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

learn more… | top users | synonyms

0
votes
2answers
50 views

Copper brushes?

I noticed the superior choice would be a carbon based brush,however, is pure copper brush a bad choice? I'm considering copper due to the lower resistance and higher current carrying capacity. I ...
2
votes
3answers
139 views

Does an antenna violate the principal of a circuit having a return path?

Seems weird that an antenna has no return path. Also, what about capacitive coupling. How are these circuits?
1
vote
1answer
38 views

Calculating resistance of an electric brush

For a certain application, I'm using carbon based brushes to transmit power from a stationary component to a moving component. I'd like to calculate the resistance of the carbon based brushes to know ...
1
vote
2answers
59 views

Best way to deal with surge in current from DC motors

I have a Li-po battery 12V 9800mAh (typical current 2.4A) which powers a 4WD drone using 4 DC motors (which I have not yet characterized). Driving the motors from still to max speed without ...
-5
votes
1answer
28 views

Is there is any harmful effect if I am using 2 amp instead of 1 amp [duplicate]

for my dish tv set up box. I am using 5 volt 2amp ac/dc adapter instead of 1amp. Is it okay? Or harmful? That dealer said to me that I can use higher amp. Please reply. ...
0
votes
1answer
56 views

What Type Of Switch Is only on for a second [duplicate]

I am looking for what type of switch is only only for a split second (1 second max) even when held. Basically: Press and hold button-->LED only on for a split second and back off even though I am ...
0
votes
0answers
23 views

L200 with NPN pass transistor help!

L200 datasheet: http://www.zen22142.zen.co.uk/Circuits/Power/l200.pdf In figure 24: There are two transistors, one BDW51 and one BC108. I was wondering what is the use of the second transistor ...
0
votes
0answers
41 views

voltage and current mode

I am reading about voltage mode and current mode from the book excerpt here. There is one part about current mirror that I don't quite understand. Could anyone explain it more details? A unity gain ...
0
votes
1answer
86 views

short circuit - Time constant calculation

In calculating Tao,why can't you ignore the shorted resistors? capacitor goes to natural response when the gate shuts. \$\ v (t) = Ve^{t/T}\$ here T, is \$\ T= R_{eq}C \$ Since there is no ...
-1
votes
2answers
50 views

How do I increase DC current from low to high by decreasing the resistance? [on hold]

From my understanding I know that the power has to remain constant. So if I have an input of 20 watts of power, the output has to have 20 watts of power. But how exactly do I increase the current in a ...
0
votes
0answers
39 views

Single Buck Regulator for Multiple Circuits

Currently working on a project that involves 4 separate circuits that light up LEDs on one tail light PCB in an automotive application. Due to the high cost of a buck regulator circuit, we have ...
0
votes
0answers
26 views

PMOS calculation with active in rush protection system

Here is a schematic i made. It is very basic. It aims to command a PMOS when the Switch (at left) is pressed. A the output (connector 01x01) a H4 bulb will be connected. Low power part is regulated ...
-7
votes
0answers
41 views

Power supply with voltage and current selectors [on hold]

Is it possible to create a power supply with voltage and current control through something like knob selectors? If there is, can I have a circuit diagram example?
2
votes
2answers
84 views

Charging time of lithium ion batteries

I am charging a 430mAh lithium polymer battery at 1C using BQ24232 charger IC (from Texas instruments). The charge terminates within 1 hour 20 min with battery voltage showing 4.17V. On research I ...
0
votes
1answer
36 views

Quick question about the L200 circuit limit

I need some help on how to calculate the output current.. Datasheet: http://www.zen22142.zen.co.uk/Circuits/Power/l200.pdf I want to use the (Figure 2. Programmable Current Regulator.) But i don't ...
0
votes
1answer
48 views

DC fan current requirements

Very basic question here that I thought I knew the answer to until last night, but now I am very confused. I picked up some 12v DC squirrel cage fans for a chassis I am building. Here is the Mouser ...
-3
votes
0answers
59 views

Possible to shut off power using magnetic fields? [closed]

I've been considering a theoretical scenario similar to Ocean's Eleven, where they used an EMP to kill power to a city to get into a casino. Considering the effect that a magnetic field has on the ...
0
votes
1answer
54 views

How much amps (maximum) are flowing through 1000Base-T Ethernet? [duplicate]

How much amps (maximum) would be flowing through a 5 meter Cat 5/6 Ethernet cable with 1000Base-T speed (IEEE 802.3ab, 5-PAM coding, so voltage levels vary between +- 2V, 1V, 0V)?
0
votes
2answers
54 views

Dealing with FreeWheel Current

In the schematic below, I would like to know the best way to dissipate the FreeWheel Current in the very shortest time possible. simulate this circuit – Schematic created using CircuitLab ...
14
votes
3answers
1k views

Lithium Coin Cell CR2032 battery specifications

I am using a CR2032 battery module to operate a BLE 4.1 module. The BLE radio for communication takes around 3.5ma to 5ma of current. But when I look at the datasheet of the battery ...
0
votes
2answers
119 views

simple IC for on-off current detection?

I am trying to identify an IC that can sit in proximity to an appliance power cord (120VAC) and simply detect if current is flowing or not. On-off output is fine; no need to actually measure the ...
1
vote
1answer
66 views

Remove the load of buck converter

I have a buck converter that is delivering 6A to a load of 3ohm load. I'm measuring the output current and stop increasing the dutty cicle when the current reach 6A, at this moment the output voltage ...
0
votes
0answers
30 views

By measuring the electricity generated, is it possible to calculate how fast the turbine was moving?

Say a wind turbine is moving at varying speeds. From the electricity it generates, would it be possible to calculate/replicate the motions of the turbine? How accurate can these measurements be? Will ...
1
vote
1answer
82 views

what is the use of a resistor in the PNP transistor?

The R3 is connected to the output of the PIC, I could understand the NPN transistor but PNP was a bit confusing. When the transistor starts to conduct, some current will flow towards the base. My ...
0
votes
1answer
46 views

Battery charger disconnection

In modern devices (mobile phones, tablets, laptops) the battery charging current is automatically switched off when the battery reaches 100 %. After being disconnected, the power supply cools down. It ...
0
votes
1answer
39 views

Analog signal vs. Alternating current

I am seeing that both of the analog signal and alternating current is represented by the same graph: As far as I think I know, an alternating current travels back and forth with gradual changes in ...
-4
votes
0answers
13 views

Main to 12v adaptor to power motor [duplicate]

What adaptor should I use to run a 12V DC High torque motor (60 RPM) on the mains (240V)? Thanks for your help Salomé
0
votes
2answers
75 views

Transformer drawing 29x more current than it needs

I have an old transformer (20+ yrs) in a building I manage (GE Model 9T23B3872), it takes 277V 3-phase and converts it to 120V 3-phase. It seems very wasteful. It is drawing a combined 8.7 A @ 277 V ...
3
votes
3answers
97 views

why does sources with same voltage drive different current through same load?

I have three mobile phone chargers with rating 5V 500mAh, 5V 1Ah , 5V 2Ah. When I charge my phone Mi 4i with these chargers , the charging time is different. It means all these chargers drive ...
1
vote
5answers
116 views

Difference between current and power

I am a bit confused about the difference between current and power. I am hoping someone can explain the difference to me maybe using an analogy or something. I do understand that current at a point ...
0
votes
2answers
71 views

How to calculate the base-current of this transistor?

Newbie in eelctronics here. How would you calculate the current trought the base of the first transistor? simulate this circuit – Schematic created using CircuitLab follow-up question: ...
-3
votes
2answers
97 views

How do I know if I need a resistor or not? [closed]

I have bought a Sound Bomb from Maplin. On the bottom of the device it says: Voltage (DC): 12v Voltage Range: 6-15v Current: 85mA If I want to wire this ...
0
votes
1answer
90 views

Can you really commit suicide using a toaster? [closed]

In numerous fictional depictions, people commit suicide by dropping a toaster into a bathtub full of water with themselves. Does this actually work? In particular, since electrical current travels ...
-1
votes
0answers
88 views

Why do PC fans in parallel slow down? [closed]

I can run one fan at full speed when connected directly to a PSU (can supply up to 27A on the 12V rail, so current draw isn't an issue). When I connect another fan, both fans run slower than full ...
1
vote
1answer
73 views

confused about pnp transistor current flow

I am new to electronics and this question might seem silly.... see attached image please. I do not understand why in the transistor below current seems to flow from collector to emitter... because ...
3
votes
2answers
710 views

How does this current limiting circuit work?

A tutorial electronicsArea explains a transistor based current limiting circuit. Problem is that I am not able to understand how T1 gets switched on in the fist place. To make T1 on it needs a ...
2
votes
1answer
47 views

How to select a gate driver transformer

I designed a Half-Bridge power supply using Gate Driver Transformers to drive my two MOSFETs. It's working great, I winded the two transformers around very small toroids with some turns, I didn't ...
0
votes
1answer
32 views

Current draw on 12 volt power supply [duplicate]

I have a 12 volt power supply rated at 250 amps for my landscape lights. If I switch to led's with little current draw will the power supply still draw 250 amps or only what is required of the ...
3
votes
2answers
338 views

what is a ground? [duplicate]

I have a basic question about electronic ground. For example, if electrons travel from the DC battery's negative terminal through the conductive wire to the positive terminal of a DC battery with a ...
0
votes
0answers
26 views

What are the risk of overload a inductor in buck converter?

I've a buck converter working at 100kHz simulate this circuit – Schematic created using CircuitLab So far I have tested the circuit for a 4A output current, but I may need to work with ...
-8
votes
4answers
58 views

Current division with more than two parallel resistor

According to the current division rule, if two resistors R1 and R2 are parallel then \$ I_{R1} = \frac{R2}{(R1 + R2)} \times I \$ . In this case which resistance value should I pick for the ...
0
votes
3answers
79 views

Extremely high current power source(s)?

Out of curiosity, is it possible to have a current source generating extremely high current? In the magnitude of 100kA? With low voltage output since the resistance would be 0.1 micro-ohms. It's very ...
1
vote
0answers
32 views

BJTs drawing collector current from a limited current source

simulate this circuit – Schematic created using CircuitLab Let's make everything ideal by ignoring the voltage drops: Q1's allowed collector current is: 22.4 mA Q2's allowed collector ...
0
votes
1answer
50 views

Amplifiers output current

I had read in TCA0732 datasheet that its current supply can't be greater than some decades of mA (+14mA for +15V voltage supply) but it can provide 1A of current how can that be possible, the same ...
0
votes
0answers
67 views

BLDC Motor : Control Speed digitally using Microcontroller

I am stuck with a logic to control the speed of BLDC Motor via Microcotroller. I have a BLDC Motor with Electronic fitted. It requires following signal to drive : +24v 0v or GND Enable ...
0
votes
2answers
57 views

Power Draw of a Small Transformer

I couldn't find the answer to this anywhere so, how can you tell what the power draw, in amps, of a transformer is knowing the input voltage and turns on primary and secondary.
0
votes
2answers
59 views

Charging a capacitor with low current

Supposing I have a small solar panel rated at 5V and a supercapacitor rated 5.5 V 1 F, would it be possible to charge the cap fully? Or in general, can a cap be fully charged with a low current, ...
0
votes
2answers
46 views

Parallel motors on the same output

Am I getting motors correct? I'm building a third party psu for a slot car race track. Obviously easy bit is transforming 240Vac down to 12Vdc. But I am unsure how thiswill react with my motor. THe ...
0
votes
1answer
59 views

Safest way to limit current output of a signal generator

I need to feed a TTL-like signal (0-5V) from a signal generator to another equipment (herein 'load'), whose manual states that the input current should be about 10 mA, and 30 mA maximum. As I work ...
0
votes
1answer
73 views

Why do over-currents destroy IC's?

Power driver IC's (like the L298) have absolute maximum ratings for peak current, continuous current, and temperature. I get why overtemperature could cause the IC to fail, but, assuming I kept the ...