# Questions tagged [current-measurement]

Measurements of the current flowing through a circuit

1,532 questions
Filter by
Sorted by
Tagged with
1 vote
40 views

### Distribute power from one battery to multiple devices

I have a battery, Li-po 3300mAh 22.2V 60C. Then, I have a system (main system, so to speak) which consist of STM32MP1 MPU (operating voltage [1.71, 3.6], typ. 3.3), STA8135GA GNSS IC (operating ...
• 13
26 views

### “Opentherm” interface. Power design of a thermostat

I'm trying to understand OPENTHERM protocol (by its hardware part). In a couple of words opentherm is a 2-wire interface used between thermostat and boiler. The data from thermostat (master) to the ...
166 views

### How do I create a circuit to reliably calculate a range of unknown resistances?

I'm designing a low power circuit which serves to determine the unknown resistance across a 16 channel sensor. So far the results are bit subpar. The resistances are a function of a different applied ...
• 113
1 vote
84 views

### How to sample current in high-kHz to low-MHz [closed]

I am working on a project that, at its simplest, is a switching circuit (either a half-bridge or single switch) connected to a resonant filter. I need a way to measure/sample the current going from ...
26 views

### Brown outs with Nordic Instruments PPK2 power profiler

I have a circuit that I know works with 2 AA batteries that are nearly dead (1.4 volts total). I want to measure the current consumption of the circuit using my Nordic Instruments PPK2 meter. The only ...
• 193
49 views

### What does an accuracy of 0.1% + 20 mV mean in a power analyzer's data sheet?

I need to know the measurement accuracy of Keysight N6705C power analyzer. I came across this document (N6700 Modular Power System Family.pdf) that states the error in terms of a percentage plus a ...
• 215
1 vote
42 views

### Combining a differential amp and current limiting circuit

I've been experimenting with a very simple current limiter that regulates the current through a solenoid with a 3-4 ohm resistance. The external driving circuit is a PWM switched N-Ch MOSFET ...
• 1,341
58 views

### Battery draining and resistor question [closed]

Say I have a motor that uses 9v @400ma, but it's powered by a 12v battery. I 'd use the ohm law and get a: 7.5 ohm resistor. But, as soon as the battery is being drained, let's say now the battery is ...
53 views

I'm trying to read current with INA186 on low-side. The shunt resistor calculations are ok, but the current sensed, comes from a pulse DC signal of a SCR. This SCR is rectifying the output of a power ...
1 vote
48 views

### What happens when the value of resistances used in a differential input filter for a current sense amplifier circuit is too small?

I am working on a current sense amplifier circuit with the following configuration: While the circuit works, the filter is not performing as intended. Specifically, it should act as a low-pass filter ...
• 41
43 views

### Sinking and sourcing current from and to the output of the op-amp

I need to have a set-up to sink and source current from the output of an op-amp to measure the maximum output current of an op-amp. This is the test set-up I thought of: If the maximum output swing is ...
51 views

### high voltage moderate frequency galvanically isolated current measurement

Given a conductor carrying a sawtooth wave of anywhere between 0.1Hz and 855kHz up to +-1.5kV) and anywhere between +-(1µA...20A)(maximum 650W) i want to measure the current with about 5MS/s (so the ...
44 views

### Ignoring current spikes

I have a circuit which measures a current draw going to System A, waits for it to rise from 0.24A to 0.26A, then has a 30s delay before supplying power to System B. If the current drops below the ...
• 985
54 views

### current transducer Burden Resistor configurations

How will the current flow? Will it go from x1 to gnd and x2 to gnd---(Rb=30ohms) or x1 to x2 and x2 to x1 (Rb=60ohms) and when no current is flowing r1 and r2 will act as an pull-down resistor so ...
16 views

### Power indicator circuit with overcurrent signaling

I'm seeking advice on a circuit I've developed through experimentation, patience, and determination. While I have a technical education in electronics and electric systems from middle school, I'm not ...
1k views

### How can I make this AC current switch turn on at 20mA instead of 50mA?

I've bought this AC current switch, which is sensitive to currents from 50 mA to 5 A on the single AC wire that passes inside its hole. When currents from 50 mA start to flow in the wire, it allows ...
• 567
1 vote
22 views

### Cost and space effective isolated sensor for low ac currents

I am working on a product where I need to measure small ac current (around 2 mA). The image below shows the wiring: There is a power supply that powers up a variable power load (this is user ...
• 8,316
1k views

### Measuring the resistance of an LED -> getting conflicting values

I couldn't find the resistance values for an LED so I tried to measure it and ended up much more confused than before: I have a plain (red) LED and initially I used a multimeter to measure the ...
1k views

### How do I tell if a shunt resistor is routed using the Kelvin method?

I am struggling to get my head around Kelvin PCB routing for shunt resistors. First how do I tell if a shunt resistor on a PCB is routed using the Kelvin method? Below are three images: THE TWO RED ...
• 2,389
816 views

### Measuring nA leakage current

I'm trying to measure some leakage currents of both a diode (expected around 5 nA) and a MOSFET (20 nA). My issue is my meter's measurement accuracy is only around 10 uA, and I need an accurate ...
65 views

### High current/voltage power monitoring in small form factor

I am attempting to build an I/O board to integrate with software I have running on a Raspberry Pi 4. I need the board to monitor voltage and current (power would be a bonus) on 8 circuits running ...
• 131
80 views

### Getting different answers for number of electrons in 1 amp? [duplicate]

I was looking up the number of electrons in a current with 1a and I keep on getting different answers. Some websites put the number at 6.24, some at 6.25 and others at 6.28 (all * 10^18) Is there some ...
82 views

### How can a current probe avoid saturation?

It is a buck converter, And I want to know how current probe can avoid saturation. Turns ratio is 1:1000. And DC makes transformer saturation. So... How can probe avoid saturation?
1 vote
106 views

### Microcontroller that can do 10 UART? [closed]

I am currently working on a project that would require a total of 10 UART (rx and tx pins) to run 10 PZEM-004Ts for different electrical lines. I am thinking of using an atmega 2560 because it has ...
• 11
1 vote
115 views

### Whats the meaning of Im, Is and Ih

I would like to know what's the meaning for the abbreviations of Im, Is and Ih in leakage currents measurements, as it is depicted in these graphis. Could anyone help me?. The link of the source is: ...
95 views

### measuring microamps Arduino/esp32

I have an analogue gauge that works off a 0 to 1mA input. The gauge is for a fuel tank on a ship. Given the input current is 1 mA at the most, what can I do to make this readable on an esp32? I tried ...
• 3
211 views

### LTspice Meas Directive?

I need some help with LTspice MEAS directive. I have a simple circuit, a DC power supply, and a variable Load resistor to observe the current limiter behavior. I made the variable load resistor and ...
• 643
684 views

### Measure very small current with Arduino? [closed]

I have to make a circuit/device in which i have to measure very small current in a wire carrying ac current. In a given scenario, there will be a live wire carrying as low as 0.2A and as high as 100A. ...
• 222
47 views

### Scalable Voltage Display

I am trying to create my first PCB, and I am trying to measure and display scaled voltage and current output from a few different sensors on several seven segment displays. For example, one of the ...
1 vote
70 views

### Piezoelectric Disk Charge Generation and Detection

I have a piezoelectric disk. I am trying to determine the sensitivity of this disk for the sake of making a charge model more accurate. The charge model in question: I have attached the piezoelectric ...
• 913
1k views

### How to design a circuit to measure really small currents (nanoamperes for example)?

I have to design an analog circuit to measure currents in the nano ampere range as part of a course, and from what I found on Wikipedia and some documentation available online from Tektronix, it seems ...
140 views

### If I connect 3 12V batteries in parallel to eachother, then connect them to the load, am I connecting to the Load in parallel or series?

I have 3 12V batteries. I have connected the 12V batteries in parallel to each other. I have 1 positive lead and 1 negative lead coming off to my motor. Am I connecting to that motor in parallel or in ...
• 1
1 vote
33 views

### PSC motor auxiliary winding current at full speed

In articles, e.g. here, I often find this statement: In an auxiliary winding, a counter EMF is produced as the speed of the motor increases, and this EMF will limit the current that passes through ...
62 views

### Determining load voltage and current of a pump connected to long wires

I'm trying to estimate the load voltage and current of a pump connected to a power supply with long wires. Here is a schematic: simulate this circuit – Schematic created using CircuitLab The ...
• 21
75 views

### Measure transformer real power

I’m new at making transformers myself, and the ones that I designed had the correct output voltage, and when they were connected to batteries (previously rectified), they give me a an approximate of ...
64 views

### What type of galvanometer is in this picture?

Does anyone understand the galvanometer in Faraday's experiment to the left in the picture below? How does it operate? It looks like it uses a magnet and some xy axis the needle swings over or maybe ...
• 383
135 views

### Test circuit for a solar panel used to power a supercapacitor

I was hoping to power a device with a supercapacitor that would provide power when there isn't light available, so essentially I just need the solar cell to charge the supercap as fast as it would ...
66 views

### Current transducer: no voltage

I am working on a project that requires non-contact current measurement. I found the LEM LA 25-P active current transducer. I've put the connection diagram from the datasheet here. My understanding is ...
80 views

### Allegro ACS37002 - Noise Issue

I have a noise issue with the Allegro ACS37002LLAATR-015B3 (+-10A), where I see HF noise in the VIOUT signal of about +-50mV at no load attached to the sensor, which would be equivalent of around +-...
• 1,038
52 views

### Large current flow through SMD shunt resistor

What is the best way to large current flow through SMD resistor? As you know, latest FPGA like ULTRA series or Versal series need large Core current almost over the hundred ampere. It is not problem, ...
• 15
2k views

### Why do different multimeters give me very different current measurements?

I was trying to calculate R_TH using an open-circuit voltage and a short-circuit current, and I am having trouble with the current measurement. I noticed that my calculated R_TH didn’t match my ...
1 vote
45 views

### Do we have to share the ground between a load and a sense-resistor based current meter?

I see in the datasheets of some current-meter chips, that the LOAD ground is also the same as current-meter chip (inAMP for example) ground. For example AD8293 inAMP: Or this model (INA3221) from ti: ...
• 2,013
65 views

### Uncertainty for measuring a resistor

I am trying to calculate the uncertainty of a measure on a resistor. The expected value of the resistor is 45 mΩ. For measuring the resistor I used the two following instruments: SM500-CP-90 Agilent ...
• 2,444
43 views

### Current sensor output impedance information

I am using ZXCT1084QE5TA high-side current sensor, upon inspecting datasheet I came across this very weird output impedance information, which I don't really understand. There are two versions of ...
• 433
94 views

### Why do treadmill amperages fluctuate? [closed]

Multiple sources describe monitoring a treadmill’s current as an indicator of friction. When it increases, it’s time to add silicone oil between the deck and the undersurface of the belt. One good ...
• 31
39 views

### How can I understand the operation of this scale selector for current measurements on the Power Profiler Kit?

I'm reviewing the design of the Power Profiler Kit II, generously provided by Nordic here, specifically the auto-scale selection stage for measuring current, the first stage being this: I manage to ...
• 440
57 views

### Identify correct voltage/amperes from bulb brightness

Is there a method to establish correct voltage of an incandescent bulb by offering a voltage and measure brightness? In other words, is there a chart that tells you the brightness range of a 2.5V bulb ...
122 views

### Why does this ACS712 current sensor have this voltage output? [closed]

I connected a 250 V, 50 Hz power supply to the ACS712 5A current sensor and set it to 9 V. I would like to know why the voltage output is 6.42 V.
• 57
1 vote