Questions tagged [current-measurement]
Measurements of the current flowing through a circuit
897
questions
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24 views
Hall effect current sensor and proximity to EMI
I am preparing to layout a PCB. I have an ACS723, that I want to use to sense the current going through a relay. In addition to the relay I have a Meanwell IRM-12-20 to supply ac to dc voltage to the ...
-2
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0answers
38 views
Internal resistance of an analog ammeter [closed]
Why does the internal resistance of an analog ammeter decrease as the range used increases? For example say I am using the 100 mA range of a ammeter, if I measure the internal resistance, it is a ...
0
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0answers
23 views
How to calculate Current Emitter (Ie) using Eber-Molls model on an NPN transistor
my computer science professor gave us a problem to code in python involving Ebers-Moll model for circuits where he asks us to find the current emitter (Ie). In the program we ask the user to give us ...
2
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1answer
58 views
Measuring small currents at DC high voltages without floating meter
I'm doing a project with a Cockcroft-Walton multiplier that will output up to 40 kV DC at up to 10 mA. The the circuit takes an input of 10 kV AC at 60 mA and 60 Hz (from a neon sign transformer) and ...
0
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1answer
36 views
Slight drop in voltage regulator circuit
Below is a voltage regulator circuit for which I measured Vo and Io over a range of load resistance values. Why is there a slight drop in Vo when Io is increased, does it have something to do with the ...
0
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1answer
20 views
How to properly place AC current transducer sensor in the circuit
Hello i am going to setup current sensor like this (datasheet) in my home, and would like to know where is it proper to put these sensors in the circuit.
Consider the two setup below:
rent ...
1
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2answers
47 views
touch sensor for metal door handle
I was thinking if a current is applied to a metal door handled and somebody touched it that should complete the circuit to ground and be detectable but I'm not sure if this would work as the 'somebody'...
0
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1answer
51 views
Current induced on a transmisison line
I have a micro-strip transmission line as shown in the figure which is incident by an external EM field. This field will induce some voltage and current on it. I want to measure the induced voltage ...
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2answers
97 views
How to read the position of the decimal point with this multimeter?
I rarely use my multimeter in current mode (I usually it in voltage mode), but here I did a measurement:
I understand that the current is probably 220 mA (thus 0.22...
0
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1answer
31 views
How to prototype current sense circuit on bread board?
Connectors on a breadboard have some resistance, when prototyping a current sense circuit with a 0.01 ohm resistor can the connectors resistance affect the circuit? and if yes how can we prototype ...
0
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2answers
50 views
Inconsistent results measuring current
I am trying to make a datalogger with an Arduino, that should measure the voltage and current comming out of a small solar panel. When I measure the voltage and current using a multimeter, I get a ...
6
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5answers
931 views
Can I measure torque accurately by an electrical or electronic method?
I am a Btech. student from India. We have been given a project in which we have to design a micro-torsion testing device.
We are planning to clamp the specimen and rotate one end by fixed angles ...
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0answers
48 views
Solar Panel not producing current
I am a total electronics noob trying to start out, so I purchased a small solar panel, of 110x80 mm, of 5V and 200mA.
However, when I tried it this morning and connected it to my multimeter, I only ...
0
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2answers
33 views
Is it good using INA213 to amplify +/- 33mV to range 0 -> 3.3V?
I need measure AC current range 0 - 25A using current transformer and burden resistor, voltage swing from -33mV to +33mV. I searched and found INA213 (datasheet). Can I use 3.3V power supply to INA312 ...
6
votes
1answer
122 views
Voltage Controlled Current Source - help needed
I am designing a voltage controlled current generator for the currents in a range from 0 - 2.5mA. The load resistance is within the range of 0 - 5k Ohms.
I decided to go with difference amplifier ...
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1answer
43 views
Measuring Current by rectifying or voltage-doubling a Current Transformer
Originally, my plan was to just get the voltage output of a current transformer (obviously with the burden resistor circuit stuff and DC biasing circuit stuff) before ADC'ing it, averaging it’s output ...
5
votes
6answers
186 views
+100
Measuring the activation time of a solenoid
I'm trying to measure the activation time of a pull-type solenoid.
When the solenoid doesn't have a load connected to it, you can measure its activation time through the current it consumes.
At first,...
0
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0answers
37 views
2 mesh circuit giving me trouble. (steady-stade, mesh current method, dependent current source)
The task is to find Ic in phasor form.
The circuit is in steady sinusoidal state.
I used mesh current analysis and I got to that:
I have no idea how to keep ...
-2
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1answer
68 views
What is the formula for calculating the no load current of a 3-phase motor? [closed]
I am looking for the formula, not a rule of thumb. Is there a way to calculate the no-load current?
0
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2answers
28 views
How to connect multiple sensors to single PLC input?
Hello. I have a scenario where I have multiple PNP "error signal" from several sensors (let's assume 3 for now). If the sensor output is HIGH, then there is error. If the sensor output is LOW, then ...
0
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1answer
40 views
Current transducer - understanding of turns ratio connection
I'm using a LEM LAH 25-NP current sensor and I don't understand the recommended PCB connections in the table from the datasheet. I understand the first one, but what is with the second and third? What ...
4
votes
0answers
141 views
Why does the IC not respond (INA200)
The questions I have:
Is the makeshift IC I use in the simulation a fair representation of the INA200?
I assembled the circuit as shown in the picture (except for the current source and the LED) and ...
0
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2answers
138 views
Why does the measured current differ from the calculated current in this circuit?
I have the following schematic:
Now I want to know the (more or less) exact current flow in my circuit. For this I did the following calculations:
I = V / R
I = 5V / 330 Ohm
I = 0.015A = 15mA
So ...
0
votes
1answer
42 views
Is that any best way to measure High side mosfet drain current?
To be specific, I am using 6 MosFETs (for ex. PSMN030-60YS) to drive an inductive load. I want to measure drain current of High-Side MosFETs. The way I am doing right now is by lifting the MosFET ...
0
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2answers
70 views
Electric current in mic
For a typical mic a singer uses in a concert, how much current is generated when the singer sings? The current transmitted from the diaphragm into the wire.
What does the following specification tell ...
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3answers
83 views
Can I make a ammeter using a voltmeter and ohmmeter that would work in parallel to the device?
I had this small question today when working with an ammeter. Since an ammeter must be in series of the circuit, I had to constantly break the circuit to take current readings. Whereas, when using the ...
2
votes
1answer
51 views
How to measure current to detect motor stall on H-Bridge driven motor?
I have DC motor with a gearbox to transforms the rotational movement to linear movement and movie a pin back and forward.
I need to know when the pin reaches the two positions: full back or full ...
0
votes
1answer
40 views
Understanding current transformer dimensioning, winding resistance and load resistance
I am looking at this current transformer.
What I am trying to understand is the following:
Can the burden/load resistor of a current transformer take an arbitrary value? What are the limits?
Does ...
2
votes
0answers
84 views
How to measure currents between 0.1mA and 100mA? [closed]
Summary of question:
I need to measure (using a microcontroller, not via a meter) currents between 0.1mA and 100mA, with a reasonable level of accuracy - say, to within 0.2 of a mA. My power supply ...
0
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2answers
90 views
In measuring relay contact resistance, should I use 4 wire measurement or calculate it using the voltage across the relay and current?
I'm reading mixed things online where a current from a typical ohmmeter is too low to accurately tell us the true resistance of the relay contacts.
I've got a 30V 2.5A power supply, electronic load, ...
3
votes
4answers
360 views
Why not use a diode instead of a resistor for current sense circuits?
We're building a motor-drive circuit using an L6206 dual H-bridge circuit. The bottom side of its H drivers come out of a pin called \$V_{sense}\$, intended to be connected to ground or to a low-side ...
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0answers
18 views
Current Measurement-DC offset present in input channel of Oscilloscope
Hello!
I am working with two MOSFETs in parallel and I am measuring their turn on currents as shown in picture attached. In the picture, one can see a mismatch between the currents (channel 2 current ...
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1answer
70 views
What is the source of noise in this current measurement?
I'm measuring the current through a 100W motor with a 50A current sensor and I'm getting reasonably good data but there's also a fair amount of noise:
This is the current sensor I'm using. It ...
0
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3answers
83 views
INA168 vs INA169 High-side current sensing
I have read the datasheets of the INA168 and the INA169 and can't see any difference, other than internal resistors value and quiscent current (25uA for INA168, 60uA for INA169). Those two were even ...
0
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1answer
96 views
Where did I miscalculate ohms law in my experiment?
I thought I finally had a grasp on how ohm's law works but when I set up an actual experiment, the numbers don't match up.
To keep a long story short, I converted a computer power supply into a lab ...
0
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0answers
110 views
ZMPT107 + Transimpedance Amplifier + Opamp voltage divider: is this circuit work?
First Sorry my basic knowledge about electric and also English. And sorry title of question is not clear enough. Please correct me if I wrong, Thanks so much
I'm trying design my own household energy ...
0
votes
1answer
53 views
Analog input like in a PLC: Thermistor or 0-10V
Depending on the configuration, PLCs can often measure 0-10V, resistance or 0-20mA on the same set of screws.
How to use the same screw terminal to measure resistance of an NTC element, voltages in ...
2
votes
1answer
62 views
Current monitor circuit not working
For part of a project, I am needing to monitor the current draw of 4 low power loads simultaneously. I like experimenting with circuits and I found one online in a TI application note (AN-31 page 35) ...
0
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1answer
101 views
High side current sensing
I want to sense 30 amps of current using op amp in high side. I know that there are many dedicated current sensing amplifiers for this purpose. But I'd like to try it with an op amp. I have tried high ...
0
votes
1answer
54 views
Measurement of current with hall effect sensor
I have a setup using 3 hall effect current sensors and my goal is to measure the DC current flowing through cables. The sensors are HSTS016L.
I attached a picture of the manual. The sensors have 4 ...
0
votes
1answer
84 views
When I checking the hot terminal in the socket, multimeter shows the current through me?
I set my multimeter in AC voltage measurement, connected + wire of multimeter to the hot terminal of the electrical socket, and take - wire in my hand. Now it measures the voltage. This procedure ...
0
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2answers
101 views
Measure volt, amps, watt and kWh of an external 12 V DC system
I saw online some cheap hardware ~10$ that can measure volt, amps, watt and kWh and display the results on an LCD screen.
I could buy and plug these on my 12 V solar panel system to monitor it. (5 of ...
0
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2answers
56 views
Pulsed DC current measurement using arduino and shunt resistor
I am currently working on a project ( to develop a constant current pulsed DC supply)
in which current has to be measured using Arduino's analog input (Upto 20A) passing through a variable resistance ...
1
vote
1answer
48 views
AC current measure using CT, 10-bit 200 ksps (mcp3008) or 12-bit 100 ksps (mcp3208), which is better?
First, sorry for my bad English
I try to build my own wifi energy metter using esp8266 and mcp3208. My electric knowledge is very simple, now my design use mcp3208 to measure AC current from CT, but ...
2
votes
3answers
122 views
Clamp multimeter RMS current measurement, AC versus DC confusion
This question doesn't relate to a specific meter, I am using AMPROBE AMP-220 manufactured by Beha-Amprobe. I believe am an experienced engineer but only in the digital world, not really in power and ...
0
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0answers
52 views
ST VNH7070 current sense specification
I don't understand the way ST specifies their current sense pin in the VNH7070 H-bridge motor driver, see the datasheet below.
How do I know what the current Isense will be? Why does the voltage ...
0
votes
1answer
27 views
What is the predictable difference of the voltage drop between the V+ and V- lines on a shunt resistor?
I am making an electronic speed controller, and the half-bridge driver I am using has a built-in overcurrent protection feature. In order to utilize this feature, I have to supply the pin (a ...
1
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3answers
193 views
Current measurement with shunt
I need to measure pretty high currents (maximum 100A) flowing from one battery to another. I came up with a solution involving the measurement of the voltage drop across a shunt resistor. The supply I'...
1
vote
1answer
32 views
What's the easiest way to implement portable current measurement for a ~200W dc motor?
I'm tinkering with an electronic skateboard build and I'm looking for a way to do some current measurements "on-the-go". What's the easiest way to implement this?
It wouldn't be a part of the final ...
5
votes
4answers
216 views
Understanding “Current Draw” in terms of “Ohm's Law”
I'm having trouble understanding Current Draw as it relates to Ohm's Law (V = IR).
I have a power supply rated at 5V and 500mA. I'm trying to power a string of LED lights. According to my ...
