Questions tagged [current]

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

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1answer
71 views

Sizing capacitor to avoid/supress current spike?

On a rather weak 5 V supply I need to power a circuit requiring around 650 mA in short spikes (20-50 ms). Outside of the spikes the circuit requires about 30 mA. The supply is able to supply sustained ...
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1answer
122 views

Faraday Cage - Wavelength and hole size

I read about the faraday cages and understood that the size of the holes should be very small than the wavelength of the signal for effective shielding. But I am really confused due to the ...
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0answers
68 views

Battery options for 500mA load

I need to energize a load with 500mA current for 10 seconds. Voltage doesn't needs to be constant but can be in between 0.1v to 1v. The application has size constraints so I can only use a button cell ...
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2answers
86 views

For Switching Applications - BJT or MOSFET [duplicate]

I am trying to read and understand on what device would be a better switching element - BJT or MOSFET. From what I have read and my understanding is that: If the application requires faster switching, ...
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3answers
72 views

Current Feedback/Sense Circuit

I am trying to understand the circuit from this datasheet so I can use it in a project. The issue I am having is how the current feedback works (circled below). OUT_IFB is the current feedback for the ...
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2answers
157 views

How does a transformer operate with a short in the windings

I'm trying to learn more about transformers that are failing. From my understanding transformers create heat. From too much load or current on the secondary side of a step-down transformer, the heat ...
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0answers
52 views

Current feedback amplifier

I was wondering whether is it ok to connect a current feedback amplifier (CFA) after the TIA stage to obtain high swing and large bandwidth. I am not sure how to connect the CFA after the TIA stage.
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4answers
486 views

Output capacitors of DC-DC converters

I am trying to understand what type of output capacitor is a better option. Suppose I require a 10uF output capacitor at the output of the buck converter, which one should I pick - aluminum ...
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3answers
154 views

Does a floating load on a transformer have no voltage difference with ground?

I think I know the answer, but I'm unsure. I'm studying for my FE, and in the practice exam is the following question: An ideal transformer connects a 120-V, 60-Hz voltage source to a load. One ...
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1answer
52 views

How does differential mode noise and common mode noise occur

I was reading this article on common mode and differential mode noise. But it is not mentioned anywhere on how the differential mode noise and common mode noise occurs. From the diagram, I kind of ...
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3answers
101 views

If a voltage source is current limited does this actually mean that the voltage across the load is limited?

For the past while I've been struggling to wrap my head around electricity. One thing that has puzzled me to no end is the relationship between current and voltage. On paper it's a really simple ...
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0answers
79 views

Right capacitance for a capacitor parallel over power output?

I am building a self playing piano. I daisy-chained 11 74hc595 shift registers to control (11*8) solenoids. (figure 1 only shows 1). The solenoids are rated at 2 Amps each. I use SPI from the arduino ...
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0answers
41 views

How do I make a battery indicator? [duplicate]

I want to make a battery indicator where there is only one red LED that would light up when the battery drops below a 3V. Components I want to include in this circuit -Transistor(BJT)(2N3904) -Zener ...
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3answers
856 views

I need to power a device that requires 12V and 0.43A, with as small of a battery as possible

Basically, I have a device that MUST be powered by battery and it requires according to the item description an operating voltage of 12V and 0.43 Amperes. There are small batteries (A23 batteries) ...
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1answer
61 views

How to find the minimum and maximum voltage of this buck converter

I am using buck converter. 3.3V output & 2.5A part with 2.1MHz switching frequency. I am powering my microcontroller with this 3.3V output. So, I'd like to find the output voltage tolerance of the ...
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1answer
123 views

LC filter of buck converter

Can someone explain me intuitively on why the LC filter cut off frequency should be very less than the switching frequency of the buck converter? What is the reason and why can't it be higher than the ...
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3answers
98 views

Comparator vs op-amp

I was trying to find the difference between a normal op-amp and a comparator. I saw one video where they mention that an op-amp without feedback is a comparator. I have a few op-amps which have a ...
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1answer
70 views

Buck converter output LC filter phase difference

I was going through a few buck converter questions in this forum to understand deeply about the circuit and I found this question. However, I am not focused too much on the ripple right now. But when ...
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3answers
275 views

Voltage and current [duplicate]

It is proven only when there is a potential difference current flows in that branch between two nodes, then how we say that the current flows in a short circuit where the voltage on that branch is 0?
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2answers
156 views

What causes harmonics in DC-DC Switching converters like Buck and Boost Converter

Can someone tell me what and how the harmonics are caused in the DC-DC Switching converters? I tried to read this, but I am not understanding. Can someone please explain in simple terms
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1answer
51 views

Buck Converter Switching Loop Area in Layout Should be small

I have seen recommendations in the datasheets of buck converters, that the switching loop area should be as small as possible. Can someone help me on what would happen if the switching area is large ...
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1answer
35 views

Buck Converter Voltage waveform at the free wheeling diode cathode and anode

I am trying to understand the voltages at the free wheeling diode's cathode and anode in a buck converter. During the ON-state (as in the above circuit diagram), I assume the voltage at the diode's ...
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1answer
58 views

BJTs dangerously getting hotter as drawn current accumulating

I already ask a few questions on this project (so i won't explain everything again as it would be too long). I basically have a high power opamp (OPA462) to which i feed a signal (but i offset it ...
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1answer
23 views

Current burst limits for Calrod heaters

I am considering a design for a Calrod heater controller that delivers power to the Calrod in bursts. As an example, if I feed my 10 Ohm Calrod 100 VDC, it generates 1000 W. If I assume a 1 second ...
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1answer
31 views

Superposition Principle: Parallel Resistance in a current source

Good Day, I would like to ask a question regarding the superposition principle particularly when the current source is the only one active. The solution to this question is that when the current ...
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2answers
34 views

Can I connect Inductive Proximity sensor to two different input PLCs

Please, I´d like to know if I can connect a inductive proximity (PNP output) sensor in 2 PLCs inputs like the example in the image attached?
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1answer
92 views

Is there a more simple and less confusing way of solving laplace-tranformation equations?

The picture I have shared below shows the laplace transform of the circuit. The calculations shown are really simplified. I know how to do laplace transforms but the problem is they are super long and ...
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5answers
138 views

Which element determines the charging speed of a battery?

Which element makes the charging speed of a battery from 0% to 100% charged? Current (in A)? Voltage (in V)? Power (in watt), so the product of the two elements?
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5answers
229 views

Why impedance matching for only certain signals and not for other signals

I have a question. Usually, in normal communication interfaces such as I2C, SPI or even normal GPIO interfaces, we don't associate them with impedance matching. But for certain signals (I don't know ...
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6answers
761 views

Differentiator and integrator - without op-amp

I am trying to understand the working and function of the integrator and differentiator circuits using op-amps. Can someone tell me why we need to use op-amps for that function? Selecting just the ...
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3answers
73 views

Behaviour of a capacitor in a load powered by a constant current source

It's said that capacitors are open circuits when there's a constant current, but it's also said that capacitors resist a voltage change. So which of these two holds true in the scenario I described in ...
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4answers
2k views

Does the number of turns in Turns Ratio matter in transformers?

Suppose we have two transformers with same turns ratio, \$N_2/N_1\$. First transformer \$A\$ is of \$100:10\$ and the second transformer \$B\$ is \$1000:100\$. Both have same turns ratio so both can ...
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1answer
60 views

Building intuition on the behavior of inductors and capacitors with both voltage and current

I understand that an inductor cannot change current instantaneously, however I am not sure how that relates to the voltage. In a high pass RL circuit, for example, I know that the inductor presents a ...
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3answers
57 views

Why does the led turn on in the following circuit?

So i have connected a transistor as shown below where the base of the transistor is connected to the negative of the power source and the emitter is connected to the negative side of an led and the ...
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1answer
35 views

Low Current (<500mA) Transient Current Suppression Methodologies

I am looking into possible methods of protecting against small current transients for use with a laser module and am having trouble finding information, partly because I am unsure what exactly to be ...
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2answers
214 views

How does the inductor current ripple influence a switch-mode power supply?

I am looking into several DC/DC switching controllers. When talking about component selection, many datasheets and application notes say that inductor ripple should be kept around 20-40% of the ...
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1answer
159 views

If I convert the AC from a transformer to DC using 4 diodes and one capacitor and the same for another transformer and connect those DC out in series?

If I convert the AC from a transformer to DC using 4 diodes and one capacitor and I do it for another transformer and connect those DC out in series, what will happen? Is there any problem? How much ...
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1answer
52 views

What is the correct way to solve this DC RLC circuit?

I am studying for the FE Mechanical exam and am working my way through the electricity & magnetism section. Attached is a practice problem statement I found online and am having a bit of trouble ...
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1answer
52 views

Can a solenoid be used to create resistance in a wire

Would it be possible to have a solenoid connected to a DC source be used to "slow down" the current of a separate DC circuit with a wire going through the center of the solenoid with the ...
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1answer
68 views

Design of DC-DC Converters

While designing buck converters (or boost converters), why do we usually fix some percentage of the Ripple current (or ripple voltage) and from this percentage, we arrive at the value of inductor and ...
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0answers
234 views

Ammeter (DSN-VC288) showing wrong values

I am building my own RGB-LED-Strip (WS1812B) controller, including an Ammeter bought at my local electronics store to monitor the current consumed by the LEDs. On the back it can be identified as a &...
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0answers
41 views

Does a 12V cable of an ATX power supply have an overcurrent protection on its own when more current is drawn than the cable could withstand?

I want to use an old ATX power supply to power a project of mine. For that I'd like to utilize a single 12V cable from the 20 pin connector which is 18 awg and therefore can safely handle around 6 ...
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1answer
35 views

Testing results by running scripts on test equipment

In the context of testing circuits using oscilloscopes, what does it mean by running scripts and taking the measurements and results of the circuits? Has anyone tried to take results like running ...
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2answers
86 views

Microprocessor and Microcontroller - Why Micro [closed]

Just out of curiosity, we have these Microprocessor and Mircocontroller. I understanding these chips have some internal registers and peripherals to help us carry out complex tasks and functions. But ...
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2answers
97 views

Is there a thumb rule for the input and output capacitor for DC-DC converters?

If we are using a buck converter of say 5V 1A output, we definitely require input and output capacitors. Just without making any calculations, is there a thumb rule on what the values of the input and ...
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0answers
53 views

What is the effective value of the current of the voltage generator?

I need help with this task, if anyone had a similar problem it would help me. The task is: A voltage generator is connected to the primary of an ideal transformer, transformation ratio n rms values ​​...
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0answers
46 views

Current consumption of individual peripherals in STM32G070

I was referring to data sheet of the STM32G070 to figure out the current consumption of individual peripherals to finally calculate the power consumption of those peripherals. The following table from ...
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2answers
142 views

Precision current source 1 nA circuit analysis

I couldn't find any detail explaining this circuit. How would I change it to make it operate between 1 uA to few microamps? Would change 10 Mohm to 10 kohm would greatly degrade the performance? I can ...
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0answers
40 views

Why don't I get a bell curve in the torque vs rotor position plot?

I have designed a inset PMSM. I tried to plot the torque vs. rotor position plot but I am not getting a bell curve. Like at the torque must be maximum only when theta is 90 degrees. I don't know where ...
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2answers
122 views

Can a 48v electric bike battery be charged from a 4v or 5v Son 28 hub dynamo?

I want to ride an electric bicycle over long distances, including hills. I only want the motor for steep ascents. I am trying to stay off-grid as much as I can. So I would like to recharge the bike'...

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