Measurements of the current flowing through a circuit

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3answers
138 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 ...
4
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1answer
72 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
263 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
37 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 ...
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1answer
66 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
98 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
66 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
41 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 ...
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1answer
34 views

12Vdc 5A Power supply electricity consumption

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
72 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 ...
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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
322 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
43 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
43 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)? ...
0
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2answers
102 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 ...
2
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4answers
99 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 ...
2
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4answers
308 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
38 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
54 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
55 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 ...
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2answers
93 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
63 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 ...
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2answers
54 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
71 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
51 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
99 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
65 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 ...
0
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1answer
59 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
130 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 ...
0
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0answers
113 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
111 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 ...
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1answer
31 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
38 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
65 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 ...
0
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1answer
145 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
51 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
25 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
78 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
99 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 ...
5
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1answer
95 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 ...
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2answers
115 views

How to measure current with an analog multimeter? [closed]

I need measuring the current through a dc motor with an analog multimeter, but I don't know how to select the correct function to that. The meter is a FT-360TR. I know it can measure currents of ...
0
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1answer
63 views

3A Current Distribution

simulate this circuit – Schematic created using CircuitLab I am using a 5V 3A wall adapter. I have stripped the output end and connected it to a terminal block. I am rerouting the current ...
0
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1answer
86 views

Usb input current requirements for a power bank

My project is to take solar power from a 6w/6v panel, run it through a buck circuit tuned to 5v and charge one of the LiPo power banks. I perceive a buck circuit would do better at efficiency than a ...
0
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1answer
48 views

Computing Power Requirement For Solar Setup

In relation to this question: Solar power wattage requirement I'm trying to get to the math of understanding my wattage for my plan solar-setup. I would like anyone here who knew can correct me on my ...
1
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1answer
361 views

Converting 100mV AC to 1V DC

Hey guys I am looking for a circuit where I can convert 100mV AC to 1V DC and then feed it to my microcontroller's ADC pin. Can any one suggest any circuit to achieve this? I want to interface a ...
0
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0answers
60 views

Peak and leakage current detector

Hello I am trying to make peak and leakage detector for LCD shutter. I have specific parameters known : Voltage from 5V to 12V bipolar square wave. Testing is at 60hz Peak current ~30mA leakage ...
0
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1answer
114 views

Short circuit current in transformer

When transformer secondary is short circuited, what would be the value of current flowing through short circuited side? Shouldn't it be infinity ideally? If yes, is it only due to large cross-section ...
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2answers
163 views

Wiring an ammeter with no shunt [closed]

I am new to electronics and trying to make something easy to start with. Bought one of those voltmeter and ammeter AIO from ebay (LINK , see item #5) and want to hook it to a 12V battery (4Ah) to ...
0
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2answers
87 views

measuring the current for battery monitoring project

I have to build up a battery cell(single) monitoring system which can calculate the cell's (single) efficiency which should be atleast 0.1% - 0.5% accurate. The cell would be charged over a couple of ...