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Voltage Detectors / Sensors / Monitors

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Detect & Disconnect Overvoltage -  04/25/96 EDN Design Ideas:  The circuit in Fig.1 protects circuits and systems with power supplies that may exceed safe limits.  One example is small consumer products that use external ac adapters; it's easy to mistakenly plug in the wrong adapter.  Another example is a portable system that uses a rechargeable battery pack.  if the battery pack is absent or fails to open during recharging, a high-compliance charger can deliver excessive voltages to the system __ Circuit Design by Kerry Lacanette, National Semiconductor Corp, Santa Clara, CA

Detect 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 C or P __ Circuit Design by Jerzy Chrzaszcz, Warsaw Institute of Technology, Poland

Detect First Event -  05/03/01  EDN Design Ideas:  The circuit in Figure 1 is a "first-event" indicator, like a game show's "who's first to answer" detector.  it indicates which of the two momentary switches, S 1 or S 2 , closes first by latching the corresponding channel, IC A or IC B , to a high state.  A __ Circuit Design by Kelly Flaherty, National Semiconductor, San Mateo, CA

Detect Reset Source -  04/27/00 EDN Design Ideas:  Embedded single-board computers do not rely only on power-on resets; they often use multiple sources to reset CPUs to prevent CPUs from being locked into endless loops.  However, in most cases, CPUs start from the starting points of memories to fetch their first code, because they have no way of knowing what generated the reset.  The circuit in Figure 1 allows a CPU to know the source of a reset.   __ Circuit Design by Shyam Tiwari

Detect Total On-Time -  02/04/99 EDN Design Ideas:  NOTE:    Page includes several designs.  Scroll to find this one.  The circuit in Figure 1 provide as a voltage that is directly proportional to the sum of the total on-times for a number of positive pulses that occur during the interval between sample signals.  When a positive pulse arrives at the control input to switch IC 1A, a constant-current source charges capacitor C1  through IC 1A for the duration __ Circuit Design by Richard Nachazel, Vista Electronics Co, Ramona, CA

Digital LED Voltmeter -  Measures voltages up to 199.9V with 0.1V resolution.  __ 

Digital Mains Voltage Indicator -  This is a circuit for a digital mains voltage indicator that displays main voltage in the form of a LED bar graph with 16 LEDs.  The first LED indicates voltage level at 50 V and the 16th LED shows voltage level for 280 V__ Electronics Projects for You

Digital Mains Voltage Indicator -  Continuous monitoring of the mains voltage is required in many ap- plications such as manual voltage stabilisers and motor pumps.  An analogue voltmeter, though cheap, has many disadvantages as it has moving parts and is sensitive to vibrations.  The __ Designed by Radio LocMan

Digital Volt & Amp Meter with Temperature Control -  This project was designed and constructed as enhancement to the 0-30V Stabilized Power Supply Project with the DiY electronics hobbyist in mind.  The circuit uses a single PIC  Microchip to perform the Voltage, Current and Temperature conversions and display functions.  The PCB Board uses large  __ Designed by RSABear 2008

Digital Voltmeter -  The IC L7107 is a 3 1/2 digit LED A/D convertor.  it contains an internal voltage reference, high isolation analog switches, sequential control logic, and the display drivers.  The auto-zero adjust ensures zero reading for 0 volts input.   __ Contact IQ Technologies

Digital voltmeter (DVM) -  This multimeter was designed to measure output voltage and current in a PSU, where the current sense shunt resistor is connected in series with load at the negative voltage rail.  it needs only one supply voltage that can be acquired from main PSU.  An additional function of the multimeter is that it can control (switch on and off) an electric fan used to cool the main heatsink.  The power threshold at which the fan switches on can be adjusted using One Touch Button Setup.__ 

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

Digital Voltmeter with LED Display -  This is an easy to build, but nevertheless very accurate and useful digital voltmeter.  it has been designed as a panel meter and can be used in DC power supplies or anywhere else it is necessary to have an accurate indication of the voltage present.  The circuit employs the ADC (Analogue to Digital Converter) i.  C.  CL7107 made by iNTERSiL __ Designed by of this circuit belongs to smart kit electronics

Disconnect 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

Disconnect Load from Low-Voltage Supply -  04/24/03  EDN Design Ideas:  Circuit ensures safety in power-on operation.  Power supplies often include a circuit that disconnects the load when the supply voltage drops too low, such as when a battery is nearly discharged.  A p-channel MOSFET connected between supply and load is the typical approach.  However, a 1.5V single-cell battery or other low-voltage supply is insufficient to fully turn on the MOSFET.  For such low-voltage systems, consider the circuit of Figure 1.   __ Circuit Design by Steve Caldwell

Dot/Bar Rx Voltmeter -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Eight LEDs Make a 100-Division Voltmeter -  09/22/11  EDN Design Ideas:  Use a counter IC to drive two sets of four LEDs.  The circuit in this Design idea makes a voltmeter that reads to 0.99V.  The idea uses a counter IC to drive two sets of four LEDs (Figure 1).  Each of these two sets represents a BCD (binary-coded-decimal) value.  With all of the LEDs off, the voltmeter reads 0V.  With all of the LEDs on, the reading is 0.99V.  Op amp IC 1A generates a predictable voltage ramp. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune University, Maharashtra, India

ESP8266 WIFI Voltmeter Li-Ion ThingSpeak Deep Sleep Datalogger -  The ESP8266 wifI serial modules, are the new HiT, so I had to play with them also.   Here is my very first project with this new-wounder, a wireless WiFI voltmeter datalogger, very usefull for my lab experiments.   when I want to monitor electronics over longer time, and simply check the live result via a web page, no matter where in the world I am at the same time. __ Designed by Thomas Scherrer OZ2CPU

Expanded Scale Battery Volt Meter -  This circuit is used to measure the voltage on a 12V (nominal) lead acid rechargeable battery system.  it was specifically designed for use in solar powered systems, but is general enough that it can be used for automotive or other 12V systems.  Lead acid batteries normally spend their working lifetime in the voltage range of 11-15 Volts.  This meter circuit __ Designed by G. Forrest Cook

Expanded Scale Voltmeter -  I have a 12v batter charger I put together many years ago from bits and pieces found in the junk box.  its been a good little light duty charger, but was lacking any form of battery monitoring, so I decided to give it an upgrade with a expanded scale volt meter and amp meter__ Home Power Magazine

Expanded-scale indicator revisited -  08/08/02 EDN Design Ideas:  The visualization aid that a previous Design ideas describes allows only the expansion of the upper end of the scale (Reference 1].  But what can you do if, according to your project requirements, you need to expand the middle region of the scale? Figure 1a illustrates the challenge.  A voltmeter comprises a 100-A dc meter and a series resistor __ Circuit Design by Abel Raynus, Armatron International Inc, Melrose, MA

Expanded-Scale Voltmeter Uses Just Two Parts -  01/20/94 EDN Design Ideas:  The expanded voltmeter doesn't require trimpots to obtain usable accuracy or require the tedious selection of Zener diodes.  This circuit consists of only two parts and a5V meter.  The circuit is completely linear and requires no calibration except the rare mechanical zeroing of the meter.  By using __ Circuit Design by DD Cantrell, North Valley Research, Los Molinos, CA

High Voltage Stun Gun -  This device produces high voltage pulses discrupting muscles and nervous sYstem, leaving anyone who touches it in a state of menthal confusion.  Can be used agains ferocious animals or attackers, BUT REMEMBER, this device may be illegal in your state (for eg where I live, these devices are banned).  it is quite dangeros for peoples experiencing cardiac problems, and for electronic equipment (like peacemakers) , since it generates some RF.  Don't attept irresponsible actions with this device, it is not a toy. __ Designed by Jonathan Filippi

High-Impedance voltmeter -  An ideal voltmeter has infinite input impedance, meaning that it draws zero current from the circuit under test.  This way, there will be no "impact" on the circuit as the voltage is being measured.  The more current a voltmeter draws from the circuit under test, the more the measured voltage will "sag" under the loading effect of the meter, like a tire-pressure gauge __ Designed by EETech Media, LLC.

High-voltage Amplifier drives piezo tubes -  7-Dec-04 EDN Design Ideas:  Piezoelectric tubular positioners that drive manipulators in scanning tunneling microscopes require high-voltage, low-current drive circuits.  The circuit in Figure 1 can drive high-resistance, low-capacitance piezoelectric loads at a -3-dB bandwidth of 6 kHz.  it offers a low-cost alternative to commercial driversPDF has several circuits, please scroll to find this one __ Circuit Design by Bipin Duggal, Netaji Subhas Institute of Technology, New Delhi, India

Hippasian nonlinear VFC stretches dynamic range -  19-Feb-09 EDN Design Ideas:  A voltage-to-frequency converter uses square roots to extend dynamic range by orders of magnitude __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

How to Use the MAXQ2000 as a Voltmeter -  App Note 4194-- 3/24/2008 -- (add 5/08) __ Maxim Integrated

ICL7107-DigitAL LED VOLTMETER -  This digital voltmeter is ideal to use for measuring the output voltage of your DC power supply.  it includes a 3.5-digit LED display with a negative voltage indicator.  it measures DC voltages from 0 to 199.9V with a resolution of 0.1V.  __ 

Input Attenuator for the Digital Audio Millivoltmeter -  if you'd like to be able to use our Digital Audio Millivoltmeter to measure AC voltages up to 140V RMS, this add-on project is the answer.  it's a simple switched input divider which lets you add 40dB, 20dB or 0dB of attenuation ahead of the meter at the touch of a knob.__ SiliconChip

Latching Regulator Prevents Deep Discharge -  03/16/95 EDN Design Ideas:  To avoid a deep discharge that can shorten or destroy a rechargeable battery's life, you need to remove the load at the point of complete discharge.  Because a battery's terminal voltage recovers after load removal, you can't simply disconnect the load when the voltage dips below a threshold and reconnect it when the voltage returns above that threshold __ Circuit Design by Doug Vargha, Maxim Integrated Products, Sunnyvale, CA

LED display Digital Voltmeter -  This digital voltmeter is ideal to use for measuring the output voltage of your DC power supply.  it includes a 3.5-digit LED display with a negative voltage indicator.  it measures DC voltages from 0 to 199.9V with a resolution of 0.1V.  The voltmeter is based on single IC L7107 chip and may be fitted on a small 3cm x 7cm__ 

LED display digital Voltmeter -  This is an easy to build, but nevertheless very accurate and useful digital voltmeter.  it has been designed as a panel meter and can be used in DC power supplies or anywhere else it is necessary to have an accurate indication of the voltage present.  The circuit employs the ADC (Analogue to Digital Converter) i.C.  CL7107 made by iNTERSiL. __ Designed by Smart Kit Electronics

LED Volt Meter -  Here is a Simple LED Volt meter to Monitor the charge level in Lead Acid Battery or Tubular battery.  The terminal voltage of the battery is indicated through a four level LED indicators.  The nominal terminal voltage of a Lead Acid battery is 13.8 volts and that of a Tubular battery is 14.8 volts when__ 

LED Voltmeter -  Measures voltages up to 199.9V with 0.1V resolution.  __ 

LED Voltmeters 20 & 30 LED's -  These are Basic Expanded Voltmeters based on the National LM3914 chip.  They can be Switched to either Bar or Dot Mode.  The 20 LED one has a Minimum 2.5 volt range for Full Scale and it can be adjusted to Much Higher voltage ranges with the input potentiometer. __ Designed by G.L. Chemelec

Logic Gates Form High-Impedance Voltmeter -  05/26/11  EDN Design Ideas:  Estimate voltages across high-value resistances.  You can use the circuit described in this Design idea to estimate voltages across 10- to 100-MΩ resistances.  it also works for reverse-biased diodes.  The common CMOS gates in Figure 1 have an input threshold voltage in which the output swings from logic zero to logic one, and vice versa.  The threshold voltage depends on the supply voltage (Figure 2).   __ Circuit Design by Raju R Baddi, Tata Institute of Fundamental Research, Maharashtra, India

Low Power LED Voltmeter -  This is a low power voltmeter circuit that can be used with alternative energy systems that run on 12 and 24 volt batteries.  The voltmeter is an expanded scale type that indicates small voltage steps over the 10 to 16 volt range for 12 volt batteries and over the 22 to 32 volt __ Designed by G. Forrest Cook

Low Voltage Alarm -  NE555 Low Voltage Battery Disconnect Circuit __ Designed by Aaron Cake

Low Voltage Audio Amplifier -  This experimental (3) transistor class A audio power amplifier delivers 25mW into an 8Ω load, or 50mW into a 4Ω load using only a 1.5V power source.  At such low voltages, there are many issues to consider and much to learn.  To the best of my knowledge the following information is new to the world.  Background Months __ Designed by Jim Keith

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Voltage Detectors / Sensors / Monitors:  #'s - C      D - L      M - Z


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