# Questions tagged [current]

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

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### Kinetic Energy and Inductor energy violates conservation of energy?

I posted this question on the physics page however I feel like it might be better suited to this site. Suppose we have an ideal LC circuit (no resistance) and an open switch where the capacitor has an ...
0answers
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### AC 3 phase servomotor current mode

How do i mathematically model a 3 phase ac servomotor's current control mode? someone please help me. The model of the the servomotor is BSM132C 5200AA Thanks
2answers
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### Does my total power supply voltage need to equal the sum of the voltages in my circuit in series?

If I have let’s say, 4 bulbs, each rated at 1.5 volts and they’re all connected in series. Would my battery need to be rated 6 volts? My logic is that each bulb would have a voltage drop of 1.5 volts ...
1answer
28 views

### Deviation in the switch current in a flyback converter

This is the current waveform of the switch and the Vds of the MOSFET. Ideally, the current should fall off in a normal fashion with the switch turns off. Here, the current fall stops and becomes flat ...
1answer
83 views

### What is the flow of current with two parallel voltage sources?

Good day ! I am a physics student and not an EE so I'm quite hesitant with approaching this circuit problem. What will be the equations for this analysis? Will their be current in the red line even ...
0answers
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### Circuits with diodes shockley equation

I am using the Shockley model to evaluate the current through a diode and the voltage across it and I have this circuit and this is where I am stuck: simulate this circuit – Schematic created ...
1answer
25 views

### How to estimate the current driven by this uC board for this operation?

I want to power this uC board through its E5V power input pin as shown in below table: The power source for the E5V pin will be the +5V Vcc pin of this FTDI converter. And in its datasheet the ...
2answers
54 views

### How to size overcurrent protection?

I'm a begginer in electronics so I have some very basic questions. I would like to protect an OpAmp power supply rails from overcurrent. But I don't know at what value I should set this protection. ...
2answers
130 views

### Question of current with multiple current sources

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab My question is this:How much is the current from I1 through R1? I guess it is 500mA because I2 is an ...
1answer
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### Isn't conventional current supposed to go from high potential to low potential ? If yes, then why this rule is not respected in opamp using AC?

First, thank you for reading my post. I'm a beginner in electronics. I learned that conventional current goes from high potential to low potential. It has always worked for me in DC and even AC. But ...
1answer
48 views

### Capacitors current options

About capacitors the formula Ic = C*dV/dt refers to the displacement current or to the current which charges/discharges the capacitor?
2answers
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### Can two IRLZ44N MOSFETs in parallel handle a current of 20 A without heat sink?

Can two IRLZ44N MOSFETs in parallel handle a current of 20 A without a heat sink? The Vgs command is a square wave at a frequency of 70 Hz. Do I need to attach two big heat sinks or not? Will my two ...
1answer
36 views

### How can I calculate current with load switch? [closed]

I want to use a load switch for protecting my PCB. I also want to watch/measure the current drawn by my board. How can I sense/measure the current drawn by my board, using a load switch like the ...
4answers
61 views

### Understanding power ratings

So my previous question here confirmed what I thought, to calculate the power dissipated in a component, take the voltage across the device and multiply by the current. But why do some devices have a ...
0answers
42 views

### Modes of operation of P-JFET

I have the conditions of the operation of the N-JFET But I can't understand how we can find the expressions for the P-JFET.Are they opposite?Help appreciated
4answers
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### Nodal Analysis Current Direction Matters

simulate this circuit – Schematic created using CircuitLab I'm currently doing a question and it appears to me that the direction of the current matters. For both the batteries I've assigned a ...
2answers
52 views

### Input Ripple Voltage and Output Ripple Voltage for Capacitors

I'm working with Buck converters and Boost converters separately. Can someone tell me the reason why the output ripple voltage (and current) exists in the Output Capacitors and how does the input ...
3answers
353 views

### Is it necessary to connect relay contact at voltage zero?

While disconnecting relay contact, it is recommended that the action should be done at or near current zero. As the contact area decreases rapidly, a spark is generated due to high current density. ...
0answers
49 views

### JFET question about operation

I have a question about the N-JFET.Assume it operates at the linear region and it acts like a voltage controlled resistor. Can we say that if Vdg(drain-gate voltage) is increased then the resistance ...
0answers
49 views

### Kirchhoff's Current Law on two nodes

Can anybody help me with the balance of the currents on the nodes A and B of the this picture? Here is what I obtain: ...
2answers
40 views

### The definitive method to probe the device operating current

How can I measure the current a device consumes? I tried one that has 1.5 V power supply requirement. I measured its resistance with a DMM from the power supply box (with the batteries removed) by ...
2answers
50 views

### Is running 4 18650 batteries in parallel too much current for a small RC circuit with the same voltage?

I built this small RC deadbolt lock and everything works great, however, I need to fix the issue of battery life before it is finished. Originally the circuit had a 3.7V, 800 mAh battery. I would like ...
0answers
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### MOSFET Switching Loss Formula

I'm trying to calculate the switching loss of the MOSFET which is used for a DC-DC Boost converter. Input Voltage : 9V-16V Output Voltage : 30V Output Current : 0.3A. Switching Freq : 455kHz Based on ...
0answers
43 views

### Power distribution problem in multi-camera usb array

Problem Summary My MacBook Pro (development system) can successfully capture images from 24 cameras in the multi camera assembly we have assembled. But when our assembly is attached to a new Raspberry ...
2answers
44 views

### How to Find the Thermal Resistance Junction to Ambient

I have this BUK9M12-60E MOSFET. I have calculated the maximum power dissipation of the MOSFET to be 14W (Conduction loss, Switching Loss and Gate Loss). I believe that I don't require any heatsink. I'...
1answer
82 views

### Increasing current with constant voltage

simulate this circuit – Schematic created using CircuitLab I got a sine wave from an STM32 DAC. Its voltage is 2.64 V. I wanted to amplify it. I used this schematic. Its gain is 4.3. I got 11....
1answer
47 views

### Constant Current of an XL4016 Buck Power Module [duplicate]

Hi have this buck converter : Step Down Buck 9A 300W Converter 5-40V To 1.2-35V Power Module XL4016 I've done my research, read some posts and articles but I'm still quite confused, some say a ...
1answer
53 views

### How is data transferred through wires? is it [5,0] volts (DC) or is it [1,-1] volts (AC)?

So basically I am learning about how data is transferred through wires for a networking course and I stumbled upon this Ben Eaters video on this topic and I got a bit confused because I know that ...
1answer
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### Is this network able to be interpreted as a node and apply KCL?

I've may been asking the really trivial question. Is above diagram correct? I interpreted the network as a node and applied KCL. No such grounded thing is included in the network.
1answer
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### Confusion in minimum gate triggering current of SCR

I was reading an article about working and properties of SCR from eleccircuit.com and in a section How to pick a SCR -it is written that we should check its rating and one of the mentioned rating in ...
1answer
74 views

### Are these 2 equations some of general formulas of infinitesimal length?

Given below. $x$ is a variable. $r:=\text{resistance between the nodes A and B}$ $l:=\text{length of the resistor }r$ $\rho:=\text{resistance per unit length of }r$ \\$\frac{1}{\rho'}:=\text{...
1answer
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### Why there was no power to an electric cloth dryer? [closed]

The other day I stumbled on something very puzzling to me. I installed a 3 prong dryer cord on a previously working dryer and as I plugged it in the wall outlet the dryer would not turn on. I was ...
2answers
103 views

### LED open and short detection

Can someone tell me on what how to detect a short circuit and LED open circuit for the below circuit? Is it possible to detect which LED? Could someone provide a circuit which would help to detect an ...
0answers
44 views

### Capacitor Lifetime

Can anyone some sample calculation on how to calculate the lifetime on an Aluminum Electrolytic capacitor who's Endurance value (Assumed as Lifetime value is 2000 hours at 105degC). The manufacturer ...
2answers
144 views

### BJT in saturation mode equations

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab The BJT transistor is in saturation mode.Which are the equations which help us find the different ...
1answer
40 views

### DC Output current control [duplicate]

Can I use a 14v 2A dc adapter on 12v 1A dc rated device? Now what i did is by a buck controller i set the voltage to 12v but there is no variables to control the current in that buck control module. ...
0answers
32 views

### How to determine the lowest bound of current sensor sensitivity?

I would like to build current logger using Arduino. I am having hard time finding out and understanding the lowest bounds of current sensor sensitivity. The following link states sensitivity this way &...
1answer
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### Why will this circuit not work? I need a perfect reason [closed]

Will this bulb light for nanoseconds?
1answer
57 views

### CCM, DCM and BCM - Inductor

In a boost converter, what is the factor that determines whether the power supply (dc-dc converter) will be in the CCM, BCM or DCM mode? Because, I have an LED Driver A80604. And I am trying to ...
2answers
40 views

### Boost converter inductor selection - inductor ripple current calculation based on input current or output current?

I've a question regarding the inductor selection in a boost converter. In this TI App note under Inductor Selection on page 3, it is asking to assume the inductor ripple current as a percentage of ...
1answer
53 views

### How to control the output current in when using a transistor as a switch?

Assuming that I have the following circuit where I use a transistor as a switch: When the transistor is not active Vout will be equal to the Vcc and the current will become very high right? So if I ...
1answer
83 views

### How can I reduce 120 VAC 60 Hz gradually to zero in a 8 seconds?

Need help on a project where after a pressing a button 120 VAC voltage drops gradually to 0V in 8 seconds. Second button will restore full voltage again. Load is a big magnet and its current can be as ...
2answers
46 views

### Confused about photodiode current

I am confused about the photodiode current voltage diagram. According to this diagram the current at zero bias is down->reverse current.How is that even possible? At photovoltaic mode isnt the ...
2answers
58 views

### Dithering Circuit using an Op-amp

I am reading and trying to understand this Application note from TI on how the dithering circuit works. I can deduce that the Op-amp acts as a schmitt trigger but there's no details on how the ...
1answer
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### Dithering Modulation Frequency and Dithering Rate

I have a question regarding dithering. I was reading this Application note and under section 4.1 page 5,they have given below, I understand that we perform dithering in the DC-DC Switching converters ...
2answers
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### LED driver operation vs boost converter operation

I am having this A80604 - LED Driver IC for driving a string of 9 LEDs. Each LED has a forward voltage drop of 3.1V and a forward current of 300mA through each LED. So, I need to generate a maximum of ...
2answers
53 views

### What kind of gps battery can I use for uBlox NEO-M8N GPS module?

What kind of gps battery can I use for uBlox NEO-M8N GPS module? Would you please recommend gps battery? and Which can I use 5.5mAh or 11mAh?For example; MS621FE-FL11E - BATTERY LITTIUM 3V 5.5MAH (...
2answers
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### How can it be 12VDC and 1.2A 30W?

I came across a device at home which has the specs bellow written on it: Rated Power: 30 W Rated Voltage: DC 12 V Current: 1200 mA Since P = V × I, P = 12 × 1.2 = 14.4 W Why on the specs it says 30 ...
1answer
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### What do these forward currents at specified wattages mean?

An LED I'm looking at has various specs listed that I can't make heads nor tails of. It is listed as a "3W LED" supporting a 2.5V minimum and 3.6V voltage. However, "Forward voltage&...
1answer
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### Oscilloscope can't detect voltage and waveform

I am having a trouble with my research. I am using a function generator to deliver electrical voltage to a wire and when I check it with the oscilloscope, it detects nothing (waveform, voltage.) Is it ...