Dc Definition and 1000 Threads

Hi. I am curious about ways to sense the position of a rotor in a BLDC motor. I am familiar with hall sensors and back emf but am wondering if there are other ways to find the position of a rotor maybe more accurately. I had an idea about using a laser and a photoresistor around the...

1. An inductor of negligible resistance and an inductance of 0.2 H is connected in series with a 330 Ω resistor to a 12V d.c. supply. Determine: (a) the time constant of the circuit (b) the voltage drop across the inductor after two time constants (c) the voltage drop across the...

Computer brush fan as dc generator Sir, I am using renewable soℝurces like wind for my project.. I need to supply 1.5 to 2 v dc to my amplifier circuit and then to load... I am using computer brush fan as source ...it just gave output upto 2.5v in ideal state when i connected to multimeter...

I have attached the picture of the circuit. I'm trying to figure out the steady state voltages across the 2 resistors and the capacitor. V_s is given to be 10V DC. At steady state in a DC circuit, a capacitor acts as an open. When that happens, we shouldn't expect any current to flow...

Hello, All! This is a thread that should address my questions and evolve into a general discussion on AC and DC for the purpose of interest. My first question is: What did Nikola Tesla add to the field of electronics and AC? I've read all over the web two conflicting ideas 1) Tesla is...

conflict: why synchronous machine doesn't produce induced EMF in the DC field wires Isn't it current path through winding which produce magnetic field (rotating) the must produce EMF in the dc winding of field (same theory of induction) but why isn't true in synchronous

So I have a Gr 11 Physics Science project. I need to build a Brushed DC motor. I already build an armature with coils. I have a copper commutator and copper are connected to it. Lastly, I placed electric tape on the wood body The problem is that I don't know how to make an effective Brush...

1. In the network given (Fig.1), the initial voltage on C1 is V1 and on C2 is V2 such that v1(0)=V1 and v2(0)=V2. At t=0 the switch K is closed. (a) Find i(t) fo all time. (b) Find v1(t) for t>0. (c) Find v2(t) for t>0. (d) From your results on (b) and (c), show that v1(∞)=v2(∞)...

A Wheel of a self balancing skateboard of radius 7 cm is rotating at 2600RPM with torque for motor is 1.76Nm,current is 10.4Amp and 24v and total load is 90kg (10kg for skateboard and 80kg for user). What is the speed of self balancing skateboard the in km/hr with load?

I've made a simple DC motor like this image: http://farm4.static.flickr.com/3156/2864655414_234d5d3207.jpg I'm just confused why initially when i increase the number of loops (about 15) it spins faster.But after this limit the speed of the rotor is no longer as fast as it was before. Why...

I have to build a device which have 4 dof governed by 4 separate motors. Need to remotely control which was the motor spins and when to stop them. What equipment do I need? and is there any guidelines? Need help asap. Thanks,

I work as an engineer and I've been looking for an explanation for something that I have been puzzled by. Physics background of problem: In brushed DC motors, electrical coils (poles) rotate as the motor moves. A change in inductance as they move makes small variations in motor current...

I have been studying the plans for a few AC to DC converters and I understand that the basic conceptual design is one where the AC power is transformed to lower the voltage and is then passed through a bridge rectifier to convert that power to what I call hopping DC. The power is then smoothed...

Homework Statement A shunt generator has an armature resistance of 0.8Ω, a field winding resistance of 120Ω and a mechanical loss of 115W. The load resistance of 8.5Ω is connected to the output terminals of the generator. An external mover rotates the shaft of the generator at a speed of...

Why is it that the air gap flux density is flat topped at no load. What happens to it's shape when machine is loaded?

http://img823.imageshack.us/img823/9775/picture2mq.jpg Uploaded with ImageShack.us Hi I can't get my head round Kirchoffs law. I've been alright with series and parallel circuits with one voltage supply, but I've been given a problem with two voltage supplies. Would anyone be able...

Hi there Currently in my physics class my teacher has assigned us a project where we are to make a DC motor using these items: 2 thumbtacks 1 meter of 14 AWG copper wire 2 paperclips A block of wood 1 ceramic magnet 1 AA battery 2 connecting wires My plan is something like this...

Homework Statement We have a small car that is powered by a battery that feeds a DC-motor. The system consists of two DC-to-DC converters that controls the rotor and stator current. The DC-motor i separately magnetized. The purpoce of the DC-to-DC converters is to modulate the time the...

I've a small wind turbine that is rated at about 24V. The turbine produces AC voltage but it's got an internal recifier converting this to DC. I need to create an embedded system that measures the output of this turbine displaying AC voltage, current and power output. I did some research...

I have an application where I am using a 24V DC motor to drive a ball screw. If someone isn't paying attention and they hit the mechanical stop on the ball screw, the current is going to spike to about 200 Amps. The normal running current is about 35 amps, and the max current is 60 amps...

Homework Statement I want to find the overall transfer function of Instrumentation amplifier with a DC-Suppression filter. I know how to calculate the TF of a normal Instrumentation amplifier. But when feedback is given from the Filter to the IA, I couldn't find it. Homework Equations...

Hi, I am trying to use Matlab to analyse this raw signal by introducing Dc-offset analysis: I used the following code : a = [1 , -0.98]; b = [1,-1]; y = filtfilt(b,a,x); figure plot(y) And the result : But, I am trying to get a final result similar to the last graph...

Are they shining brightly inside the device when used to convert ac?

Hello All, Could you please explain what would happen if I charge a capacitor with say 30 khz DC 500 volts with a 10000 uf cap. Would a gas discharge tube, varistor, triac of 300 volts connected across the capacitor help to preventing it from exploding? Ged

I was recently informed that AC is the preferred method of transmitting power because it suffers significantly less power loss going from the generating station to where ever it needs to go when compared to DC losses. In my introductory electricity class we learned that power through a given...

Hey, I am working on a science fair project and I have an electrolytic cell that will produce hydrogen. My goal is to measure the energy input and output to calculate the efficiency of the cell. Right now I am trying to find the best way to calculate the input energy. I am in the process of...

Hello! I found a cool site to buy odds and ends electronics. It sells RF wireless remote systems equipped with relays. With halloween coming up this will be really fun to play with }:) . My question is, the description states the relay output is 125V VAC but if can't I run VDC through it...

What steps I have to follow to find the DC gain of the second order system with a transfer function ? Putting "0" where I see "s" or taking the limit as "s" goes to infinite ?

Hello everyone For a project I'm currently working on, I need a dc motor which can generate a torque of about 0.1-0.2 Nm (or more) with a rpm of about 120-200...

Hello all, I am trying to get my head straight about wiring multiple DC voltages together. I should know the answer to this question, but I thought I'd ask someone else. If I have two DC power sources...Source A is 12V 1A and Source B is 5.3V 980mA...and I want to combine A+B to get the most...

Ok, I'm new to electronics and have some pretty simple questions that I can't seem to find answers to elsewhere. Let's say I have a DC motor that I want to use as a generator with the following specifications: 130 VDC 17 A 5950 RPM I know that in order to generate 130 Volts, that would...

Hello All, I'm designing a circuit board that needs to run on a 12VDC supply and will need to supply a fair amount of power to drive a bunch of 12V relay coils, in addition to some electronics. Since I want to keep the voltage drop on the supply a small as possible, I thought about using a...

Homework Statement Write down formulae for dX in terms of dA, dB, dC if: X = [(A) (B^2)] / C Homework Equations I'm using the formula below as this corresponds to this relationship. (dX/X)^2 = (dA/A)^2 + (dB/B)^2 The Attempt at a Solution For the first line, not the...

Actually this not a question, I want to justify whether my concept is right or wrong. So let's start. Faraday's law of electromagnetic induction e=Nd\varphi/dt explains the way of electromagnetic energy conversions. The induced voltage is always ac because the rate of change of flux is...

Homework Statement Inductor, resistor and a capacitor is connected to a DC source in series. DC source is 220 V Capacitance is 10F Inductance 5H Resistor 22 ohm Vc(0) = 50V Question is asking for the charge time of the capacitor, when it gets charged fully and then it starts to act...

Homework Statement Given the no-load test results of a DC motor connected in shunt to be: Speed: 3000rpm Applied voltage: 239V Field current: 0.25A Calculate the motor constant K_m, where K_m = K Homework Equations not really sure about the equations to use i have these: Km = T/...

Hey guys. I made myself a pulse circuit but my power supply failed. Now I need a way to use a 12v magneto as a power supply. But a magneto puts out pulses. Can I put a capacitor or a diode there to make it a steady stream of dc current? This is for my go kart 5hp briggs. for turn signal...

I am new here and don't know if this is appropriate so let me know. I am not an engineer and no formal training other than a few Physics classes in college many years ago. I do however have a high mechanical aptitude and have always done some personalization of machines. Eg. I put a lawn mower...

Hello, I am an automotive technician so I work with a lot of 12volt DC motors. First, it seems to me that bad connections or wires can cause excessive voltage drops to motors, but I don't understand what the difference is between a good cable and a bad cable. Or what qualifies a good...

To increase a DC generator's turning effect, we increase the number of turns of the coil. How does this increase the turning effect? Will it concentrate the field lines or will the force acted on each coil be added to each other to increase the force on one armature? I think both happens because...

I was wondering whether there was any literature on brushed DC motors used as a generator or whether you know anything of the sort? I know that DC motors behave differently when used as a generator instead of a motor. However I have not been able to find anything about it so I was wondering...

Hi, I have a question related to the DC motor that i hope you geniuses can help me with. By Fleming's Left hand rule, there is an induced forced (IF in diagram) at the downwards position at the armature AB. Thus, by Fleming's Right hand rule there is an induced current (IC in diagram) which...

Ive been given an assignment with the question being question 13of the following pdf: http://vlsi-eda.cm.nctu.edu.tw/course/ICT_12Summer/hw/HWCh4.pdf (note this isn't my actual assignment i just found this one on the internet that happened to be the same question that i was looking for) Im...

Does the back emf in a dc motor start to appear after a slight delay(say 1 or 2 seconds) after starting up the motor? I have had this simple doubt for a long time.According to the "generator principle" both applied emf and back emf will always exist simultaneously.Also it would be in violation...

I need help in answering the post lab questions given to us by our professor. 1. Is dc beta constant on every point of the characteristics? What is its effect in the linearity of the transistor? 2. What is the effect of a high dc beta on the characteristic curves? I have attached an...

Can we Earth ground AC and DC voltage? would this effect the components on the system?

Homework Statement For an AC generator, my teacher told us that when turning it, you will slowly manage to turn it at a constant speed only because of the induced current causing a force in the other direction to the turning motion. Why is this so? For a DC motor, my teacher told us that after...

HeyoO everyone (^_^) and Thanks for your time. Homework Statement This question is about the "intial" point of time i.e. as soon as the key is closed. Before the current starts to flow which charges the capacitor till the voltage of capacitor is equal to voltage across the battery. A...

Homework Statement A 1kHz square wave with an amplitude of 2V (peak to peak) is applied at the input V-in of the circuit shown. The resistor R1 = R2 = 10 kΩ, and C = 0.02 μF. a) What is the effective time constant of this circuit? b) What is the minimum and maximum voltage reached at...

Hello, Im using DC motor to run the conveyor but suddenly the armature shows high current 130 A for 30 V power and the speed can't increase anymore. The motor power stated in the name plate is 93.8 KW, Armature voltage is 453 V and Armature ampere is 225 A. The motor can run free load after...