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Questions tagged [current]

Flow of electric charge - typically movement of charge carriers, such as electrons. Measured in amperes (A).

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2answers
30 views

For a bandpass transfer function, are there two gain bandwidth products?

Every example I have come across shows the gain bandwidth product used only for low pass transfer functions, but I never see it used for bandpass or in fact high pass transfer functions. Why is this?
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4answers
722 views

What is the name of this current called in this regulator datasheet?

Which parameter in this data sheet is the default current flowing from the input to the ground regardless of the load current? In my case an 12V input will be regulated to 5V by the TL780-05. So to ...
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0answers
38 views

Is it safe to make common ground between multiple voltage planes

I have a system where I have two power inputs and a single power output. One input from a battery(13v, 10A max) and one from solar cells(19v, 10A max). Then there is an 12v output which I connect to a ...
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1answer
39 views

sensing current noninvasively using hall effect sensors

I am trying to sense if DC current increases in a wire when the load changes. I do not care about the value of the current, I only want to know if it increases (motor at idle vs motor running). I ...
0
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1answer
53 views

Measuring high currents with toroids

I got a PT27312 current sensor (datasheet), I wonder if I can use it to measure currents up to 100A AC/DC. I couldn't find any specifications in respect of the current measurement range. I only know ...
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1answer
36 views

How to calculate current sink

Below schematic is what I have on the breadboard: simulate this circuit – Schematic created using CircuitLab R1 is there to sink 10mA of current to bias LM317, but 470 ohm is a value that I ...
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3answers
92 views

Does current flow across 0 resistance and 0 potential difference?

For the following circuit, will current flow from 3' to 3. I know that both are at 0V. However, the resistance between 3' to 3 is 0 ohms. So, ohms law would give the current as 0/0 which is ...
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2answers
77 views

How does this circuit work (opentherm)?

I am trying to understand how this data interface works. It's supposed to: translate (read) "OT" current difference into logical OUT (<10mA = 0, >17mA = ...
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3answers
740 views

Meaning of “pulse duration” in transistor datasheets?

I have a somewhat basic question. Many transistor datasheets have something like this for the peak current: pulse duration = 300 μs, duty cycle ≤ 1 % What does pulse duration mean? Is it only the on ...
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2answers
62 views

Opamp Current Sink + FET circuit help

I've been trying to figure out a design someone made for controlling a precision high current LED, and it's got me in a bit of a pickle. For the life of me, I can't figure out this exact op amp ...
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1answer
31 views

What is the maximum current can pass in BQ40Z50R2 (fuel gauge IC?)

I am unable to find the maximum current this fuel gauge IC can pass from its datasheet. Can anyone tell me?
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0answers
21 views

What is the current limitation of lenovo c340 USB port? [closed]

How much DC current can I "ask" of the lenovo c340 before it's damaged? Will it cut the supply on its own? at what conditions? what current is the max for a long time and what is the allowed peak?
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1answer
21 views

Inrush current and number of devices per MCB

I'm looking at some LED drivers meant to be powered by the regular mains voltage (230V). The datasheet specifies how many drivers can be connected to a single Miniature Circuit Breaker (MCB) on ...
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3answers
76 views

Current and resistance

Can anybody explain why my tongue gets a reading on a multimeter. Do I have a current? Why do i have resistance? Why do some things have resistance? I am very confused.
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3answers
85 views

Total current current equation in P-N junction

So Okay I get why there is a negative sign in the equation for diffusion current of holes since the gradience is actually negative if we put our coordinate axis in the bottom left corner for example ...
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0answers
52 views

Find current in the s-domain with 12V dc source

Notice my edit below I am trying to find the current i(t) that goes through the inductor in the s-domain. I know that it can be done the following way: $$I(s)=\frac{Y_1(s)}{Y_{eq}(s)}\cdot I(s)$$ ...
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1answer
100 views

Is there a proof of the following statement?

I am reading Electronic Principles by P.E. Gray and C.L. Searle and I came across the following statement. If there are n capacitors and no capacitor loops, the highest power of s in the ...
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6answers
127 views

Will current usage increase with different length of wire? [closed]

Given all other factors are same, with only the wire length increased (for example, 0.5meter increase to 50 meters,) will the current consumption/usage increase as well? Can anyone explain?
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3answers
33 views

Correct way of calculating BLDC torque for a given RPM and Current

A permanent-magnet 3-phase brushless DC electric motor is attached to a load. Motor is operated with vESC6.6 inverter, which is software-limited to 140A. Measured efficiency at maximum power is 81%. ...
0
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1answer
56 views

Current through a transistor

I have a problem related with a transistor circuit. Please tell me whether my approach is correct or not. I need to find the current through the 94.6ohms transistor. My approach (Assuming PN voltage ...
0
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1answer
45 views

Inverted Op Amp for Current Sensor Output

I'm having trouble understanding why the following circuit uses the inverting configuration rather than the non-inverting configuration for amplification. This design is from the Sparkfun Current ...
0
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1answer
37 views

Finding the maximum current

So, we did our lab activity and I don't quite understand the question "How could the circuit be modified so that the maximum current could be set to a value higher than that achieved by the supply ...
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0answers
62 views

using current limiting diodes instead of resistors

Most 3d printers have stepper motors that are rated for maybe 2-3 volts, but are usually driven at much higher voltage like 12 or 24 volts. It's possible since the motor drivers are current limiting - ...
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3answers
103 views

Output stage using 2 transistors

I want to understand how does this 2-transistor circuit work. It is used in a schematic for increasing the current rating at the discrete output stage. This does not look like a standard darlington ...
0
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1answer
24 views

Connecting multiple LED strips in parallel to a 220v/5A power line (via 12V driver)

I would like to power 5 LED strips via a 220v/5A wall outlet (each strip is 5m in length). I will be consulting and employing the electrician for the best way to run the wiring but from the initial ...
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1answer
25 views

Interface conditions and surface current density

let's consider the interface condition for magnetic field strength: 1) I do not have a clear idea of what js represents. If I have understood it correctly, it is a linear density ([A/m]) of a surface ...
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2answers
64 views

How do I find the equivalent circuit of a compensated attenuator?

I can not find the equivalent circuit due to the wire joining the middle of the resistor branch and the capacitor branch.
1
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2answers
88 views

Why is my Transformer pulling so much current?

I have taken a microwave oven transformer and removed the 2nd winding which originally put out 2000 volts. I have rewound the 2nd coil to produce 21 VAC which I then rectify and smooth with 2 large ...
0
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1answer
34 views

How do I solve the input resistance of this BJT and MOSFET in series?

This is a sedra-smith microelectronics excercise question for which I can not find the answer and I hoped for perhaps a solution here?
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0answers
29 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 ...
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1answer
72 views

why the voltage at the gate terminal is 1.8V irrespective of the 3.3V pull up? [closed]

[![the output of my GPIO is 1.8V which is pulled up to 3.3V using a 4.7K resistance and that gpio is connected to the gate terminal of a P-channel mosfet, when i measure voltage across the gate ...
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1answer
41 views

Changeover relay circuit

I am looking for a circuit for one of mine typical application. I have transformer power supply with 230VAC/DC input with 12V /1A and 5V/500mA output. Now I wanted to introduce another stand by power ...
2
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2answers
64 views

Phase difference between resistor and inductor voltage in an RL AC circuit

In my textbook, it is given that \$\mathcal {E} = -L\frac{\Delta I}{\Delta t}\$. The graph of resistor voltage (\$V_R\$) and inductor voltage (\$V_L\$) in a series RL AC circuit is given similar to ...
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0answers
111 views

Is there a derivation of the Early effect?

I can't seem to find a derivation of the following equation: $$I_C=I_Se^{\frac{V_{BE}}{V_{T}}}\left(1+\frac{V_{CE}}{V_A}\right)$$ Is there a way to derive this equation? Edit: The equation ...
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3answers
56 views

amplify/increase current from 9v battery

I have a working circuit that generates a signal (a range of slow and fast tones) and sends them to a speaker. I tried to switch to a piezo driver and speaker and was successful using the MAX9788 as ...
0
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1answer
32 views

Low power rectification of AC component of modulated current signal

I have a current source consisting of a 100Hz sine plus a DC offset: \$I=I_{DC}+I_{AC}\cdot\sin(2\cdot\pi\cdot 100Hz\cdot t)\$ with \$ I_{DC}\approx100uA\$ and \$I_{AC}\approx 1uA\$. I would like to ...
0
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1answer
32 views

Diffusion current causes drift current?

I was studying about currents in an injected semiconductor (by illumination) from Integrated Electronics by Millman and Halkias. They consider the diffusion hole current in an injected n-type open-...
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1answer
80 views

BJT Circuit Current

I have a question regarding the circuit below. I am unsure how to calculate the current flowing through the 1k resistor. I think it is reasonable assumption that the collector of the PNP BJT must ...
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3answers
103 views

Is the electric current delayed

simulate this circuit – Schematic created using CircuitLab -Suppose that the distance between "D1" and "D2" is too large. -Does "D2" give a delayed response compared to "D1"?
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1answer
63 views

Reverse Current building up Voltage

Just wanted to clarify my understanding before I design my circuit. This is based on my previous question I have an 3.3V LDO Regulator. Vin = Regulated 5V Vout = 3.3V Load Current = 100mA. At ...
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0answers
43 views

Why do people waste time using a SPICE .NOISE analysis for circuits with resistances with significant excess noise?

Refer to Resistor Current Noise Measurement Excess noise in a resistor is the electrical noise which is in excess of the value predicted by the well-known Johnsson-Nyquist-Thermal noise formula. ...
0
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1answer
91 views

How can I get/build a current controller/amplifier?

Background: I have a Lorenz-actuator (coil+magnet) that I need to control precisely using a computer. The computer signal is output from a dSpace microLab box as an analog ±10V signal. This signal ...
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2answers
50 views

Switch current rating label: 0.1GPA

I feel like this ought to be a FAQ, but because of the abundance of articles on Grade Point Average coming out of the US, it's extremely difficult to search for. I have a micro switch with rather ...
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2answers
43 views

Choosing a current sensor based on mV per amp

I want to measure AC current with an Arduino-type device. I am currently selecting a current sensor. A 10 bit ADC gives 1023 points. At 5v that is 5v/1023 = 4.9mV A current sensor with 185mV/A thus ...
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0answers
123 views

Transformer Welfare

I know this circuit is dangerous, but i made it anyway (probably a mistake)-https://www.instructables.com/id/Variable-voltage-ignition-coil-power-supply/ In my circuit, I used a small ignition coil ...
4
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2answers
159 views

voltage regulator current draw

I have a question about the operation of a voltage regulator. The supply is 12V and can provide 15W (max current draw 1.25A). Now when I use a linear voltage regulator down to 5V do the 15W still ...
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3answers
58 views

Buck converter source current draw

I'm doing some calculations for a system that is going to use a few buck converters. I need to make sure that the battery will be able to feed enough current but I'm not 100% certain how power on the ...
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2answers
54 views

DC Power Supply maximum current

let's consider a DC power supply of 5V with for instance 1A of maximum output current (i.e. its maximum output power if 5W). Let's connect a load R = 1 Ohm. Ideally a voltage source of 5V will give ...
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2answers
99 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...
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4answers
80 views

Current booster for relay

I have a DC power source which can provide up to 5V, 50mA (LabJack maximum output current, voltage bus-powered) and I want to power my relay (SDT-S-105LMR2,000) with 5V, 100mA. I have an option to use ...