temperature monitor, an ADG708 low-voltage, low-leakage CMOS 8-to-1 multiplexer, and three standard 2N3906 PNP transistors to measure the temperatures of three separate remote thermal zones (F __ Circuit Design by Susan Pratt, Analog Devices, Limerick, Ireland

Simple Circuit Frequency Counter -  This is the support page for the simple frequency counter project in Homebrew, RadCom October 2006.  The original design used a gate time of one second which gives a count resolution of 1Hz.  Maximum input frequency is about 50MHz.  A VHF/UHF prescaler for this counter is described in Homebrew, RadCom February 2008.  U2 is a PIC 16F628 (PIC 16F628-20 or PIC 16F628A).  The PIC  crystal frequency is 10.240MHz.  The firmware is easily modified so that a 10MHz crystal can be used instead.  Homebrew for March 2008 shows how this counter can be used with a GPS or Loran controlled gate. __ Designed by EI9GQ homebrew radio

Simple Circuit Frequency Meter -  10Hz - 200kHz in three ranges; Operates in conjunction with a Digital Multimeter __ Contact Flavio Dellepiane, fladello @ tin.it

Simple Circuit indicates a Low battery -  02/03/14 - EDN Design Ideas:  it may seem a bit counterintuitive to power on an LED when a battery is already low, but this Design idea does it with aplomb __ Circuit Design by James Wood

Simple Circuit Indicates Health of Lithium-Ion Batteries -  05/14/09  EDN Design Ideas:  A simple inexpensive circuit quickly indicates a battery pack's health __ Circuit Design by Fritz Weld, Friedberg, Germany

Simple Circuit Inductance Meter -  You might want to measure inductance of hand-wound toroidal coils or surplus canned coils.  A simple inductance meter made of cheap computer crystal oscillators is a useful tool for that purpose. __ Designed by MINOWA, Makoto  7N3WVM

Simple Circuit Lets You Characterize JFETs -  04/06/12  EDN Design Ideas:  Measure the pinch-off voltage VP and zero-bias drain current iDSS to select matched pairs of JFETs.   __ Circuit Design by John Fattaruso

Simple Circuit Lie Detector -  Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth.  it is not as sophisticated as the ones the professionals use, but it works.  it works by measuring skin resistance, which goes down when you lie __ Designed by Aaron Cake

Simple Circuit light sensor adapter for oscilloscope -  This circuit is a simple visible light or IR detector for testing any equipment which outputs light. The circuit can be also used for measuring ambient light levels.  This circuit is based on one photodiode which is used in photocell mode so that the photodiode generates a voltage and current signal when it get light.   __ Designed by Tomi Engdahl

Simple Circuit Lightning Detector -  Schematic + info + pictures __ Designed by Lennie Zink

Simple Circuit LM335 thermometer -  The circuit consists of two parts: The LM335 and its adjustment.  The output of the LM335 is 10 millivolts per degree C, with 25 degrees C corresponding to 2.982 VDC.  A reference circuit provides a zero reference voltage.  it is adjusted to (2.982 volts - (25 degrees x 10 millivolts/degree) = 2.732 volts.  To read the temperature of the LM335 directly in degrees C, connect the + lead from a high impedance DVMto the output pin and the - end of the DVM to the 2.732 volt pin.   __ Designed by Dick Cappels

Simple Circuit logic analyzer pushes microcontroller to its limit -  12/07/00  EDN Design Ideas:  A simple logic-analyzer design is compatible with all versions of Windows and pushes the PIC  18C252 chip to its speed limit to achieve a 1-MHz sampling rate (Figure 1).  The circuit can examine three channels of relatively low-speed logic signals that have infrequent, or sparse, transitions.  The analyzer can record only 510 transitions per run, but a run can last as long as several minutes, if necessary.  Applications include monitoring the i/O of an iBM keyboard or printer port, Ti-calculator intercommunication, and serial (RS-232) signals __ Circuit Design by Tom Lyons Fisher, Inexpensive Systems, Huntingdon, PA, and Michael Deskevich, Juniata College, Huntingdon, PA

Simple Circuit Logic Probe uses Bicolor LED -  03/13/98 EDN ideas - (FILE
has several circuits, scroll to this one) A project posed the challenge of replacing existing analog potentiometers (used to set brightness and contrast levels]in video monitors with digitally controlled potentiometers.  The different brands and models of monitors presented widely varying voltages across the potentiometers.  The design.    __ Circuit Design by Mark Shill, Burr-Brown Corp, Tucson, AZ

Simple Circuit Measures Diesel's Rotations Per Minute -  03/04/99 EDN Design Ideas:  You may find it useful to measure a diesel engine's rotations per minute to accurately adjust the idling or to compare the motor's speed under hot and cold conditions, for example.  Not all cars or trucks come with a tachometer.  The scheme in Figures 1 and 2 allows __ Circuit Design by David Magliocco, CDPI, Scientrier, France

Simple Circuit Measures Optocoupler's Response Time -  09/08/11  EDN Design Ideas:  Measure the response speed of optocouplers in order to select matching devices.  You can use the circuit in this Design idea to measure the attack and release times of photoresistor-type optocouplers (Figure 1).  Such devices often find use in audio compressors or volume-control circuits.  The design uses an oscillating Schmitt trigger with the optocoupler DUT (device under test) in the feedback loop.  The photoresistor and resistor R1 form a voltage divider that controls the input of the Schmitt trigger.   __ Circuit Design by Peter Demchenko, Vilnius, Lithuania

Simple Circuit metal Detector based on a PIC12F683 microcontroller -  The idea of this circuit is to hack PIC  oscillator circuit, by replacing the crystal by a coil : the frequency of the oscillator then depends on presence of metal near the coil, just like in a classic metal detector. __ Designed by Bruno Gavand

Simple Circuit metal Detector Electronic -  All the parts for the PC board, PC board, battery and winding wire $10.00  including pack and post. You will also need an AM radio, base-board to mount the parts and a wooden handle approx 1.5 metres long. __ Designed by Collin Mitchell

Simple Circuit method measures duty cycle -  EDN  Design ideas - 03/03/1997   Various methods exist to measure the duty cycle of a digital waveform.  For example, some simple PWM A/D converters give their output as a square wave whose mark/space ratio varies according to the analog input signal.  Some modern light and pressure sensors produce an output that is a duty-cycle-modulated digital signal.  You can also measure duty cycle with a µP by using two counters gated with the appropriate mark/space states of the input signal.  The problem with this approach is that today's tiny µCs, such as the 68HC05K1, include no general-purpose timers. __ Circuit Design by Jarkko Vuori, Helsinki University of Technology, Finland

Simple Circuit method tests cables -  10/17/02 EDN Design Ideas:  MOSFET serves as ultrafast plate driver - Engineers have long known how to test a cable for continuity by simply connecting all conductors in series and checking with an ohmmeter.  This method is sometimes impractical, however, because it cannot check for short circuits.  The method shown in Figure 1 solves the short-circuit problem.  Connecting __ Circuit Design by Jim Keith, Bell-Mark Technologies, Dover, PA

Simple Circuit MIDI Tester -  Sometimes when experimenting with different soundcards and MiDI interfaces it is useful to see if there is some data going in MiDI interface.  This can be easily tested with this adapter, which converts the midI signals to visible light pulses.  Just the circuit and plug it to the MiDI output of your computer.  When computer sends any midI data out, you see the LED flashing.  I found this tester very useful in testing homebuilt soundcard MiDI interface. __ Designed by Tomi Engdahl

Simple Circuit Moisture indicator -  No circuit description, schematic only__ CdS Electronic

Simple Circuit Monitors battery voltage -  11/21/96 EDN Design Ideas:  The circuit in Figure 1 monitors four NIC d rechargeable batteries and causes the LED to flash if the voltage of the batteries goes lower than 4V.  The circuit consumes only 8 mA of current under normal operating conditions.   IC 1 is an eight-pin IC that includes an op amp, a comparator, and a 1.2V zener diode.  The zener diode connects to the negative input of the comparator in the IC as a reference.  R6 and R7 divide the battery voltage __ Circuit Design by Yongping Xia, Philips Lighting Electronics Co, Torrance, CA

Simple Circuit Motion Detecting camera using PIR passive infrared -  A simple automatic motion-detection Digital Camera.   __ Designed by Collin Mitchell

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