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## Load sensing circuit for AC line

One of the simples methods of sensing loads is to use a low-Ω resistor (0.1Ω or less) in series with a load and connect 5/230V transformer with the 5V winding in parallel with this resistor. By doing this you have gain of ≈44, and now this signal can be used by an ordinary comparator to acitvate something (relay, LED, ..) .. (...)

## load sensing circuit help required

I am in need of a circuit which can sense a preset load on Ac line(mains) and when the load exceeds the preset value it automatically turn on a 12v relay to shut down the ac mains circuit.and when the load falls bellow the preset value it again turn off the 12v relay to turn on the ac mains (...)

## Current Contoller Circuit

I want to make a current controller circuit for a DC Brushed Motor. Can anyone suggest circuitry? You may start from the circuit shown in the attached figure. The load in the figure can be replaced with DC Brushed Motor. The output of the current sensing circuit is connected to an ADC (...)

## help me sinewave is changing with load

Hi friends i am working on sine wave off line ups.I have written the code i am sine wave at no load as i am loading the inverter its shape is changing to square wave at 60 W bulb load initially its shape is changed to "D-shape" as i am loading the inverter it is complety going to square wave.I dont know what is the cause. (...)

## circuit for current sense or current monitoring

i have searched a circuit for current sense or current monitoring and i have come across a circuit which i have attached. i tried to figure out that how this circuit works and it goes as follows. 1st consider that load is not present. then Va = Vb and and transistor is in cutt off state where Vc (collector voltage) = (...)

## voltage sensing circuit

Hi, you can connect the load like you say and in parallel you can connect two resistors in serie, 10K and 1 K and then monitor the voltage measuring the 1K resistor. Or you can change the values of the resistors for another level of voltage in one of them and after that you can apply a bridge of diodes for generating DC. I hope it helps. Alb

## OVP,OIP and OLIP in SMPS?

In SMPS design of attachment file, I found that Overvoltage and Overcurrent are sensed from secondary of Flyback trasformer.Overload current sensing is from primary.I would like to know some questions about the circuit like this above. 1.Can current and voltage sensing circuit be connected to either side (...)

## AC Current Sensing Problem : Nonzero Nocurrent Output

CT need a resistor load (fixed value resistor specified by CT manufacturer), look at application circuit suggection or electrical specifications of your CT. Do you have that resitor load? Vithout proper termination your reading could be in error also with current passing if load side is open circuit by (...)

hi, I m currently working on project named, Butt Welding controller.... In this pro TRIAC (BTA41) is used to control the load voltage(AC).... 89c52 microcntroller is used to provid Variable voltage To fire the TRIAC.... Via DAC0808.... Now finally i want to disply the ACTUAL load vltage on my display. Here i m using ADC0804 to rread t

I am doing a project for a module that controls the switching of a few different loads. A microcontroller will be controlling most likely a MOSFET to switch the current to the load. The module must be able to "sense" the load, in that the microcontroller must know if a a load open-circuits - such as a bulb (...)

## Current sensing - current safety into the circuit

if you don't need to be accurate with the current, you can make your own. Best is a toroid, wind maybe 2 turns of line voltage on it, take the active wire complete with its insulation. then get some Cu winding wire, and wind on 50T at least. Now you will get a voltage on this secondary winding when current flows through the active wire. You wi

## Solid state relay disaster

I need some help here.. I have a voltage sensing circuit that is supposed to operate an AC contactor (solenoid type) when the voltage reaches a certain threshold. This portion works fine but the AC waveform to the coil looks terrible. Very distorted at the zero crossing and top looks chopped. The contactor is also chattering. I selected a zero

## Current sensing <150 amps

A very cheap method to make a CT is to use a small transformer and remove its secondary low voltage winding. Then use a single turn of think wire to serve as high current primary. The high voltage winding can now be used as current secondary with a suitable resistance as its burden (load, shunt).

## Zero Cross Detector circuit and program using AVR?

hi tehmid i used this zero croosing detector for voltage, it is accurate,but i need zero cross detection for load current.. if i use CT then it have two terminals, but this circuit have three terminals.. how i can use it.please help me

## Help! Can someone clarify to me how sense current with EI current transformer ?

Help! Can someone clarify to me how sense current with EI current transformer ? it o\p we for over load sensing ..... pl help me

## supercapacitor and mosfet / voltage sensing switch (energy harvesting) considerations

are there differences with the supercapacitor position among the setup: *full bridge rectifier (4 1N60 germanium diodes) *dc/dc converter (TPS61200) *supercapacitor (Cellergy 20mF 4.2V Ultracap with ESR = 0.36milliohms) **full bridge rectifier AND dc/dc converter using LTC3588 a.) piezo/other transducer -> full bridge rectifier -> supercap

## How To Disable UPS Auto Turnoff?

Hello everyone, I have a Wep emerge 500VA PC ups which i usually used for my pc. But often I want it to charge my mobile using charger when mains power is not available. But the problem is, when the load is very low, the ups automatically turns off after a few seconds (from cold start). Do you have any ideas sothat i can tweak any parts to work

## variable resistor placement

If you want any accuracy the voltage drops across the recitfier diodes will be a problem. The diode drops will be nonlinear and vary greatly with temperature. I would place the load resistor (fixed + small variable in series) directly on the secondary of the transformer. Then I would use an op-amp rectifier if you want to get DC out. Maybe you

## feed back current sensing for pic microcontroller

So you want to measure alternating current, right? There are two ways. One is to use a shunt resistor, and the other is to use a transformer. First approach has advantage of being simple and cheap, but also contributes power loss in circuit. Resistor can be really small (like 0.2R or something). Then you amplify and measure the voltage drop acr

## short circuit protection at 60v .5A

it will just be a digital output where the load(realy most probably) will be driven using a fet for transistor. the input supply will be from 24 to 60v but we have to implement a limit of .5A at 60V. at other voltages also shortcircuit protection must be there

## short circuit/over voltage/over load protection in smps

Since it's half-bridge, for short-circuit protection, you should use a current transformer in the path of the power transformer. For overvoltage protection, step down the DC bus using a voltage divider, eg, by a factor of 100. So, 300VDC gives 3V at the output of the voltage divider. Say, you realize that overvoltage is defined for voltages greater

## IR2130 Current Sensing Problem

Hello, I am driving motor with IR2130(3phase) and controlling the IR2130 with PIC. I am using 5 12v/7a batteries. The system is working like this: First I am starting the motor to run to one direction for 2 seconds. I am measuring the current. Then I am making the motor to run in reverse direction for two seconds. And I am measuring the current

## PIC16F877A Based Ammeter

hello But I know that Current Transformers with op-amp circuits can be used to interface microcontrollers. What I need is a current sensing circuit interfaced to ADC pin of PIC16F877A. I fund a schematic of "Ideal rectifier with an Operatioanl Amplifier" and tested it with circuit Maker Student CMS60. If you use a (...)

I assume that you mean a power inverter (DC to AC "step-up" converter). You would need a means of sensing the current. You can use a shunt for this or a current transformer or a hall-effect sensor. A hall-effect sensor may be best, but is likely to be very expensive. You can use a shunt, but keep in mind, the voltage and power loss introduced. T

## DC to AC 220v power inverter over load circuit diagrams on 500va to 5000watt

You would need a means of measuring the current and determining if it is within the overload limit. Shunt may be used. But with increasing power, required resistance will be VERY low to keep losses low. Keep the losses in mind when designing the circuitry. You may look at other current sensing methods, such as hall-effect sensor. Hope (...)

## Help with shortcut protection circuit

One circuit you could use is: Sense the current flowing through (a shunt may be used, or you can use any other type of current measurement device). Compare the value against a preset value. If the measured current < reference current, switch on a MOSFET that permits current flow through the load. Keep on sensing the current. If the current (...)

## Small load cell to interface a microcontroller.

load cell will give analog output. For processing the information, you have to connect ADC between load cell and microcontroller.

## Weird problem of usb charger circuit. Urgent !

It seems your regulator TL2575 is maybe not configured properly. Have you checked the output of the regulator with a multimeter, when it is connected with load??? Try using LM7805. It requires no voltage configurations...

## constant current circuit (4A) with unstable Load

hi everyone i need to develop constant current circuit (4A +-10%) in temperature range (-45 to 85 C). i mean constant current in temperature range, circuit will work 1 sec. supply voltage 28 V. main problem that my load can be from 1 to 7 ohm (random). i don't know if anybody here had experience this problem and should please guide me (...)

## Help me in Programming for sensing current and voltage using P89V51RD2

Guys .. i need to write a C code for sensing the voltage and current using the microcontroller P89V51RD2.. in LCD i want to display the exact voltage value i.e. like 8.2V and also the current..and i also want give an reference voltage and current and when the V,I is less than the ref value i have to cut the supply to the load else give supply.. for

## Need help with Philips TV 21CT9460/73S

Another tip. Being the flyback circuit the one that draws most of the current, cut the connection ( or thrace ) between the capacitor after the rectifier and the HV generator circuit and replace the load wit a bulb lamp 230 V 40 or 60 W ( 40 w for 14 or 16 ", 60 W if higher ). Turn On the TV and verify the voltage across the lamp. If (...)

hi the schtematic given is only a block digram for this purpose u can use feed back amplifier for given the constant input. at load should have to connect the volt meter and make your desire output as a 0 volt so the variations occurs u should read directly, as same for the ampere meter.

## monitoring battery voltage

Hi, you can use simple comparator, like a LM393, all is depending from this do you have some available part in your circuit that can be used. The diagrams from IanP is good, but have one big disadvantage, the LED is on when the voltage is in nominal range. There are two problems: 1- Via the led you will have a current that will be extra load, and

## Why I see 10A current pulse?

load is pure incductuve and this is exact application circuit. Drawing from scop screen. I didn't show the Mos driver.

## alternanting current regulator

Hi Cars have a voltage regulator systems which fixes the output voltage of their generator to the desired value. It basically consist in a transformer where the regulator monitors the secundary volage and according to the load in the secundary circuit increases or decreases the voltage in the primary circuit of the transformer. You can (...)

## remote control using telephone line

Ok, I am a little confused. What does item #1 mean? Are you saying that the phone line is captured immediately at the first ring without the relay being energized? If this is the case, then I think you need to either reduce the value of the series capacitor on the ring detection leg or add additional resistance to only that portion of the circui

## How to build Constant Current PSU

Hi I am building a CV-CC supply which would output a 50ms pulse of the set output current to a load which would be up to 5 ohms. I will set a current of 1Amp (using fixed resistor prior to the load) by replacing the load by a short circuit,vary the voltage and then connect the load for actual experiment. (...)

## Three phase current monitioring how to

hello , I want to generate 4 pulses at different load of a diesel generator say 1st at 60A second at 70 and third ad 80 and then at 90A. Please explian the circuit/hardware for this. Will CT with shunt will be correct method or is there any other easy solution to this. regards

## pnp transistor current limiting

I'm driving a load with a pnp transistor. The current is 1A max, the voltage is 24V. I want to turn off the output above this current but i don't want to use a power resistor and do not want to use a complex circuit. Can you suggest me simple yet effective current limiting scheme for this task without using a power resistor? Thanks.

## 1-5 volts to 4-20 ma?

Whether to connect the sensing load to ground or not depends on where the supply source comes from. Many sistems use an external Vcc to power the load. Voltages up to 24V may be required if using many loads in series. Nothing wrong if you intend to use only one sensing load. Please also take (...)

## Measuring DC Amps using ATMega16

Hi, I am a newbie and am trying to design an Amp-Hour meter using ATMega16. My main constraint is that I need to measure on the High side. The second constraint is that the high side current measurement ICs are not available locally in Karachi, Pakistan. The current measurement is for a UPS battery (12VDC car battery). Current sensing is to b

## current and voltage sensor

I do not understand your diagram but assume that you want to measure the terminal output voltage of some solar panels in series (40 V) as well as the load current out of these panels. To measure the voltage you must divide the 40 VDC down to 5 V. I assume that your A2D can handle a 0 - 5 V inputs The divide circuit is simply two resistors in serie

## Design of a Comparator

this means differential amplifier with ratio between driver to load transconductance (Gm/Gload) <10. In principle from your spec follow that even simple complementary (i.e. P-type + N-type sensitive input) regenerative amplifier (without analog preamplifier stage) can be enough.

## controlling a 120A power source

Remote sense isn't remote control, it's just a means to compensate voltage drops at the cable by sensing the voltage at the load. A remote controllable power supply should have at least terminal pairs for voltage and current setpoint. If your instrument doesn't have it, then it's probably not designed for remote control.

## Beginners question about variable output voltage switching topology

A buck regulator can easily be made to control the output from 0.0V to max, in a smooth fashion, this is never done however for two reasons; 1, if the buck switch fails short full volts will be applied to the output (lots of smoke in the load) & 2, a straight buck converter provides no isolation - so if you touch the o/p you will get a mains shock

## Solar Charge Controller Design - Help Needed!

1. At first I would think it is logical to charge at 14.5 V. It automatically cuts off charge when Spec #1 is reached. However you will find that charging current is greater when you apply a higher volt level, say 24 V. My solar panels had enough cells to output that amount, with no load attached. I think the manufacturer experimented until they

## UPS Whine/Buzz/Squeal when Water Heater is turned ON

It might not indicate going to battery because it is still using mains, not going to full on-battery mode. Your UPS has Automatic Voltage Regulation, which means that it regulates the mains output voltage when the mains input voltage is out of range (a bit too low = brownout). Do the UPS socket and the water heater share the same mains wire back t

## Measuring current using CT and microcontroller

Here is a good example of how to do it using a series shunt

## energy monitoring using pic16f877a_any suggestions for sensors?

energy monitoring using pic16f877a_which sensors to use? Hi all, I m trying to build an energy monitoring application. I have to measure power consumed in a domestic environment, and power generated in a solar panel. I am emulating the domestic environment with a load built with two 40W lamps. I have some doubts regarding the sensors that i

## Struggling to Understand...

Hi, I have seen this foldback circuit and would like to use it however I am struggling to understand how it works? 90889 The rather brief writeup with it says: In normal operation, Q1 is saturated. When load attempts to draw more than this saturation value, base current of Q1 cannot maintain saturation so vol