Questions tagged [current]
Flow of electric charge - typically movement of charge carriers, such as electrons. Measured in amperes (A).
3,427
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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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23 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
69 views
why the voltage at the gate terminal is 1.8V irrespective of the 3.3V pull up? [on hold]
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1answer
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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
57 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
59 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
53 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
30 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 ...
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1answer
30 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
79 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
57 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
40 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. ...
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1answer
89 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
58 views
Light dimmer with capacitor [on hold]
I have a capacitor in series after a light dimmer. How could I calculate the voltage and current through the capacitor?
simulate this circuit – Schematic created using CircuitLab
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2answers
45 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
121 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
152 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
54 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
52 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
97 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
73 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 ...
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0answers
51 views
How to determine direction of current in a circuit?
https://imgur.com/a/wfeaznI
I thought current goes clockwise for each loop?
Even if we use the super position principle for the conventional notation shouldn't left loop look like: https://imgur.com/...
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2answers
55 views
How to precisely cap current
I'm building a device that drives a motor shaft with the possibility of injury or discomfort if the motor receives too much current. The motor will be driven at 48V with max current around 5.2A. It ...
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1answer
56 views
Replacing switch without transistors
I have a little keyfob style remote that I want to mod. It runs on a 3 volt button cell. I want to control the three switches with an ESP8266. The switches are connected to ground, and directly to a ...
4
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3answers
429 views
AD823 current sense
Refer the attached schematics.
Consider the details mentioned in it. I want to build the current sensing scheme using the part AD823 . enter link description here
I understand that offset correction ...
0
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1answer
71 views
Will my step-up converter module burn if I connect a power hungry device to it?
I recently bought a step-up converter module. It is rated to work at 24 volts and output MAX 28 volts and 2 amps. I will connect it to a source that outputs 5 volts and 20 amps. If I connect a power ...
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2answers
133 views
How is powering an LED with a 9 volt battery possible without burning the LED?
I used a 220 ohm resistor with a 9V battery and the LED works fine. However, most sources say the forward voltage in a red LED is typically only ~2 volts. Going by this logic, the LED should have ...
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2answers
50 views
Battery mAh and device operation
If a small signal electronic load is designed for normal operation by using say 1.2 V 630 mAh battery and if the same battery is replaced with say 600 mAh or say 700 mAh rating battery, does it affect ...
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1answer
76 views
Current limiting circuit
Kindly suggest necessary change to be made for current liming circuit for buzzer.
simulate this circuit – Schematic created using CircuitLab
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1answer
40 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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0answers
56 views
Why does moving this ammeter change the polarity of the applied voltage?
Note: I'm not an electrical engineer, I'm a materials engineer. So maybe this question has an obvious answer, but I couldn't find one with a Google search. I also have no idea if I tagged this ...
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1answer
33 views
Get expressions of E and H fields at a boundary from expression of surface current - Pozar ex 1.11
I am bringing whis question because, even though I have the solutions manual from the exercises of the book "Microwave Engineering 4th edition", by David M. Pozar (one of the Bible books for microwave ...
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1answer
79 views
Will 2000A Inrush Current Damage Outlet Circuitry?
First time building an AC control system complete with motors, PLC, sensors, power supplies. All this is sourced from a 220VAC outlet. I have calculated the total current draw of all motors, powers ...
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2answers
49 views
PIC16F88 digital output to gate of MOSFET - Voltage / Current questions?
I'm new to electronics. If I say anything that's presumptuous or just flat out weird or wrong, please point it out. There are many gaps in my knowledge.
I'm working on a simple personal project. I ...
2
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3answers
49 views
Brushless DC motor values at voltage other than nominal
I am currently using a maxon three phase BLDC motor (datasheet PN:412825) that is rated for 48 volts (see spec sheet below). I am running the motor at 18.5 volts (requirement for my application). I am ...
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2answers
82 views
Are current and voltage orthogonal in a transmission line?
If there is a phase difference on a lossless transmission line between current and voltage, is it always 90deg? Assume the Load matches the transmission line characteristic impedance.
If not what are ...
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3answers
50 views
Is the maximum current a resistance can draw limited by the maximum current available (current rating) in the power supply?
Let's say I have a single phase power supply at 100 V and 10 amps at my wall outlet. If I were to connect a very low resistance element (say 0.1 ohms), using Ohm's law I could say the resistance draws ...
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1answer
82 views
How can a light bulb run on different voltages (USA and EU)?
There is a concept in EE I don't understand.
In Europe we have a 230 V supply voltage and in the USA e.g. 120 V.
Now the thing I don't understand, how can I use my charger( or a light bulb) in ...
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0answers
20 views
High-torque low-speed switched reluctance motor: design Features
I am studying the design of high-torque and low-speed switched reluctance motors (SRM). There are classic designs (8/6, 10 / 8,12 / 8) and designs with multi-toothed rotors and with additional teeth ...
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0answers
25 views
powering a ESP32 with less current than specified [duplicate]
I'm building a device that uses an ESP32 + some LEDs + some 74 ICs.
It might require 150~200 mA.
I want to power it from an old computer (specifically, and Commodore 64) that says it can give 100mA.
...
2
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4answers
1k views
Can a DC brushless motor produce the same torque at different power levels?
I am looking these Neo Brushless motors for a project. Here are the links to the data sheet and also to stall testing from the company:
http://www.revrobotics.com/neo-brushless-motor-locked-rotor-...
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3answers
44 views
LED Brightness or Luminance is additive or not?
Let us say I have an LED whose brightness or luminance value is 50 Cd/m2.
If I lit 10 same type of LEDs with same conditions of current and voltage then will the brightness of these 10 LEDs will add ...
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0answers
21 views
Smart High and Low Side Mosfet
For example I have two smart high or low side mosfet that have 4 channel. One high side driver has 1 amper per channel. Other high side has 2 amper per channel. I tested these smart high side mosfet ...
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28 views
How to select power source for robot actuator with known torque requirement
I am building a robotic actuator that will be backdrivable, this robot will have pretty low RPM. I will be using brushless DC motors. I am trying to figure out requirements for the power source. I ...
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2answers
48 views
Finding a current in a given circuit
The problem has given the following circuit:
And asked to find the value(s) of Ix if the elements absorb the power(s) given.
I tired to set up KCL/KVL but I keep getting stuck.
I first drew this:
...
6
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1answer
117 views
Voltage Controlled Current Source - help needed
I am designing a voltage controlled current generator for the currents in a range from 0 - 2.5mA. The load resistance is within the range of 0 - 5k Ohms.
I decided to go with difference amplifier ...
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3answers
145 views
What causes a thorn like feeling when your put your hand in water in electronic appliances?
I live in India, the voltage supply in houses is 220V.
Sometimes, for example in my washing machine, when it is full of water and I put my hand in it, I get a feeling like a thorn/tiny nail is ...
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0answers
69 views
Does current in neutral wire flow like this? [duplicate]
I've read neutral wire in 1 phase AC at home has almost 0V at both ends. But still current flows through it. So I've assumed 0.1V potential at the other end near a resistance (bulb). Now there's a ...
