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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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0answers
29 views

Current consumption by 3-6V DC water pump [on hold]

If I use a submerisible pump of 3-6V DC and interface it to a controller via L293D. What will be the current consumption by pump? How should I calculate it?
1
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4answers
560 views

High resistance, no current. What's the point of a potential then?

I am referring to this example: Why does it matter that the IC has a high resistance? What does this do for/to the IC? If there is a potential but no current, what is the point of using the IC when ...
1
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4answers
39 views

Normalised Current Transfer Ratio of Opto-Coupler

My understanding is that the Current Transfer Ratio of an opto-coupler defines the relationship between the current flowing through the LED, and the maximum supply current of the output. e.g. "5ma ...
0
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1answer
23 views

Electrical noise on wemos D1 mini

There is electrical humming sound coming from wemos D1 mini v2 module. I'm using 5v 3A power supply connected to 5v input pin. I suspect its the current input which cause sparking/humming sound. ...
0
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1answer
49 views

Another Power Supply question

I am trying to troubleshoot a problem with a battery charger that accepts 11-18V DC input and can output up to 24V/8A/80W. The power supply I am using is rated for 12V10A, but if I select 10A 8.4V ...
0
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1answer
50 views

Amplifying Current from 0-20mA to 3A

I would like to drive a pump with a PLC. The PLC generates analog output signal of 0-10V with 0-20mA and the pump runs at the same voltage but 3A current. Is there any solution to this problem? Thank ...
0
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1answer
41 views

Boost Converter Output Ripple Current

I am designing a boost converter with the help of this TI app note My output Load current is 300mA and output voltage is 28V. I need to calculate the output ripple current. But in the app note, no ...
1
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2answers
28 views

Inductor Saturation Current and Temperature Rise Current

I have an inductor at the output of my boost converter. My output RMS inductor current is 271mA and the peak switch current is 1.3A. I have selected a 22uH / 2A Inductor as we select the inductor ...
0
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0answers
25 views

Mountain Bike Light Bar 18650 battery pack

I have a 6 Inch LED Spot Mini Bar Light which is used for vehicles, it uses 12-24 V and is rated at 18 W of power. I have some 18650 batteries which would work perfectly for this project. What would ...
0
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0answers
19 views

Finding current of circuit in steady state

I am unsure if I did the KCL correctly. Also if I switched from rectangular to polar without mistakes. Excuse me if the work is a bit sloppy I am new to the polar and imaginary coordinates.
0
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2answers
58 views

Will a live wire tester screwdriver work if I am hanging in air?

I have a very basic electric live wire tester. A simple device that otherwise looks like a screwdriver with resistor and a neon inside it. Image source WiKi I connect one end to the live wire and ...
0
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2answers
375 views

Will love to understand how the circuit works based on this schematics [closed]

Just a pure understanding of the workability of this circuit.
0
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4answers
71 views

How to reduce the current of a battery with an unknown maximum amperage

I'm currently trying to heat a wire to a certain temperature and tests showed that the amperage needed is in the range of 3-4 A. However, I'm having a problem with how to supply such current to the ...
1
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2answers
59 views

Devices drawing current

I was recently reading a passage discussing the effects of a replacement (mobile phone) charging plug. Suppose that the original charging plug is marked 2 A and 10 V and is replaced with a ...
0
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2answers
31 views

Does ESP8266 deep sleep make sense while on the power supply?

If ESP8266 is powered via a dedicated power supply 220V AC → 3.3V DC. Is it worth it to put ESP to deep sleep in order to reduce power consumption? For example the indoor weather station, which ...
0
votes
1answer
24 views

Current mode operation of a Source Measurement Unit (SMU)

I'm studying semiconductor parameter analyzers. In particular, I have difficulties in fully understanding the circuit in the following slide, which represents an SMU operating in I-mode (i.e., it ...
-2
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0answers
50 views

How to findout the value of V(s)/V(e)?

How to findout the value of V(s)/V(e)? Is it correct? $$\dfrac{Vs}{Ve} = \dfrac{\dfrac{R2 \cdot \dfrac{1}{j\omega C}}{R2 + \dfrac{1}{j\omega C}}}{R1 + \dfrac{R2 \cdot \dfrac{1}{j\omega C}}{R2 + \...
0
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1answer
57 views

Where does -1 in BJT’s Ies equation come from?

I don’t know whether there is already a question and answer to this but I couldn’t find one yet. Regarding the following information from a text: The equation for emitter reverse saturation current ...
4
votes
3answers
850 views

Resistor Selection to retain same brightness in LED PWM circuit

I am making a simple LED PWM brightness control circuit. I am using a relatively high power White CREE LED, N-channel Enhancement MOSFET BSS316N and Resistor R. The circuit is as shown below. I am ...
0
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3answers
80 views

Is there no current between these terminals?

This is related to charge carries movements out of transistor terminals. Assuming a transistor in common emitter connection is biased properly where resistors are omitted for simplicity. Before asking ...
0
votes
1answer
41 views

USB cable for power delivery max voltage

I have a USB cable with the following markings on it AWM 80°C 30V VW-1 28AWGX1P 24AWGX2C Inside the cable there are 4 wires. I would like to use the VCC and GND ...
0
votes
1answer
70 views

Peak open-circuit current and applied voltage of transformer function

I know that the back-EMF equation tells shows that the peak flux density is proportional to the AC supply voltage. But what is the explanation for that the open-circuit current increases non linearly ...
0
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1answer
39 views

Is this way of plotting AC current gain in LTspice correct?

I want to plot the AC current gain versus the collector current in common base configuration. Ac current gain "alpha ac" for CB configuration is defined as the change occurring in collector current IC ...
-2
votes
1answer
75 views

Ultra Stable Current Source At Up To 2 A [closed]

Can anyone suggest circuit(s) that can produce a very stable current source, preferably trimmable to close to 1 or 2 amps? Stability is the main requirement, all help is greatly appreciated. I have ...
5
votes
1answer
80 views

Are rated cable ampacities per conductor or per circuit?

I'd like to construct a cable using connectors DigiKey 708-1190-ND to connect a 20A LED to its power supply. The connector is rated "32A". In this example the connector's third pin will not be ...
0
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2answers
76 views

PCB problem - INA321 vias are too big

I am making a PCB using ULTIBOARD from NI. The problem is that I use a part called INA321 and for some reason I get the error that my vias are too close to each other when I place vias in the pads ...
0
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0answers
48 views

Current Transformers

I have a question about current transformers being used to measure AC currents. Say for example, we have a 50/5 amp current ratio, meaning that when there's 50 amps on the primary, there will be 5 ...
0
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0answers
38 views

Led driver compliance voltage

I want to design a led driver providing constant current to relative high power LEDS such as CREE XLamp series. These LEDs typically can be operated with 1A and upwards with a forward voltage of 12V ...
0
votes
0answers
18 views

Solving for open ckt voltage and short circuit current

I am unsure if I did the KCL for node A for the short circuit diagram correctly. I used the ia value from the open circuit and used it to find iy. Please let me know if I am on the right path or if ...
1
vote
2answers
58 views

Comparator as a current detector

I'm looking for a simple circuit that uses only a comparator (or an opamp) to detect the presence of a small current through a high-side current resistor. The idea is for a microcontroller input to go ...
0
votes
1answer
63 views

No Output Voltage On Power Mux

I am building a board based on a working reference design. I've obtained the assembled board based on my design but the '3V3_OUT' signal is failing to carry power anywhere on the board. The issue ...
2
votes
4answers
92 views

Opamp output to source and to sink

The output impedance of an ideal opamp is zero. The output of an ideal opamp acts as an ideal voltage source. The output of the opamp should be able to output very large currents (to source) and (to ...
0
votes
2answers
52 views

Confused on when to use RMS current or voltage in calculations (regarding rectifiers)

For question a, why is the power absorbed by the DC source : P=Vo*Io However, for the same exact question, the power absorbed in the resistor is P = (Irms)^2 * R Hence when do we use RMS current/...
0
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2answers
34 views

Class D amplifier - equation for peak current?

I'm trying to spec a power supply for a class D amplifier IC. I have figured out the maximum RMS current draw by taking the RMS power rating of the amp, increasing that to compensate for efficiency ...
0
votes
1answer
24 views

Do the dipole antenna edges have earth potential or is it a closed circuit made of co-axial cable?

I understand the shape of the dipole antenna, but how is it fed so that the current only flows through one direction during the half cycle? Even in a normal pole antenna, is there a ground at the edge ...
0
votes
1answer
31 views

Photodiode current vs. irradiance and finding upper limit current

1.) What equation could be used to calculate, or make a decent estimate of the current produced by a photo-diode from incident irradiance and its operating parameters. For example for this PIN photo-...
0
votes
0answers
18 views

LiPo ballancing circuit

I'm designing a circuit board to which I'll be able to connect multiple LiPo batteries (2-6S) and charge them in parallel without bothering user about balancing those packs firstly. So the charging ...
0
votes
1answer
55 views

How to write inductor ODE equation properly?

I've drawn a following scheme, and now want to write ODE system for describing inner processes, in order to explore it: simulate this circuit – Schematic created using CircuitLab I wrote the ...
0
votes
1answer
73 views

120 Watts and 7.2 Volts, how many Amps?

For a project I need to switch on a simple handheld vacuum cleaner with an Arduino. I am thinking of using a relay or mosfet. I opened the case and a 7.4 V 2200 mAh Li-Ion battery powers the motor, ...
0
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2answers
40 views

Determine efficiency, voltage, current from motor characteristic curves

I would to identify efficiency, voltage, current for a particular Brush less DC motor in our lab given characteristic curves. Electrical specifications are The operating conditions are ...
-2
votes
1answer
47 views

How to lower amperage? [duplicate]

I have a power source that gives 5V DC and 700mA. I need to power a ventilator that requires 5V DC and 500mA ± 10%. What is the best way to lower the amperage, would a 10Ω resistor do the trick or ...
12
votes
2answers
1k views

Why is current rating for multicore cable lower than single core with the same cross section?

As per this resource, a single core 10 AWG (5.3 mm2) copper cable is rated for up to 52 amps, while the same cross section cable of 43 cores and more is only allowed to carry up to 15 amps. Why is ...
3
votes
3answers
154 views

bldc motor, esc and battery draw, nominal vs peak

I want to better understand how Electronic Speed Controllers (ESC) work for BLDC motors. Specifically, I am trying to understand battery current draw. Question 1: When an ESC is rated at 200 amps ...
2
votes
1answer
86 views

Confusion about current flow

I'm trying to understand how the charging of a plate capacitor works which lead me to question my understanding of current flow. In many explanations, it is said that the voltage source pulls the ...
8
votes
9answers
3k views

Negative Resistance

I am a bit confused about the physical meaning of negative resistance. Mathematically, a component which has negative resistance shows a decreasing voltage across its terminal when the current inside ...
0
votes
1answer
22 views

Stepper motor phase current driving confusion

So, I was studying a bit about driving current for Hybrid stepper motors and was faced with some ambiguity related to the Full Step excitation. In this reference, https://www.researchgate.net/...
1
vote
4answers
101 views

How to overcome over-current in a circuit?

I have a relay switch that operates at 10 A and 120 V connected to a DC motor that runs at 18 A and 36 V. Will the relay switch burn out? If so, how can I protect the relay switch?
0
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0answers
51 views

Peltier behaves strangely

I've been trying to test my Peltier moodule (tec1-12706) with 2 1.3V batteries (2.6 in total in series) connected parallel to the module.. ...
0
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2answers
64 views

Is it possible that a load can be destroyed if I am disconnecting all other loads in the circuit but one?

I consider myself as a beginner, so please don't be that hard to me. Can I theoreticaly destroy a unfused load if I disconnect all loads but one in the same circuit? In my understanding the current ...
0
votes
2answers
54 views

Calculating charge given current and capacitance over time

I it possible to calculate the charge on a capacitor when only having the current, time and capacitance value? I tried using this formula to first calculate the voltage and from there the charge. ...