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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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1answer
28 views

Why are two-port networks able to use a dependent source but not an independent source?

A two-port network can be modeled as black box with two-port parameters provided the two-port network consists of no internal independent sources. This restriction does not apply to a two-port ...
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2answers
90 views

Complex Voltage and Current in Steady State DC Circuit with Nonlinear Component

I was trying to solve the following circuit that has a nonlinear component: simulate this circuit – Schematic created using CircuitLab B is the nonlinear component with the following ...
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2answers
60 views

Using a Main Surge Protector for only branching out other surge protectors

Whenever I try to find information about this question it always says that it is not good to plug in a surge protector into a surge protector because you can overload or overheat the protector or ...
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1answer
43 views

What happens when we discharge a capacitor through a SCR which we leave open?

I am wondering what would happen when we discharge a capacitor, by using a SCR, through a coil and we leave a current applied to the gate of the SCR. The coil should generate a ‘reverse’ current right?...
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0answers
30 views

Opto-coupler high vs low CTR

I want to understand how the CTR of an opto-coupler is linked with its other parameters, for example its switching speed or time delay between input and output or any other parameter. I am using ...
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1answer
53 views

Water and electricity? [on hold]

I just put my Ipad Air 3 in my bag, it was raining and forgot to close it such that when I got home, my Ipad and the inside of my bag was extremely wet. I know a bit of physics but not figure whether ...
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0answers
26 views

Current mirror not depending on power supply (BANDGAP design)

is there any topology that allows a current to stay constant on a current mirror when the power supply of the transistor is varied? I simulated a bandgap and the PTAT varies a lot when I the power ...
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2answers
148 views

How to read the position of the decimal point with this multimeter?

Note (edit): This cheap multimeter has a bad serigraphy, confirmed by comments of other buyers. The top range should probably be 200 µA. I rarely use my multimeter in current mode (I usually it in ...
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5answers
1k views

How is a series resistor limiting the voltage for a diode?

I try to understand some basic concepts, but I'm stuck with this question. I have this schematic, with a power supply 9V, a resistor 450ohm and a LED. Assuming the LED consum 16mA, this resistor have ...
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1answer
148 views

How to estimate current consumption by ICs

I'm using an Arduino Due (3.3V) which has a maximum current for all pins 130mA. How to estimate consumption for a number of ICs? For an example i use multiple MCP4822 (2channel DAC) On the ...
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0answers
19 views

Current probe powered down due to Low battery voltage [on hold]

I am using this Current Probe powered by a 9V battery. I found this not powering On. Upon opening and checking the battery voltage, I found it 6.07V. But isn't 6.07V, a good amount of voltage for ...
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2answers
176 views

Battery failing. Oscilloscope?

The question is - is there an inexpensive oscilloscope I can use to measure DC voltage and current to see why my battery pack is failing to power a DSLR? In order to take long time lapse photos with ...
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1answer
32 views

What is the difference between transresistance and differential resistance?

Transresistance is defined as the change in output voltage over change in input current. While differential resistance is defined in the same manner. So what is the difference ?
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0answers
27 views

Why it is okay to charge a fast charging and normal charging phone with same voltage rating, using fast charge adapter

Why it is okay to charge a fast charging and normal charging phone with same voltage rating, using fast charge adapter
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1answer
116 views

Questions from a current regulating and measuring circuit

In my previous question I asked about a simple topology suggestions for regulation of highish currents(around 10A) especially for resistive heating elements in 1...10 Ohm range. I concluded to use a ...
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3answers
102 views

Electric field strength from AC conducting wire in form of a loop along z-axis?

Let's say I want to calculate the electric field strength from an AC conducting wire, with a certain frequency and current. The wire is in the form av a loop. I want to calculate the E-field along the ...
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2answers
252 views

how to determine the current in this circuit

After calculating total resistance and total current, I am applying current division and I obtain (6/6+6)*1A = 1/2 A. But in the answer key it is presented as 1/3 A. What am I doing wrong?
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2answers
33 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
757 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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2answers
3k views

A confusion about the formula for transistor Vbe Ic characterisitcs

Below is NPN BJT transistor Vbe Ic characteristics and the formula: Many texts approximate this equation as: Ic = Is*e^(Vbe/Ut) and following this they say when Vbe=0, Ic becomes equal to Is. ...
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3answers
78 views

Why current appears at reverse bias?

I am simulating time-domain graphs of a Schottky diode model. I am expecting ~zero current at the negative half cycle. But I am seeing negative current. It's only about 3mA, but based on I-V curve, ...
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1answer
269 views

Cannot find “reverse saturation current” of base-emitter junction in the data-sheet

Regarding the reverse saturation current \$I_{ES}\$ aka \$ I_{EO}\$ of an NPN transistor, according to Ebers–Moll Model: \$I_E = I_{ES} (e^{V_{BE}/V_T} -1) -\alpha_RI_{CS}(e^{V_{BC}/V_T}-1)\$ ...
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0answers
42 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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2answers
131 views

Why there is not a sqrt(3) factor between rated currents on the delta-wye transformer?

When calculating the rated current on either side of a delta-wye transformer, we will use the following equation: $$ I_{LL}= \dfrac{S_{3\Phi}}{\sqrt3*V_{LL}} $$ Since this same equation is used for ...
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1answer
183 views

Finding the primary VA when winding your own power transformer?

I have been researching how to build power transformers but I am stuck on finding the proper wire gauge for winding the primary. In order to find the correct wire size I have to know the current in ...
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2answers
64 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
40 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 ...
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votes
3answers
746 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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1answer
99 views

Why does writing to a read-only register increase current consumption?

Looking at the datasheet of the MSP430, it says writing to read-only registers results in increased current consumption. Why is that? What is happening when trying to write to a read-only section of ...
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1answer
54 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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3answers
160 views

How to block reverse current from battery to charger (DC-buck CC/CV module)?

The set-up For a project, I have a set-up where the power to the main load comes from either a AC-DC adapter input (24V) or a battery pack (12V to 16.8V - 4S4P 18650 Li-ion cells). The battery pack ...
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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
315 views

Does cutting LED strips into smaller strips then wiring with low AWG decrease temperature?

As you know SMD LED Strips can get damn hot and I'm looking at easy ways to reduce the temperature so that the LEDS remain bright for longer. It is my understanding that your typical LED strip will ...
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3answers
302 views

Reverse Current Protection using two PMOS in back to back configuration

I am working on a circuit that needs reverse current protection. Back to back mosfet configuration has been suggested by many people, and it seems to make sense at the beginning. But after I built my ...
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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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2answers
78 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 = ...
-4
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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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1answer
33 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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4answers
1k views

Fuse: why does it connect in parrallel with resistor?

I have a wire in normal condition runs 4A. The device I am using is auto-transformer, and its data sheet recommend to use fuse of 10A. So I went to buy the 10A fuse, and mount it onto a fuse holder. ...
0
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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.
0
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1answer
101 views

How do non-flowing common mode or bias currents cause common mode range to exceed/float?

Below is a very simplistic view of differential ended inputs of a data-acquisition channel's inAmp which measures a floating battery voltage V. To make concepts and explanations simpler I use two ...
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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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2answers
120 views

Help with design of current DAC

I am required to design a current DAC (64 element NMOS) that sinks the current of another current DAC (16 element PMOS). The specs are as follows: 1. The smallest current output from the PMOS DAC is ...
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3answers
6k views

6W 12V 5A peltier only drawing 1A, I am supplying more current but its only drawing 1A

I just bought the peltier and its of 60W 12V 5A and its maximum capacity is of 90 watt power. I am using my Pc power supply which have ability to provide 12V and 15A maximum. I connect to that lead ...
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2answers
231 views

What is the maximum charge current and discharge current of R5460 Series IC?

I am using "R5460N214AF" IC for 2 cell Li-Ion battery protection. According to datasheet, excess discharge current threshold is 0.2 V and excess charge current threshold is -0.2 V. I would like to ...
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6answers
129 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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1answer
119 views

Direction of current in a wire connecting two conducting loops placed concentrically in a time varying magnetic field which is into the plane of paper

Figure shown plane figure made of a conductor located in a magnetic field along the inward normal to the plane of the figure. The magnetic field starts increasing. What will be the direction of ...