Measurements of the current flowing through a circuit

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How do I sense the current from servo motor

I'm doing a project based on a servo motor in which I'm using verilog code. I'm loading that code into an fpga and running a motor. I want to sense the current used at the servo motor and want to give ...
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0answers
50 views

AC electronic load (current sink) (Automatic test equipment for DC/AC)

I am contracting a automatic test equipment for DC/AC converter (24V-5A to 50V/2A). The core of the tester is the electronic load. The electronic load is a constant current sink as the circuit here. ...
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4answers
1k views

Is current flowing backwards a bad thing?

In the circuit below: I find it awkward that the direction of the current on the 2V power supply is running opposite to the direction of the current on the 5V power supply. In the 5V power supply ...
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1answer
69 views

measuring microampere current without noise

I have a constant current source that can output current in the range of 0mA to 1mA. I am driving 100 microamps through a load resistance (1.5Kohm) and then connected another test resistor (1.0 Kohm) ...
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1answer
77 views

Can I measure inductor current by adding a secondary winding?

I have a buck converter and I want to add a current loop to it. I don't want to use a hall-effect sensor or something expensive like that. I think it is not practical to use a sensing resistor since ...
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1answer
49 views

Problems amplifying mV potential differences

I am trying to help my daughter with her science fair project of measuring efficiency of different types of household lighting in various heating conditions. Since she doesn't have the electronics ...
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5answers
74 views

Why does ammeter or voltmeter measures RMS value

When there's an alternative voltage, why does the voltmeter measures rms value instead of the value at that specific time?
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2answers
57 views

Current transformer not sensing currents

I have made a current sense transformer to sense primary current maximum 2A(of my electric iron) and secondary output is 1A but there is no current in the secondary. I have used a iron "Nut" as a ...
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3answers
119 views

How to measure nano-amps easily?

I want to measure the stand-by current of the PIC, but my DVM has minimum 2000micro (u) amper switch. It shows 0 micro amps when in 2000 u amps mode. Without building circuit a complex (more than 3-4 ...
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34 views

Discarding Current Monitor of Linear's LT3482

I've been looking at the LT3482 IC with an APD/Photon Counter application in mind. I need to bias my APD at something like ~65V to reach Geiger mode. Since I've already have a non-inverting ...
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3answers
200 views

Current Divider Formula Proof

Just recently, I was watching a video where the presenter used a current divider formula (I think he called it the "G" rule) to calculate the current flowing throw a resistor on a circuit with two ...
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1answer
61 views

how to calculate the current in this circuit ( opamp)

how to calculate the current in this circuit (show with the green arrow) Can someone explain with a bit of details. In the books i got from school, they dont come close to what this looks like.
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1answer
44 views

can an ammeter damage zeners

So I got this small circuit that plugs to the mains as power source. as for its DC converter, it's one of those transformer-less ones that drops the voltage with a resistors and filters before ...
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3answers
127 views

Wheatstone bridge why not use a voltmeter?

I have been reading up on the limitations of a Wheatstone bridge, one of which is that for high bridge resistances any imbalances are hard to detect because of the small current that flows through the ...
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4answers
493 views

Using two 14 AWG wires instead of one 12 AWG

I do understand there are many factors when choosing what AWG wire, however by the charts, tools, and info I have found, using two 14 AWG copper wires should be equal to a single 8 AWG wire. 8.025 AWG ...
6
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3answers
260 views

Ammeter time limits - how to understand them [duplicate]

On my multimeter, near the 10 A connector it says 10 A MAX 10sec EACH 15min. I usually measure currents less than 1 A so I never cared about this. Is it correct ...
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1answer
73 views

How can I measure the current drawn by a soil hygrometer?

I have one of these ubiquitous soil moisture sensors: The only information I can find is that it operates from 3.3V to 5V, uses an LM393 to trigger a digital output and also exposes an analogue ...
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1answer
120 views

How do I detect servo stall with an Arduino?

I am controlling a standard 5-volt servo with an Arduino with PWM. My objective is to rotate the servo until it physically gets stalled (feels resistance) and then stop. Then I want the Arduino to ...
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2answers
83 views

How to detect current imbalance?

I would like a circuit that detects current imbalance between two conductors. The currents are normally equal and opposite in direction, but can vary in time (or reverse direction). Neither ...
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1answer
49 views

CCVS (current controlled voltage source) in practice

In my current project I'll possibly need to deploy a CCVS (Current controlled voltage source). It is transconductance amplifier or converter and many manufacturers offers transconductance amplifier ...
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2answers
82 views

Why are null measuring methods considered to be very precise?

I heard a professor saying "it's a null method, so it is very precise". He was talking about the force balance pressure measuring method. I think in this cathegory of methods one can include the ...
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2answers
242 views

How to sense current with OPAMP?

I want to sense the current that battery supplies to the low current (few mA) circuit. As everyone said before, forcing discrete design does not make sense, so I decided to apply simple OPAMP & ...
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1answer
83 views

Current Sensing with ACS712 on Beaglebone Black

I am planning to use my BBB to perform some current sensing and was wanting to use the ACS712 chip. The chip operates off of 5V, but the analog inputs of the BBB have a max of 1.8V. How can I wire ...
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1answer
48 views

Understanding High Side Current Sense OpAmp Datasheet

I'm considering the INA199A3, AD8293G80 or TS1102-100 (decreasing cost order) for a high-side current sensing application. According to my understanding the output voltage error is mainly affected by ...
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1answer
42 views

Si8519 AC Current Sensor usage

I'm trying to find a good and practical current sensor and I found this: Si8519 http://www.silabs.com/Support%20Documents/TechnicalDocs/Si85xx.pdf My idea is monitor AC Mains current, so this Si8519 ...
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2answers
94 views

Measuring Electron Beam Currents

When it comes to measuring electron beam currents with a Faraday Cup (or any that will pick up electrons and act as an anode), primarily AC and transient signals, my understanding is that one can (1) ...
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0answers
137 views

Reduce analog reading noise on arduino

With refer to this question: I got CTs connected to all analog pins on a Arduino Mega, connections for each pins are as mentioned here. Readings were good indoors, +- 0.1A. However, when located ...
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3answers
103 views

How is a transconductance amplifier used to measure current?

In this post Design for a Precision LCR Meter the author says: Current is measured via a transconductance amplifier (again with programmable gain) which produces a voltage proportional to the ...
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1answer
88 views

Current sensor with instrumentation amplifier (LT1167)

Objective I'm trying to make a current sensor that can accurately measure current up to 5A. In order to do this I'm using an instrumentation amplifier (LT1167) to measure the voltage difference ...
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2answers
123 views

How do I design a current transformer?

I want to make a Current transformer using toroidal ferrites to measure 220/50-60Hz AC current(40A max). Is it possible? And how can I calculate secondary turns count? Ferrite properties: H = 2000, ...
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2answers
160 views

How much current does a typical multimeter draw to measure resistance?

Assuming it's running on a 9V battery like most multimeters are, and the setting is on MegaOhms. How much current will be drawn from the internal battery?
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2answers
91 views

Series RLC measurement result different with theory

I am measuring the current and voltage in simple RLC circuit: However,the result that I measured show big difference with the simulation result using Multisim. Why is there are a big difference ...
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1answer
52 views

Calculate Current [closed]

how to i calculate current( Before Resistance ) from these parameters Voltage before Resistance Voltage after resistance Resistor Value Current After Resistance
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1answer
337 views

What causes inaccuracy over time on a DMM?

Here is a piece of information from a datasheet of a DMM. The accuracy rates seemed interesting for me. I wonder what causes difference in the accuracy, especially the changes after 24 hrs? Is it only ...
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1answer
328 views

How much power does a wireless mouse use? [closed]

I have seen many answers online to how much power the USB dongle linked to a wireless mouse uses, but nothing about how much power the actual mouse draws from its batteries. What is a ball-park ...
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0answers
117 views

Voltage/current Monitoring - MAX4172 + ADC vs. INA219

I'd like to add some monitoring of voltage and current on the +5V and +3.3V supply rails of a development board power supply. I'm currently debating between two approaches. The first approach is to ...
2
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4answers
935 views

Current sensor measuring circuit

I am planning to design Rshunt basis current measuring. My current measuring range is 1A~2A. I need analog output of 0~5V analog with 1% accuracy. How can I do this? I found conversion circuit here. ...
0
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1answer
103 views

milliwatt-hour meter [closed]

I am looking for a way to design something that can tell me the cumulative power draw of a circuit -- the same concept as a Kill-a-Watt, but measuring mWh rather than KWh. An added bonus would be the ...
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1answer
59 views

How do I place a long wire to make the EMI and inductance minimum?

I'm going to measure high current. After seeing that there is not a lot of low valued sensor resistors in the market and the available ones are very expensive, I decided to make my own current sensing ...
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5answers
192 views

ADC implementation

I want to sense the voltage across the resistor R1 (i.e convert it into digital form). I only have comparators available with me and no other hardware (ADC is not available). Is there any way I ...
0
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1answer
84 views

measuring current to 100uA accuracy in a battery powered circuit

I'm trying to figure out the best way to measure and log current consumption in my circuit, which houses an ATMega2560 and a number of sensors and servos. Using a DMM, I see about 100mA draw when ...
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2answers
143 views

Known voltage/current source

I am working on an EVM for an electricity meter. Its manual says the EVM requires a known voltage and current source for the calibration. I bought a power supply and measure the output of the PSU by ...
2
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2answers
85 views

Inductors in series with different currents

I'm having trouble finding the differential equation that describes the circuit, at t=0 10A flow through L1 and 0A through L2, since current can't change instantaneously. But they're in series so ...
2
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3answers
577 views

How much current is a powered-down ATtiny84 supposed to take?

I know this sounds like a stupid question, but I'm wondering if the datasheet has an error or something. I have an ATtiny84 connected to my bench power supply set for 3 volts. It's fused for the ...
0
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1answer
63 views

Three phase motor current verification

I want to verify that the quadrature current through a permanent magnet synchronous motor (PMSM) is actually the same amount as I commanded the field-oriented control (FOC) motor controller to push it ...
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4answers
251 views

How do I average a complex waveform?

I am trying to figure out how long my project will last on a single battery. It's powered by a single AA battery with an NCP1402 3.3 volt boost converter. I've determined that the target circuit draws ...
2
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2answers
417 views

Solar power monitoring with Raspberry Pi

I want to measure the current and voltage from a set of small solar panels (about 10V and 100mA but not settled yet) using a Raspberry Pi. There will be between 4 and 6 panels. This project will ...
0
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0answers
143 views

How to measure the peak current (inrush current) and results assessment

I would like to peak the inrush current of a controller. The voltage input of the system is 24V and the only thing which is available, is an oscilloscope and a variety of resistors. The basic idea is ...
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4answers
185 views

Is it possible to power AVR micro project with just one coin cell battery?

My current project setup is: ATmega328P micro with 32 LEDS driven by 4 8-bit shift registers. System without LEDs draws 20mA of current continuously. With all LEDs lit at the same time, it draws ...
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0answers
95 views

DC shunt current measuring

I am trying to build DC shunt based high current measuring using bus bar. Each bus bar has a 1000V 20A rating. Is any IC available to measure? I have done with hall sensor based. So my plan to build ...