What is Dc: Definition and 1000 Discussions

The call for papers has been announced for the AAPT 2018 Summer Meeting in Washington DC (Jul 28-Aug 1, 2018). http://www.aapt.org/Conferences/sm2018/abstractsubpage.cfm . Abstracts are due on Feb 21. Unfortunately, I don't think I'll be attending this meeting.(Future meetings: 2019 Winter...

Homework Statement Write down the equations of motion and develop the continuous-time system. Homework Equations See my word doc. or PNG's. The Attempt at a Solution See my word doc. or PNG's. I assumed that there was no friction as no information was given. I can easily get the transfer...

Homework Statement Homework Equations V = IR And R becomes 2(r of one conductor) because of return path. The Attempt at a Solution V minimum is at third junction. At VD Using KVL we get: [/B] Drop at AB = (10 + 20 + 50) * 2 * 0.1 = 16 V Drop at BC = (20 + 50) * 2 * 0.08 = 11.2 Drop at CD =...

Homework Statement Homework Equations The Attempt at a Solution I think External char = Magnaetic characteristics - Armature reaction drop - Ohmic drop since we're subtracting these values from voltage. But book answer is D. Magnetization char + armature reaction - Ohmic drop. Is book...

https://en.m.wikipedia.org/wiki/Marx_generator I chose the prefix to get an educated answer. I am not school educated but rather self taught, also instead of focusing primarily on electronics I have studied for the past several years the broader spectrum of electromagnetic phenomena including...

Homework Statement Homework Equations Efficiency = o/p divided by i/p I/P KW divided by input voltage gives input current Field Current = voltage divided by field resistance armature current = total current - field current Back Emf = V - IaRa T proportional to Ia Back Emf proportional to...

Hi All. I'm having trouble working out the solution to this problem. A Synchronous motor is coupled to a DC Compound Motor. The DC Machine is rated for 220 V DC. Its Armature Resistance is 1.0 Ω . The Synchronous Machine is a 4 pole 400 V 50 Hz 3 Phase AC Machine with an efficiency of 80%...

Hi guys, can someone please have a look at the following problem that I am struggling with; An 8.25 kW shunt DC motor is supplied with a terminal DC voltage of 300 V. The armature resistance of the motor Ra is 0.25 ohms, and the field resistance Rf is 40 ohms. The field winding consists of 1500...

building a DC supply with a load voltage of 3.3V and load current of 3.3mA. all the books and schematics I'm seeing is that they're putting the fuse in the primary of the transformer, why? if i were to fuse the primary as well how do i get the rating of the fuse that i'll need? its said in my...

So this is an example given to me in one of the guides. I am somewhat confused as to why R and R1 are considered parallel when the switch is closed at t=0. I thought that the two resistors cannot be parallel since there is a voltage source between them. One hypothesis I had was to treat it...

Homework Statement I am asked in a lab report to explain the conservation of power in the armature circuit of the DC motor. Homework Equations This is the data I have acquired: The Attempt at a Solution I have been reading around, and I have learned somewhat about the Armature Copper Loss...

I didn't understand the following: The relationship between ##V_{CE} ## and ##I_C## is linear. In active region, even if the ##V_{CE}## increases, ##I_C## remains almost same for a given ##I_B##. So, how can the relation between the two can be linear? Can anyone tell me the utility of the...

Hi in every theoretical explanation of any kind of DC motor there's always a split ring commutator and two brushes like in the following pic then when it comes to my motorbike/car starter motor rebuild the real thing in practice is different- see the following pic with four carbon brushes- two...

Homework Statement Design, giving the necessary ratings and characteristics necessary for the transformer, bridge rectifier, reservoir capacitor and regulator, a 12 V, 2 A regulated power supply. Also identify any heat sink requirements. The available mains supply is 230 V ±10% @ 50 Hz...

Hi. As far as I know, the main reason for using AC in electric power transmission is that voltage can easily be transformed. If there was a similarly easy way for transforming DC, would power grids work basically the same? To be more specific, how much does AC power transmission rely on the...

If take a simple dc motor and connect the negative side to let's say a insulated metal plate. The other side directly to ground and you then turn the shaft of the motor. Would you force all of the free (loosely using all) electrons in the insulated metal plate through the motor to ground giving...

In Action Comics #867, Superman survived the explosion of a sun What I would like to know is, how much energy was he exposed to? - I know there's the Inverse square law to consider - And I know because of that, he did not get hit by the entire energy of that explosion because his surface...

I need to measure current in DC system. I have circuit breaker (125A), so 150A shunt is selected. On that shunt ammeter is connected. But that ammeter has 60mV, scale 0-150A. What does this 60mV means on ammeter? Is it correct?

Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply. The DC link is just a capacitor so that: dVDC/dt =...

Homework Statement Homework Equations[/B] I have a circuit that consists on 3 components in parallel: a current source Ia, a resistor R and a capacitor C. Ia is directed upwards, while the currents through the capacitor and the resistor are both directed downwards. Select the correct option in...

Lavolta BPS 305 0-30V and 0-5A. I was showing a young lad how you can energise a car ignition coil and get a spark on the output, and that this effect can be improved by adding a cap in parallel which forms a crude LC oscillator etc when the unit died. Silly, I know, but we got a bit carried...

This question involves finding the transfer function for the system, but I first need to get the differential equations correct. Have I set up the gearbox correctly?

I have a power supply which takes 230 VAC input and gives 24 VDC output. I use it to drive some differential pressure sensors (24 VDC supply and 0-10 VDC signal output). It is stated to have a noise of 80 mV peak to peak. This can equate to a 25 Pa variation in readings I'm finding with...

Hello! I have to use a relay to operate circuit breaker opening/closing coil i.e. 80W @ 110VDC. Since the breaker is having some mechanical interlocks, so sometimes when the coil is operating, the breaker may not open. In that case the relay contact has to make & break the opening/closing coil...

Hi everyone, just found these forums and had a look around, there's some great info here! I usually deal with the run-of-the-mill industrial three phase motors so this is not my strong suit so please bear with me here. I have a large DC motor here that was brand new but failed after about 2...

I want to wire some LED strips to the bass speakers in my car so that they will light up to the music. I reason that you can't wire the lights in parallel with the speaker because the lights can blow with too much volume. I also read that it will trash the sound quality. ? Anyway, my plan is to...

1. The problem statement, all variables and given I do not have a clue where to get the information to built a DC motor with four electromagnets Homework EquationsThe Attempt at a Solution

Homework Statement For an engineering assessment (first year with no electrical background), we are using a solar panel to power an element for a distillation system. we have calculated our heat energy output requirement that we need from our heating element as being 800 J/s. For simplicity we...

Homework Statement Homework Equations The Attempt at a Solution I used the loop rule where ##ΣΔV=0## and junction rule. From here I get 4 equations ##i_3=i_1+i_2## ##ε-i_3R_3-i_1R_1-L(di\dt)=0## ##ε-i_3R_3-i_2R_2-Q\C=0##...

I have been working on some projects, I build a glass grinder, faceter with a 120v induction AC motor. Its not possible to effectively change the speeds with electronic controls being a single phase motor. It is using belts and pulleys for now. So I am wanting to build several tools, rock...

I have to check whether my circuit producing a burst of 500V in CRO. How can I check whether CRO is capable of handling this high voltage? I have heard about HV probe, how to check the probe that I have is of HV type?

Hey all, A 'rank' newbie here, so please bear with me. ;-) I have a 'solar charged' 12V battery (with charger) for an electric fence charger. I'd like to use this solar charger and battery to power a 12V AC (I think) low voltage landscape bug zapper. It 'must' be 12V AC, I think? Is there...

What are the two methods for calculating large DC motor efficiency ?

Hi, I am modelling a DC motor using Simulink. Under no-load conditions, I get a max speed of 180 rads/s, but under load, the speed goes up to 290 rad/s, although takes longer to reach max speed, acceleration decreases. I have a mechanical background so don't know much about motors, but would...

Okay, this is probably going to be way below your pay grade, but bear with me because I know nothing about electric motors except that you plug them in, turn the switch, and they work. I've seen some instances where people have taken DC motors from treadmills and used them to power lathes and...

When choosing Line Codes (e.g. Bipolar or Polar formats) for transmission of bits over a communication channel such as twisted pairs, it is always desirable that no DC component is present for a particular choice. According to William Stallings (Digital Communication Book) "With a dc component...

Please i need help on a simple method of converting DC to AC The desired AC output is to power a mini laboratory incubator

Homework Statement Homework Equations The Attempt at a Solution All loops are clockwise; KVL Loop around 1V, 120kOhm and VBE (I1 is assigned to the loop): -1V + 120kOhm * I1 + VBE = 0 I1 = IB = 0.3V / 120kOhm = 2.5 * 10-6 A; Loop around 10kOhm, vCE (I2 is assigned to the loop); KVL...

While the motor is spinning, I measured the voltage (Vrm) across the motor by connecting the two probes from the multimeter to the two terminals of the DC motor via alligator to alligator banana cables. Since the current was fairly constant, I could ignore the inductance. So, no voltage across...

Hello, on the internet, there are various methods on measuring the inductance. For example, http://www.dos4ever.com/inductor/inductor.html and https://electronics.stackexchange.com/questions/182116/whats-the-easy-way-to-measure-a-dc-hobby-motors-inductance If I want to measure the inductance...

Hi, we know that the speed varies inversely with the torque. The more the torque, the lower the speed. From torque-speed curve, we can calculate the slope. When the applied voltage increases, the straight line shifts upward while when the voltage decreases, the straight line shifts down. How...

Hi all, so my mercury 25 outboard starter was starting to give it up. I took it apart, and yup, the brushes were badly worn. Well, I have several generic brushes kicking around, so I simply swapped them out. Very simple operation. And yet after assembling the damn thing, it now runs backwards...

Hi, For my project I am plotting a Force vs Displacement graph using 2 analog inputs which are going to a DAQ. The two analog inputs are coming from; -A 5k potentiometer (for the displacement) -A 1000 lb load cell sensor (for the force) I would like to use a regulated 12V DC (1Amp) power...

I have a 2 AMP regulated DC power supply, with variable voltage 3 - 12 v. If in a small circuit, i.e, small copper wire with 1 ohm resistor. Why am i not getting at max Amps?

Today a professor of mine who teaches Electrical machines told us that a DC series motor should not be started without load. I wonder why is that so. Please provide a detailed explanation of this PF members. Thank you very much in advance.

Hi, I want to measure the motor resistance of a gear DC motor by experimentation and Ohm's Law. Should I measure the current without the gear head, with the gear head, stall current (with gear head) or stall current (without gear head)? I am trying to obtain values for Equation 4 in...

Hello, I appreciate if somebody could help me to resolve this. I bought a geared DC motor from a store. I would like to obtain the following information: Resistance, Inductance, Back EMF constant, torque constant, and the voltage caused by Back EMF when the motor is supplied by a voltage input...

I have seen some relays mentioned as 110V AC/ 24V DC relay. Is this means, can I use both 24DC and 110V AC to the coil of relay?

Hello, I want to model a DC motor which I bought from a company. I only have the following information: torque constant [M.N.M./Amp], EMF constant [MV/RAD/SEC], Dynamic Resistance [OHMS] and Motor Regulation [RPM./M.N.M.]. The company does not provide the moment of inertia nor elect/mech...

I need to combine two DC voltages to scan and lock a laser. The scanning will be 0-100 V and the locking will be performed with a small correcting voltage, +/- 1 V. Both of these will be fed into a PZT driver. My advisor suggested using an opto isolator, however I am not sure how that would...