What is Dc: Definition and 1000 Discussions

Hi. Assume we have some circuit with resistance ##R##. In DC, the current ##I## linearly depends on the connected voltage ##V## by Ohm's law ##I=V/R## . In AC, we can independently connect any voltage and current to the system by using a transformer, provided we have a power source with...

Hiz lets assum we have a load fixed on the roter of a the 'DC series motor' in the attached photo, where: Vt: DC source voltage (constant) Lf: field's inductive resistance (will be neglected) Rf: field's resistant Ra: Armature resistance Ia= Armature current, If: field current M: back emf (Ea)...

Hello, I was reading about the differences between Current Source Converters and Voltage source converters. One main difference was that Current source converters need to have a minimum DC power flow of 5-10% while VSC do not have a min flow requirement. It was also called a deadband. Why is...

What are some effective ways to convert a Pulse Width Modulation from a Microcontroller to a DC Voltage as a function of Pulse Width? 1. Use a low pass filter to remove the unwanted harmonics and leave only the 0th term of the Fourier Series. What produces a better DC Voltage an Active or a...

I am making a some sort of an electric vehicle (cart) that will be used to move things around the two story warehouse. I am trying to figure out what would be the minimal power of an a DC motor, considering that the max speeds will be up to 10 MPH, while being able to push forward to the second...

I read this statement from Lenard Audio. "When a large signal spike is created by un-plugging or plugging in signal leads, or when a pre-amp valve is driven hard into distortion (guitar amps), a large non-symmetrical square wave may cause a temporary DC Voltage to appear across a coupling...

I want to design a device that will require a small dc fan that may have to operate for long periods with fog-like moisture passing through it. Is there any advice on what to look for?

Hello all, I'm building a miniature vehicle and plan on using a DC motor that supposedly spins at 12800 rpm (1340 rad/s) for the engine. However, I'm a little confused as to what the car's acceleration would be. The DC motor on its own would instantaneously have an angular velocity of 1340...

Hi there everyone, I'm doing some study on electronics and the section on the advantages of A/C over DC mentioned that AC has less copper loss (I^2 x R), But to me this seems contradictory to the skin effect. Could someone please tell me why AC has less copper loss.

Alternatives to varistors as overload protection at DC motor DC Motor here implies 12V linear actuator w/DC Motor that consumes 2.8A under loading condition. Pretty costly equipment. I'm using a L298N motor driver connected in parallel to run the linear actuator. The motor driver is run by a...

Hi, I realized I didn't understand the physical model of something I know the theory of pretty well. I was considering the real power loss of an AC transmission line I2*R, then I realized that from source to load the electrons in an AC line don't actually move anywhere. (as far as I know) Yet if...

Hi, so I salvaged a 220v, 6.5 amp DC permanent magnet motor from an old treadmill and I was having some trouble with it. I believe that AC motors can simply be run from mains power (I have an AC motor from a dryer that I cut the wires from in order to bypass the circuitry and essentially...

Hi I thought I remember reading that transmitting power over 800km's is passed the break even point for DC vs AC. And I read that modern rail is starting to use 25KV AC, but aren't many networks bigger than that, specifically in NSW Australia, the according to wikipedia it's 815km, I'm not sure...

Hi I'm looking for a suitable high voltage prob for my research project. I'm in contact with voltages that can have transient spikes as high as 3.0kV but my DVM only measures up to 1kV and 97% of the time I am under this range. I bought this and it was perfect the only problem is that it has a...

Problem: my photo diode receives pulses of width 10ns-150ns and repeating at rate of 1Hz-50KHz the current from photo diode depending on incident light can go from 10nA-100mA, so i have two photo diodes to cover the dynamic range, what i want to do is limit the current from a photo diode to...

My brother is a high school student tasked with making a DC motor. It is finished and works however I thought for the sake of learning and the additional cool factor (I'm relatively new to this field), I could make an optical RPM sensor which I could tack on. So I made this...

Hi, Could I please get some conformation and clarification: So the more phases an inverter has, the less ripple will be on the DC bus, and the higher the switching frequency the inverter is operating at, the closer the approximation is to a sine wave. These are the advantages? But what are the...

A large number (56) of 18 gauge-ish connection pins are presented by the connector. They are wired together in large groups on the "client" side of the connector (4 electrodes). We wish to re wire these groups together and then split them off into 24x 18 AWG a few feet removed from the...

I am doing a project where I need to control brightness of a led light. according to presence. the brightness can be controlled using pwm but I cannot find a way to do that for high voltage input signals.

Homework Statement {Moderator edit: The unlabeled resistance is given to be 3.2 Ω } finding v1 and v2 at t=0+ and t=0- is needed Homework EquationsThe Attempt at a Solution ok I've found the currents by mesh analysis but how can i get the voltage?What voltage is in the inductor or capacitor...

Hi everyone, I am a little confused conceptually about electrostatic voltage and DC voltage. I did my bachelors in biochemistry (where I’m working today), I’m learning/relearning physics as a hobby. I did well in high school physics and first year physics but I’m afraid I’ve forgotten most of...

Hi, I am doing a design project but I'm kinda stuck with choosing motors because i am not sure of the required torque. My project is a handicapped golf vehicle powered by 2 motors, so it would need to be able of climbing steep gradients. I currently have an equation but I am not entirely sure if...

Hello i am abeginer i have to connect a 12v dc motor can i connect it to two 9v batteries in series meabs a total output of 18V.

Homework Statement :Find the current that go across the diode ans=0.86mA[/B] Homework Equations V=IR 3. The Attempt at a Solution The Vt(v total) is 30v so,must i ignore the diode as off first?.In that case the current is 30/20=1.5 mA. i also know the that diode is foward bias because...

My goal is to make an electromagnet that delivers 100mT magnetic field on one end of the iron. The iron core has a diameter 2.0mm and length 0.1m. I am using a copper wire that can carry 2.3A of current, and I am using a DC power supply. I have been able to create a 100mT magnetic field on the...

Homework Statement I need to get 7 equations to make a 7x7 matrix in order to solve it. I have 4 of them, but I'm not sure how to get the voltages equations. Homework EquationsThe Attempt at a Solution I have got four equations so far. One is simply using KCL, I1 = I2 + I3 + I4. The other...

Homework Statement I'm trying to solve this circuit when I try to simulate and run a dc sweep i get that it can't be solved. When I try to find the answer using linear algebra I get this answer after I throw it into MATLAB with the warning “[w]arning: Matrix is close to singular or...

Homework Statement Homework Equations no equations required The Attempt at a Solution so here are my answers, i just want to know if they are correct. also, I am really confused about the function of the commutator in the DC motor, the answer i wrote for part b) was based on research off...

Hey guys, I know I still have a tread unanswered but I got a project in which I have to include some physical theory about the working of motors. I know P=V*I and also P=T*W where V is voltage, I is current, P is power, T is torque and W is angular speed. My question is, can I say V*I=T*W?. I...

I have noticed there are a few designs for permanent magnet brushed DC motor, but I can't seem to find the benefits and downsides of either one. The first one (first attachment) uses three electromagnets placed on a triangular rotor. There are two arc permanent magnets on the outside. In this...

Homework Statement There is a current of 3.2A flowing through the 20.0ohm resistor...(the questions along with my work are attached below). I am having some trouble with DC circuits, especially those that include a combination of series and parallel circuits. I have worked through the problem...

Homework Statement Hi, I am having some trouble with DC circuits, especially those that include a combination of series and parallel circuits (networks). There are a couple of problems that I have worked through, but have no idea if I am on the right track and have the correct answers. My work...

Why voltages out of the rotating loop is constant positive and negative **Why nOT varying like sinusoidal **. Like it has a wave form of O to 2*vBL and then it maintain its value there for some time before failing to zero and changing direction. I have attach the image file from my book...

How to build Non-contact DC Voltage detector/sensor?

Hi, I'll start by offering some context to my question. I am a mechanic by trade, and have a bachelor of technology in motorsport engineering. I have a friend who is an electrician by trade, and he likes to work on his car in his spare time. In my line of work I only deal with 12V/24VDC...

Hi I am currently making a pool heater and i have a comodated an old air con unit i have come to a point on the circuit board where i am stuck. I am makeing a controler to send a signal to the outdoor heater but the out door heater has a 240v ac supplie and 1 live 12v DC signal cable. But...

Hello, I just came across this site when looking for some info. Not sure if this is a stupid question but I would like to know what the correlation between AC and DC power is when comparing one device. For example if i had a a device connected to 120vac and it drew 500w then the amps would be...

I cannot find answers to this on the internet. Can a d/c be made using an armature? How? How does one convert a/c 2 d/c (or d/c to a/c) thirdly, why does the band a/c d/c come up as the first result on google? (don't answer the last question.)

Homework Statement initial problem: A 228 −Ω resistor and a 586 −Ω resistor are connected in series across a 90.0−V line. A voltmeter connected across the 228 −Ω resistor reads 24.0 V . Find the voltmeter resistance. For Req, i got Req=228R/(2+228), R being the resistance of the voltmeter. But...

figure 1 shows dc model of CB transistor, why is it that collector diode is taken as current source in equivalent circuit, why not emitter is also taken as current source ?

Homework Statement Homework EquationsThe Attempt at a Solution I know from a basic magnetic circuit that their will be an Rcore and an Rairgap but what about the rotor in the middle ?

I've been trying to figure out why my DC subtraction amplifier is not working, and am completely baffled. I have set up an op amp with no feedback resistors with voltages applied to both the inverting and non-inverting inputs as specified below. I previously had the op amp setup with a 10x gain...

Hello forum. I'm looking for a DC motor for a little project. I don't have a lot of experience with different types of motors, though I'm fairly confident I don't want a servo motor or a stepper motor. I have a disk of non-uniform weight distribution. I want to mount the disk vertically (motor...

I am currently ‎building a simple visible light communication project. ‎ My issue is with the ambient light in the room. The Vout of my photo diode amplification circuit shows a square wave carrying the data on top of a varying DC level depending on the amount of ambient light . ‎ I have read...

How can this DC motor work without a commutator. Should it not turn no more than once and then stop because on one side the rotor is attracted to the magnet? An answer I can think of is that the rotor is repelled on one side and attracted on the other by the same force which neutralize each...

Hi, I'm sure there are such devices both factory made or diy versions , basically what I need is a relay that switches on a few secs after the power supply itself has turned on, because there is or can be a voltage spike occurring during the first few moments when the power supply is switched...

I am ploting bode of resistor connected with DC source.So no freqvancy at all! The bode magnitude plot should be(or it should start from) 20*log(jw)=20*log(0) (jw=0 because we have dc source) what should be the value??for step of 5v... what should bode look like??

Hi all, Building a frequency offset locking circuit for laser spectroscopy. First electronics project so been hitting a steep learning curve. Long story short, I have two branches in this circuit that take a AC signal run it through a diode and low pass filter to measure the envelope and output...

OK. On datasheet of transistor 2N4401 there are many DC current gains (hFE). Which one is useful. I want to use it over 5V and 60mA.

I'm doing a project where I need to hand power one small, dc motor (1.5-12V) and charge a 1F 5.5V super capacitor, and then use it to drive another small 1.5-12V dc motor. Does anybody have any suggestions for motor specifications or circuit elements that will help me get the most efficiency...