Measurements of the current flowing through a circuit

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2answers
88 views

Measuring very low current

I have asked here a month ago regarding measurement of very low current. I was told that Amper-Meters today has this resistance in series that will cause a voltage drop, hence you can't measure a very ...
0
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1answer
24 views

Feedback Gain Loss of Transimpedance Amplifier

I have designed a single-supply (3.3V) potentiostat that initiates electrochemical reactions, converts the generated electrochemical current into a voltage via a transimpedance amplifier (op-amp used ...
0
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2answers
57 views

What kind of a relay do I need? [closed]

I'm building a home automation unit using arduino. Most of my appliances can be controlled using a 5V 10A relay, but there is one power hungry appliance. Its a 1TON split AC unit which is currently ...
1
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1answer
32 views

Clamp Meter Working Principle

Basic theory of clamp meter to measure rms of current wave. What I have in mind is that wire creates the changing flux that induces voltage in the meter.This voltage is calibrated ? Also how does the ...
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1answer
73 views

Attenuation of Input Signal

Schematic Simulation Model The circuit is simple , it includes a 3mA Sine Current source in parallel to a Resistor that converts it to voltage and supplies it to the differential amplifier with ...
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2answers
29 views

Estimating battery capacity remaining from SLA connected to motors

I have an SLA battery, at say 10 Amp-Hours, connected to 3 high power motors. Each motor can draw up to 10 Amps each (worst case / max power). Using Q = It as an ...
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3answers
58 views

Sign of current through a voltage source

simulate this circuit – Schematic created using CircuitLab I am a total newbie to circuits, so please forgive my naivety. My question is the following: When I simulate the above circuit ...
0
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1answer
45 views

Current monitor shows overload even for small load

I have a current-shunt monitor using INA202 between a 5V power supply and loads. The current monitor should turn off a MOSFET switch and disconnects the loads if the load current goes over 150mA. I ...
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0answers
18 views

Current harmonics measurement for building automation and energy monitoring

I want to measure current ranging from 1mA to 30 A approximately. I want to use both shunt(low resistance current shunt) and rogowski coil. The shunt is for large currents and the rogowski coil is to ...
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3answers
156 views

confusing current readings

I know that Ohm's Law is V = IR but I am getting some very confusing current readings from multiple multimeters. Here is my very basic breadboard configuration: V = 6v R = 200 Ohms I = Should ...
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1answer
142 views

Measuring currents between 100pA to 100uA

I want to measure absortion/resorbtion currents of dielectric when applying 1000V, 1500V, 2000V. I have made a small currents measuring device using a LOG114: I use : LOG114 with 1uA reference ...
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2answers
275 views

Measuring current drops voltage?

We have some pcb in which contains an MCU ,and some WiFi module . Usually at start, the board takes 70-100mA with 3v3 . It gets its current from the UNO board connected to a mac. It works great like ...
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1answer
45 views

Avoid heating with high current

I am new to electronics and just tinkering with it first time. I have laptop charger with 19V/3.42A and connected to 12v regulator and 3.3v regulator to get two voltages - 12v and 3.3v. I am going to ...
2
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1answer
70 views

Understanding a current sensor circuit

I'm struggling to see how the output of this circuit is $$V_{0} = {I_{s} R_{s} R_{L}/{5k}} $$ My work thus far: I understand the voltage into the base of the BJT is $$I_{s}R_{s}$$ I understand the ...
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1answer
101 views

Circuit to detect amperage?

Is there a circuit which can detect how much amps are flowing through it, and if the amperage falls below a certain level to output some signal? (e.g. to direct the voltage to a different output) ...
0
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1answer
84 views

Driving IR LEDs using PWM - measuring current & current source questions

For a project I'm currently working on, we're trying to drive 940nm IR LEDs (Kingbright L-934-F3C) using PWM, regulated by an Arduino Uno. We've run into several issues during our prototyping process ...
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1answer
46 views

Problem Measuring Current in a High Voltage circuit with arduino

I 'm measuring a current in a resistor as shown in the picture below. There I'm using a voltage substractor with an LM324 Operational Amplifier. I'm having trouble in the real World when the voltage ...
0
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1answer
36 views

12Vdc 5A Power supply electricity consumption [closed]

i am using a 12Vdc 5Amp regulated power supply to power some Led lights.The total consumption is 2Amp. I need to understand if the power supply consumes less electricity(230Vac) if i do not use all ...
0
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1answer
99 views

Measuring AC voltage (0.333vac max) using a 10 bit ADC on Atmel ATMEGA328

new to this so please be kind. want to measure AC current in domestic supplies using an atmel ATMEGA328P chip wit the best resolution possible I need to use the split core current transformer ...
0
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0answers
29 views

3 channel vs. 4 channel 120/240 power meter

So I live in the US, where we have center tapped power for residential use, with two hots and a single neutral wire. My question is what would be the potential effective difference in power ...
2
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2answers
339 views

Could you explain how this current measurement circuit works?

I have a schematic for current measurement, but I don't really know how can I calculate the output of it. The op-amps are on +-12V. The output of the circuit is 0.2*I(Rs) [V] (--> this is what I don't ...
2
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1answer
46 views

Protecting current measuring shunt resistor from overcurrent

To measure the current "drawn" by a 12V PTC heater element and to be able to switch it on and off from an AVR micro controller, I have come up with the circuit below. The PTC heater element has ...
2
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2answers
45 views

How responsive are current transducers?

We are using an (XD-V5-01) to measure an AC current but what we are not sure of is how responsive devices like this are. Do they accurately reflect the current being measured instantly (100-200 ms)? ...
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2answers
125 views

Oscilloscope measuring current that flows a few milliseconds

Is it possible to measure current that is flowing for 2 or 3 milliseconds inside a circuit through oscilloscope by measuring the voltage drop across a resistor ? The supply voltage is generated by ...
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4answers
111 views

Sensing current upto 2A w/ high resolution

I'm trying to sense a current that will flow in a motor (current shouldn't exceed 2Amps), and I'd like to have a high resolution on this measurement. I was hoping on using the ACS712, but it says the ...
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5answers
355 views

Measuring a huge resistance on low voltage

I was thinking on this theoretical experiment for a while, but nothing useful came into my mind. We have a "resistor" (rather a material like plastic) with a resistance expected to be very high, say ...
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1answer
43 views

Regulate and verify an AC current to test a current transducer sensor

Firstly my background in software so this is a bit of foreign territory for me. I have the requirement to monitor an AC current between 0 and 3 Amps. The plan so far in to use a non invasive current ...
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2answers
58 views

Current measurement on low resistance sources

Most of the devices to measure current at micro amps level or lower recommend a input resistance of more than 1kOhms. (As for an example , shorting the ammeter leads, which is essentially what happens ...
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2answers
57 views

Voltage on the secondary of current transformer

We know that current transformer is used to step down the current of the primary side. So basically it is a STEP UP transformer. Also we say that current transformer basically works on close to short ...
2
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2answers
109 views

Current Shunt Vs Current Clamp Meter - 15% difference Which one is right?

I have a variable AC power supply. 0-12V 0-1800A 60hz. I have always been told to trust the current shunts and not current clamps when measuring current. The current clamps are supposed to accurate ...
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3answers
66 views

What could be the voltage of this common DC motor? [closed]

Below is the picture of a common DC motor usually used in electronic toys. This motor is quite common so I guess someone may be knowing it's voltage and how much current it draws. I could've tested it ...
0
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2answers
55 views

Power measurement on neutral instead of line

what is the advantage or disadvantage of measuring the power on neutral insted of line in a single phase wiring. Generally I have observed that metering chip is given input from line to its Vin or ...
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0answers
77 views

Current sensing in H bridge for Stall detection-Purpose of Diode

I have a circuit, which is powered from two 1.5 V AA battery. It has a MCU and PNP - NPN Hbridge for driving motor. The motor (RF-300CA-11400) datasheet is here in this Link. The Motor will be turned ...
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2answers
55 views

How do I determine my burden resistor for my current sensor?

So I've got a -12v +12v ADC input limit and I've got a 200 turns ratio current transformer. My input Max current is 30A which is stepped down to 150mA. How do I determine the right burden resistor so ...
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0answers
36 views

current feedback design

How do I select the current sensing resistor \$R_{56}\$ with following details: Feedback threshold voltage is 0.5V. DC input voltage 400V. AC output voltage 230V. output power is 500W. operating ...
2
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2answers
113 views

DC non invasive power measurment

For one of my PhD project I have to measure power consumption from different electric wheelchairs during various tasks and recor these measurment for later studies. I have not much experience in ...
0
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1answer
69 views

Measuring current using low side shunt method (MCLV-2 board)

I am trying to measure the current through the MOSFET switch M1 using low side shunt resistor method (on MCLV-2 dev. board). I can read the signal `Vout' on the analog input of a dsPIC33F MCU. I ...
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1answer
63 views

chosing the right Hall effect sensor

For a student project, I need a Hall Effect current sensor. What I am going to do is to charge 8 rechargeable Li-Ion batteries of 3.7 volts in series with 34 volt supply and the buck circuit frequency ...
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2answers
150 views

Drive DC Motor with H Bridge(H Bridge turns off too slow and problem with current monitor)

I have two questions about my circuit, drving DC Motor with H Bridge. The picture below shows my design and how I drive it with signals. For example, when I make the motor rotate forward, I give ...
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0answers
135 views

variable gain amplifier for ACS712 current sensor

My project requires measuring current ranging from 30mA to 500mA. Im using ACS712 (5A)current sensor for this purpose. Since the sensitivity of the sensor is typ:185mV/A, measuring current as low as ...
0
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0answers
122 views

How to measure microvolts of electricity in plants?

I'm trying to measure electricity in plants, to do something a bit like this: http://www.treehugger.com/culture/organic-electronic-sounds-from-plants-sonic-artist-mileece.html Basically, plants ...
1
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1answer
35 views

Fundamental difference between DC IV measured current leakage and AC CV measured conductance

I am a physicist with an general EE measurement question, thanks in advance for the advice! I am measuring the properties of a majority carrier diode that I am designing, and usually just take DC IV ...
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0answers
39 views

connecting AC signal 250V to DC signal 3V3

I want to measure an AC and DC current about 250V for AC and 3V3 for DC, i want to use an LT1787 (High Side Current Sense Amplifiers) with amplier stage and DSP to acquire the value. The problem is ...
2
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1answer
67 views

Buffered feedback circuit analysis

I saw this circuit while going through some circuits and have been trying to solve it since. I get confused at multiple points while solving for the current. Since there is a buffer for ...
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1answer
197 views

how to resolve LM358's huge error as a current sense differential amplifier

Ive built a current sense differential amplifier that measures the voltage across a 1 Ohm resistor to give me a reading for the current through it. Ive connected it as follows, all resistors are ...
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2answers
64 views

Confused about this KVL equation (AC circuit)

I have the following circuit below, with part of the solution: I need to find Z. I'm confused about the KVL equation below (fourth line): If I understand correctly, they used loop analysis: with ...
0
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1answer
26 views

Peak current requirement for switching logic

Is there a way of estimating peak current requirements for sets of logic gates? This is to qualify the regulator. I have a Gumstix Parlor board with a 1.8V regulator (MIC5247) at 150mA on it. This is ...
2
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1answer
80 views

Measuring GameBoy power consumption

I am currently developing my own homebrew GameBoy game and I would like to try some tricks to reduce power consumption (for the sake of learning). The GameBoy has a HALT instruction that will stop ...
0
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1answer
114 views

LM311 Current Sensing Switch

I need to create a current sensing switch and am looking for ideas. I have very little experience with op amps / comparitors (as you'll see) but this seems to be the way to go. I am monitoring 24VDC ...
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1answer
102 views

Recommended Layout for Parallel Current Sensing Resistors

I'm working with 12V DC systems and high currents (up to ~40A). In order to meet the wattage and price requirements for my design, I'm using two parallel sense resistors. The IC I'm using for sensing ...