Questions tagged [current-measurement]
Measurements of the current flowing through a circuit
1,060
questions
0
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1answer
86 views
Will a light bulb work the same on a car battery?
So I have an incandescent light bulb that is rated for 100W at a voltage of 220V. So, I calculated that the resistance of the bulb is 484Ω.
I wanted to connect it to a car battery (24V). I know most ...
0
votes
1answer
73 views
Can't find non-invasive dc milliamp sensor [closed]
Why is it impossible to find a non-invasive DC current transformer in the milliamp range that is split core (can open and close around wire)?
I would like to sense when a wire is carrying current or ...
0
votes
2answers
60 views
Detecting very high voltages
I work for a plastics molding company and we manufacture containers that we need to verify do not have holes in them. I am looking design a fixture that will apply a very high voltage (about 15-30KV) ...
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0answers
36 views
Allegro ACS71020 unable to read voltage SPI register
Hi I'm trying to read from the registers of the ACS71020 over SPI, but I can't seem to get any values other than 0. The only time I am able to get anything other than 0 on the MISO line, is on the ...
0
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2answers
85 views
Measure DC current with current transformer
Is it possible to measure DC electrical currents with some type of split core current transformer?
Or it is only for varying currents?
EDIT
Considering a zero-flux CT, could someone show me the basic ...
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0answers
41 views
Current sense amplifier IC for the range 1uA to 1mA
Can anyone suggest reasonably good current sense amplifier ICs that is capable of measuring current in the range of micro to mill-amperes (say, 1 μA to 1 mA)?
Thanks!
2
votes
3answers
101 views
Current sense resistor for high voltage
I have a 5KV DC output from a Cockcroft-Walton multiplier. The current is around few microamps as per the simulation. To prevent discharge, the 200Mohm resistor holds the voltage of the Cockcroft-...
1
vote
1answer
72 views
Can you please help me solve this circuit?
So I'm trying to solve for \$V_n\$.
the way I solved it is by:
$$4I_x5+ 15I_x+ 5I_x= 15$$
$$I_x= \frac{15}{40}$$
then \$v_n= 7.5\$
What do i do wrong ?
6
votes
1answer
172 views
Charge, Voltage, or Current? What can be measured with the highest SNR?
Suppose I have a Faraday cup and a certain number of ions hit the detector. What is the highest signal to noise ratio way / circuit to measure this... does one measure the charge (coulombmeter), ...
0
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1answer
81 views
Where did my thought go wrong (electrical circuit )
The circuit on the right has two identical diodes, D1
and D2. These diodes have a scale factor n = 2 and a
value of saturation current IS = 9nA. The currents in
the diodes are as shown.
Use the ideal ...
0
votes
0answers
35 views
Will the measured powers & energies of two 120V circuits == that of the 240V circuit?
I'd like to design a circuit using the STPM34 (2 channel power meter) that can measure either the power and energy delivered on two separate 120V circuits (one circuit Red Wire, other circuit Black ...
0
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1answer
56 views
Building a Bio-impedance system
I currently have a project that has integrated sensors to monitor human health and related biomarkers, my domain is human-performance so giving athletes the tools to get better at their respective ...
0
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2answers
74 views
How to measure small AC currents from mains?
I want to measure AC current from the mains connected to an isolated source - such as a single 10 watt bulb. The standard multimeter measures the current only in DC, so I needed a device that provides ...
0
votes
1answer
45 views
Sensors - How to convert 4-20mA output to temperature and pressure values?
I'm dealing for the first time with two sensors, of pressure and temperature. Both have output of 4-20mA, then I'm using a 47 ohms 1% to convert to voltage. When flows 20mA, 20mA * 47 ohms = 940mV, ...
0
votes
1answer
51 views
Can these small Hall-Effect Current Sensor Modules really handle 30A?
These don't look like the could reliably handle 30A to me. The terminal block is small, the chip is tiny.
Please help me understand what the considerations are when sizing components & traces for ...
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0answers
41 views
DRAM Self-Refresh not the Lowest Power Mode
I have a DDR3L Samsung DRAM on my Laptop. Based on page 23 of its datasheet, IDD6 or the ...
0
votes
2answers
38 views
ACS712 overcurrent consequences
I have a motor that's rated at 28A.
I want to monitor the power it's drawing so I got an ACS712 in its 30A variant. Knowing the voltage and multiplying by the output I get the power.
But what happens ...
0
votes
1answer
57 views
What is the minimum PWM frequency that LT1999-10 can capture with smooth output settling?
I am referring data sheet of LT1999-10,
My PWM signal is 100Hz duty 5% resolution 8 bit
I have a doubt,
Data sheet - 2MHz bandwidth
Is this IC able to capture 100Hz PWM signal? will output of IC ...
1
vote
0answers
36 views
Is it possible to measure pwm load current using opamp based high side current sensing?
I am referring this app note, hope to use as unidirectional current sensing for a PWM load
PWM load - load is a resistor,
PWM signal - 100Hz, 150V.
Load current 18mA
Duty 5% (PWM resolution 8 bit)
...
9
votes
3answers
2k views
How OPA333 withstand 400V bus without burning in this current sensing application?
I went through following app note, where OPA333 is used in 400V bus current sensing application,
also i have seen current sensor which have term called common mode voltage, which is specify the max ...
1
vote
0answers
33 views
Library file error while using a Third party component( INA138)
I want to use the INA138 as a current sensing amplifier but its symbol is not available in Ltspice so I downloaded the .lib File from https://www.ti.com/lit/zip/sbom140 here.
I then opened the file in ...
0
votes
1answer
56 views
Op Amp High Side Current Sensing
I'm trying to build a high-side current sensing circuit with a differential op-amp which can be seen below:
The LT1006 is actually an LM358 IRL(I know it's a peanut op-amp, but it's what I have ...
0
votes
2answers
40 views
Voltage in a circuit with variable resistance and diode in series?
I came across some examples to calculate the current in a circuit with diode and resistance in series. Consider the circuit below:
Current was calculated as follows:
I = (9 - 0.7)/R1
Does that mean ...
0
votes
1answer
66 views
How do I know that enamelled wire is actually conducting the current?
I am trying to make an electromagnet so I bought magnet wire to wrap around an iron core. I am pretty sure that there is a current running through the copper wire because I attached an alligator clip ...
0
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2answers
53 views
How to calculate current drawn by microchips, transistors and diodes? [closed]
So far, I've dealt with only devices like resistors, capacitors and inductors. Calculating the current drawn by these devices is very simply by using the formulas I read in my Physics textbook (e.g. V ...
0
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1answer
69 views
Why INA293 provide discontinuous reading on low duty PWM signals?
INA293 has 110V common-mode voltage
1MHz gain bandwidth
my signal 90V, 100Hz PWM, 10%-25% duty,
load current 30mA max
shunt resistor 5 Ohm
the gain of ic 20V/V
Vout = 30mA x 20V/V x 5 Ohm = 3V
i use ...
0
votes
0answers
33 views
How do I conduct an experiment to find the discharge curve of a lithium ion battery?
I want to conduct this experiment with a multimeter only. What sort of load do I put?
I used a Sony Li-ion Np-BPL battery model and after full charge, I put the battery across a load of 1k Ohm; ...
6
votes
3answers
742 views
Why cap across shunt resistor, input bypass caps and small resistors on current sensing inputs?
I want to build a sensitive current sensing circuit using shunt, and since I also repair MacBooks occasionally, I have some contact with the schematics of real working expensive devices (although ...
1
vote
2answers
42 views
Help needed to determine inductor material/turns needed
I am trying to formulate a circuit to sense current in a standard US 120V AC power line. I'm planning on using an inductor as a current transformer to sense current flow and allow a microcontroller ...
0
votes
1answer
43 views
Microamp-milliamp Measuring Circuit: will my circuit work? Feedback/Advice
I'm developing a device which must be able to measure milliamps and microamps on one of its lines (down to 1 microamp, but also clearly seeing if it's less than 1uA). It's going to be DC of different ...
0
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1answer
50 views
Measuring Current in Coax Cable Using Clamp on Current Probe
I once again find myself needing to measure the RF current in a coaxial cable.
The signal in question is a high power (100W-1kW range) signal which is a stepped waveform with a 5MHz fundemental with ...
0
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0answers
29 views
Current / power measurement using ACS71020
I am having some hard time in understanding and comprehending the value for ACS71020 current and power measurement. In the manual, rms_avg_1 and rms_avg_2 has been mentioned stating that "The
...
1
vote
2answers
53 views
Voltage drop of a PWM signal
Hello so i have a microcontroller that is driving the following circuit:
Both the MCU and the circuit are powered by a 5v power supply, when PAD_PWM and PAD_PWM_return are not shorted ore there is no ...
0
votes
2answers
64 views
Reading +/- 12V with 3.3V micro
I have 3.3V micro and +/- 12V square wave input I need to measure.
As my MCU can only read 0 to 3.3V, I would like to ask the best way to "translate" this +/-12V signal into 0 to 3.3V.
I try to ...
0
votes
1answer
49 views
Measuring the current of a small battery powered device
I am wanting to modify an existing battery powered device, to switch it on and off using a raspberry pi.
To do this I want to make a transistor relay circuit. However, I need to know the current of ...
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0answers
38 views
Rectified DC current measurement using shunt or Current Transformer
I am working on a project to design a controller for battery charging solution.
A 3 Phase delta power (440 Vrms ph to ph) is given to a 3-phase Variac Transformer ( Variac is operated ...
0
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0answers
28 views
Current measurement in MOSFET circuit
In this circuit, the drain current needs to be calculated when S1 opens and S2 closes and remain in this position for long time. In this position, the transistor is in cutoff region i.e Id=0. But the ...
0
votes
1answer
85 views
Can I draw more current from this battery?
I'm looking to build a power box like this one:
The battery that I'll use is 12V 35Ah deep cycle battery, which has an initial current of <= 10.5A:
Devices that I plan to connect are:
On 12V ...
0
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0answers
29 views
How to measure the peak startup current for an electric motor?
How would I measure the startup current for an electric motor?
For greater context, see https://diy.stackexchange.com/questions/194224/what-kind-of-inverter-do-i-need-for-an-inductive-load/194227?...
0
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1answer
39 views
Current Monitoring circuit setup and option exploration for IoT device testing
I would like to use the ADA4528 opamp or similar opamp to monitor current consumption across a sense resistor for an IoT device but with a Caveat. I want to measure the entire range with one setup/...
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0answers
24 views
What design considerations need to be made to accurately measure current flowing through a BLDC motor due to a 20khz PWM control?
My early attempts to incorporate current sensing onboard a BLDC motor drive operating at 20khz involved the MAX40201FAUA differential amplifier (50V/V) IC and a 0.001ohm shunt resistor. Results were, ...
3
votes
1answer
125 views
Value of resistor and the current in branch with the capacitor
I am trying to learn electronics basics. I have a question asking for the current in the capacitor branch and the value of the resistor that is before the ground
I have used a circuit simulation ...
3
votes
2answers
86 views
What is the result of deviating from the Kelvin layout when designing a current sensing PCB?
For a two terminal current sensing shunt resistor with a layout that deviates from the symmetric Kelvin layout, what results should be expected?
For example, with this layout, what result would be ...
1
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1answer
132 views
Current sense op-amp with integrated shunt vs expensive resistor
To simplify my question lets assume:
I need to convert +/-7.07A RMS AC current into +/-707mV RMS voltage with high acurracy (0.1% or better).
It may be also higher voltage, up to +/-2.5Vpk.
For now ...
0
votes
1answer
37 views
How is the current measured in this setup?
I came across this article where they measure the current called leakage current, but they are not using an ammeter or DMM.
I couldn't understand what(which device) they use to measure the current. ...
0
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0answers
22 views
LED driver - current monitoring AC or DC side with Arduino
I have 2 LED strips connected in parallel to the same LED driver (driver is constant current + constant voltage). I have got an Arduino controlling a relay module that switches the lights on or off (...
0
votes
3answers
52 views
How does the input voltage affect the current consumption of a microcontroller?
Is there a relationship between the current used by a microcontroller unit (MCU) and its input voltage?
In other words, given a MCU with a wide-input range (e.g. 2.7 to 5.5V for the ATmega328P), will ...
0
votes
1answer
65 views
Current Sense Amplifier Potentials
I'm trying to implement a current sense amplifier in my application, but I have a question about setting it up with regards to current flow.
Basically, in this case, you put a very small shunt ...
1
vote
1answer
34 views
Why is ngspice showing current as negative?
I have an extremely simple comparator circuit:
The voltage at pin 7 goes into positive saturation when a positive input voltage is presented at pin 5.
I'm simulating this using SPICE in KiCad. ...
0
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0answers
33 views
High side sensing of pulse current
I try to make high side current sensing from discrete parts (for understanding, this no commercial solution nor student project, just home stuff) for PWM motor driver (buck converter without LC filter)...
