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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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Ohm's Law in Practise

When the AUX pin of a stereo is connected to my mobile phone's audio female port, I just measured the voltage at the end of this AUX pin(No load is connected) approximately 2mV using a DMM . But when ...
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2answers
46 views

Help me understand what happens with the circuit when an AC signal is applied

Consider this circuit. Transistor is 2N2222A. Ic is chosen to be 10 mA. Hfe is 225 for that current. Resistors are calculated to have Vbe = 0.7V and Vc = 4.5V. I am trying to understand what happens ...
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3answers
48 views

thermal fuse as electrical fuse

I am trying to understand the spec of a Datasheet of a thermal fuse. for example the one below : https://nl.farnell.com/panasonic-electronic-components/eyp2bn134/fuse-thermal-cut-off-2a/dp/1832031 ...
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1answer
44 views

For measuring IV curves, could you use a current source and measure the voltage?

I was trying to find other experiments that required getting an IV curve but all of them seem to be applying voltage and measuring the current.
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2answers
60 views

True value of skin resistance

When I googled about skin resistance I find people mentioning values as low as 500ohm but usually around 10-100kohm. When i measured the resistance of my own skin by putting the probes on the inner ...
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0answers
39 views

Current derivative in RLC circuit

How to find the current derivative(di/dt) at t = 0+ in the first loop?
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2answers
45 views

Norton equivalent resistance of zero?

I am trying to analyze this circuit using norton. Load (20 Ω) is connected between A and B. I have removed the load and calculated the norton current to be -2A. Now I try to calculate the norton ...
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2answers
43 views

Does a current source have a difference in potential?

I am doing a nodal analysis of this circuit. I have found that \$ V_A = 10 V \$ and \$ V_B = -20 V \$ is it possible to have a situation like that? I mean a difference in potential between terminals ...
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3answers
42 views

In what kind of circuit does current flow?

In what kind of circuits do current flow? For a circuit to be "closed" does the end point have to return to the start point like in the first image? If you have a straight line conductor between two ...
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2answers
50 views

How do I calculate I2 by nodal analysis only?

I am trying to do a nodal analysis of this circuit. and I need to do this by nodal analysis only. I need to find \$ i_1 \$, \$ i_2 \$ and \$ i_3 \$. I have found that \$ i_1 = \frac{V_B - V_A}{R_1}...
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0answers
48 views

What is the maximum current a 13Amp twin wall socket can handle [migrated]

In my country a domestic wall socket is rated 13Amps. If I had a twin wall socket rated 13Amps does it mean that both outlets can handle 13Amps or the combined amperage of the outlets add up to 13Amps....
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2answers
34 views

Calculating charge entered into a circuit element for a given time

Looking at p 1.2-4 in Introduction to Electric Circuits by Dorf (See top of p16) I don't understand why the charge for 4 < t < 8 is 8- t. The current for that time is given as -1. So ...
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6answers
2k views

How do devices/appliances draw more current when needed?

Suppose I have a desktop computer and I decide to do something that requires more processing power. In this case my computer will draw more current to increase power. How is this increase in current ...
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2answers
82 views

Why does my phone charger consume more electricity (watts) when delivering less amps (slower charging)? [on hold]

As far as I could understand, the charging speed is measured in amps. Like, if I use Ampere, it will tell that it charges in 2.5 amps, or 1.5 amps. I hope I got this right. Amps is the only ...
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1answer
53 views

What is Maximum Average Forward Rectified Current? (1N4001 Diode)

I am wondering if someone can explain what Maximum Average Forward Rectified Current means for a diode. I see that this is marked as 1 Amp in the datasheet for the 1N4001. I have not been able to find ...
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0answers
61 views

What would happen if you hook up an A23 battery to your car ignition?

Both A23 battery and the car battery produce 12 volts of charge. So what would happen if you swap the car battery for the tiny A23 battery and turn the ignition? Would it spark? Go dead instantly? Be ...
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1answer
49 views

Voltage of pin set to high impedance? [duplicate]

Suppose a pin can be set to three modes, high (5V), low (0V), and high impedance (?V). What is the voltage associated with high impedance? I.e. if I stuck a probe on a pin set to high impedance, what ...
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0answers
29 views

Is it possible to boost the current using LT1302 dc-dc boost converter. Furthermore, the input current is in micro amp range

I am working in the area of energy harvesting. I want to know is it possible to boost the current using LT1302 or any other IC. The input current of the device is in microamp (2-3 microamp) and ...
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0answers
30 views

Howland vs instrumentation amp VCCS

I found an article on the Analog Devices site going over some different Voltage Controlled Current Source (VCCS) designs and I noticed an interesting one that used an Instrumentation amplifier along ...
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1answer
43 views

Doubt with current across several resistors (serie) and Resistor Power Rating

I have read that the current that flows across a circuit of several elements connected in serie is always the same but, as far as I understand, resistors consume current and disipates it in form of ...
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5answers
107 views

Is a 2 Ampere power supply dangerous? [duplicate]

I'm sorry if this question seems extremly dumb or/and pathetic. I'm quite new to electronics. For one of my electronics projects, I want to buy a power supply like this one, but it says Output: 12V 2A ...
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0answers
58 views

How to calculate the output voltage of the mirror circuit?

Please refer the following circuit added. Output voltage (Vout-A) is measured as follows, Following is the way I have started analysis: Krichhoff's voltage law around the loop ( R12 -> R3 -> V_BE(Q2)...
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0answers
20 views

Out of limit Touch Up current - Servicing PE

My device may not be connected to PE during normal operation, but does require 230VAC mains input. I know I have to take the touch up current of any Y-caps into consideration when developing my ...
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1answer
65 views

Did I ruin my multimeter with a current measurement?

I am trying to do a current measurement. Probably I accidentally put it it parallel instead of in series. What I tried before/after that (cannot remember exactly putting it parallel but might have ...
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1answer
55 views

Can a rocket igniter rated for 12v and 3 amps be powered with a 4v battery at 9 amps?

I have a rocket motor igniter that says it requires a 12 volt battery at 3 amps. Since power is I x V, and power is really what heats up the wire that starts the igniter, is it possible that I could ...
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2answers
48 views

Effect of electron discrete nature on current density

Coulomb’s law states that the current that flows through a wire is proportional to the applied voltage. For sure there are many physical effects (linear and non-linear) that participates in the ...
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0answers
56 views

Triac Equivalent or Substitute

I have a schematic which uses a triac, for example a BT136. Please have a look at the attached schematic (this is a schematic for a soldering station) What parameters from the datasheet we should ...
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1answer
59 views

How do I determine the unknowns for this equation?

Suppose a series RLC circuit in series with a 12 V battery and a switch initially opened. R = 100 Ω, L = 100mH and C = 10uF. L and C are initially discharged. A t=0 the switch is closed. I want to ...
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1answer
47 views

What is the meaning of current at infinite time for a series RLC circuit formula

I am reading this doc. At one point, the author says the current equation form a critically damped series RLC circuit when a step function is applied is: \$ I_L(t) = I_{\infty} + (B_1 + B_2t)e^{-\...
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2answers
762 views

If I convert 10 V, 1 ampere to 5 V, do I get 5 V 2 ampere?

I know the current in the circuit is the same. And also, Power = 10* 1 = 10 watts. So, 10 = 5 V * (x) ampere, X = 10/5, X = 2 ampere, With some loss while using a voltage regulator, I will ...
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1answer
20 views

Detect if 3-phase 110VAC motor is running via 24VDC PLC input

We have an industrial machine with 3-phase ~250W AC (~2.5A @ 110V) motors on it. I want to non-invasively detect if the motors are running. That detection signal needs to feed into the 24V input of ...
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1answer
74 views

Precision Current Measurement Using Arduino

We are designing a circuit to measure the current consumed by a Ultra-low power communication module. The requirement is below: Min current = 0.2mA Max current = 100mA Resolution = 0.005mA (5uA) We ...
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1answer
40 views

Confusing peltier efficiency COP/Volts and COP/Amps graphs question

Is peltier efficiency (COP) based on current and not voltage and could I have any voltage I want and get a high COP if I limit current? Whats confusing is that one graph shows efficiency based on ...
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2answers
62 views

Wiring for a 12V AC relay module?

I'm currently trying to automate my intercom system. My overall aim is to have it so that I can both detect when the buzzer has been pressed and then also to have it so I can open the door. I am using ...
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1answer
50 views

Finding the unknowns of a current equation leads to non-sense

Suppose a series RLC circuit that is critically damped. Circuit is RLC in series with a DC voltage source \$ V_S \$ and a switch initially open. Capacitor and inductor are both discharged. at t=0 ...
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1answer
38 views

How do I calculate the unknowns of the current equation for a RLC series circuit?

Suppose I was dealing with the following voltage equation for the RLC series circuit: \$ v(t) = Ae^{m_1t} + Be^{m_2t} + V_s \$ To know the values of A and B I would do the two initial conditions: ...
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2answers
48 views

Using of USB Cables for charging from adapter

Can a USB cable to deliver 2A current or 10Watts(2A×5V) power to a load especially in the case of mobile phone charging? Are the USB Cables available in market with different ratings? Is there any ...
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0answers
41 views

How much current does an LED in optocoupler draw?

I am planning to actuate the relay (opto-isolated) using the GPIO pins of Nodemcu. NodeMcu's datasheet says that maximum current that can be drawn out of a GPIO pin is 12 mA. Any load more that may ...
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5answers
188 views

Noob questions: I'm confused about conventional current and electron flow and how it runs through and powers a circuit. Can someone please explain?

My apologies if these questions have already been asked and answered, if it has then I haven't found the thread so please link me to it if it exists. I've just started learning about electricity as I'...
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1answer
59 views

Voltage across and current through the LED load

Assume that an LED of rating 3V and 20mA is connected in series with a resistance and a supply voltage of 9V is applied across it. For the required ratings of LED, I chosen a resistance value of 300 ...
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1answer
35 views

Mobile charging during low main supply [closed]

Due to some electrical issues in my locality, the supply voltage of 230V was unfortunately reduced to 110V. When I connected the 5V charger (Input: 100-240V AC; 50/60Hz; 0.2A & Output: 5V 800mA) ...
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0answers
25 views

Voltage and Current in Domestic Wiring [migrated]

According to European std. The domestic supply voltage is 220 V. When an equipment of high load current rating (Such as Kettle) is turned ON, the other elements such as 40W filament lamp is dim and ...
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1answer
61 views

Why use a star or delta connection instead of having a second output

I am winding my own small three phase ac alternator and have learned about star and delta connections. Should I use 2 three phase rectifiers to turn the current to DC or only one with a star ...
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0answers
16 views

2FORMC DPDT Relay gets stuck in middle

I'm trying to charge 3 batteries via 2xRS3s in parallel for charging the 12V batteries. I got in touch with manufacturer and said that they work well in parallel. The issue is, after couple times of ...
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3answers
97 views

Why are there current and voltage limits in a DC bench power supply?

I have a few questions about bench power supplies. Why does a DC PSU have a low output voltage limit, usually in the range of 18V-24V? Why is there a current limit built into the PSU? My ...
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1answer
58 views

Using neighboring traces for PCB return current

I am developing a 2-layer board for a 3-channel BLDC motor driver. I am using an IC for the driver (DRV8313). I will PWM it at 20kHz with around 10% or less duty cycle. Current is less than 1A. It ...
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3answers
154 views

Why does current have to return to its source in a circuit?

As far as I know there should be a current when a high potential point is connected to a low potential point, but apparently that is not true. I understand that a circuit must be closed in order for ...
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2answers
97 views

Could the extra power not used through a regulator or buck converter be used in another load without taking away power from the regulator? [closed]

I’m making a design for a crank generator which will charge my phone and a battery at the same time. The generator will be connected to a bridge rectifier, then a buck (step down) converter, which ...
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2answers
70 views

Does a splitter still reduce signal if only 1 of its ports is used?

I'm using a Wilson Electronics signal amplification system to try to get phone signal in my house. I'm going to attempt using a coaxial splitter like this one to split the amplified signal to multiple ...
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1answer
49 views

2 phase DC motor 2.8 A per phase

2 phase dc motor 2.8 A per phase, I want to use a 48VDC single phase power supply to power the motor, what current rating should I have for the power supply? Motor Spec (STP-MTR-23055): https://cdn....