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1

Why and how this mysterious AC voltage is created ? The transformer has stray capacitance, this creates some leakage in itself, but worse it interacts with the switching action of the converter in ways that lead to the PSU acting as a high frequency source between input and output. To prevent this high frequency interference being radiated from the PSU ...


0

Use mechanical relay. Input AC and output AC or DC


1

Do not install power cable next to communications cable. This is against the electrical code in most countries. In Australia, our Wiring Rules (AS 3000) specifically require power and communications cables to be physically separated, either by barriers or by distance. If the power cable is damaged, and shorts to the communications cable, then the ...


1

simulate this circuit – Schematic created using CircuitLab Figure 1. A double-pole switch or relay solution. If you review your schematic you will find a few problems. You have two independent AC supplies where in fact you probably only have one. You have no return path from the solenoids other than through another series-connected solenoid. The ...


0

In the context of the power grid, AC power is generated and transmitted through transformers in three phases 120 degrees apart. The third harmonic (triple the frequency) is identical for all three phases, which you can verify by plotting the sine waves. When you connect a load between any two phases, the third harmonic voltage is the same on both wires, so ...


1

Homework, I guess, a theoretical one which assumes ideal stator and no substantial saturation nor stray inductance effects. The general induction motor theory tells: In that ideal case max. torque occurs at slip=R/X where R is one phase resistance (=load + rotor wire) and X=one phase rotor reactance. Actually also negative slip = -(R/X) is valid for max ...


0

There are two effects which may be contributing to your results. Firstly, a DC generator does not produce smooth DC. The output is actually a combination of all the individual armature coil AC voltages, rectified by the commutator. It is similar to the output of a 3 phase rectifier, but with switching noise and flat spots where the brushes short between ...


0

What waveform does the motor give when you rotate it? If you know the waveform, you'll understand the multimeter readings. For most (cheap) multimeters the DC measurement gives you the average value of the waveform, or the DC component and the AC measurement gives the RMS value of which the DC component is blocked, so, not the true RMS. I made a setup up ...


0

It raises the gain of the overall circuit as often one MOSFET can't increase the gain dramatically. Also taking a quick look at your drawing did you forget the source resistors? It'll separate the FETs from ground and alter your resistances. For example the vgs will be nonzero so the dependent current sources will have to be taken into consideration. Google ...


0

If using two different DC brush motors, one to drive the other. The output V*I=P, power out is still less than the input ( due to losses). But it works as a DC transformer with the sum of both motor impedances in series. Most motors are rated in V/kRPM, Volts per 1000 RPM for no load, thus the sum of series impedance affects the output voltage by the load ...


3

Absolutely! That is the basis for motor-generators, which, before power semiconductors, were one of the few devices able to change DC voltage with comparatively little loss. Of course, stepping up voltage comes with a concomitant reduction of current, so you don't gain any power. E.G. 12 volts at 30 amps is equivalent to 120 volts at 3 amps, 360 watts. ...


0

You will run into some mechanical problems with your arrangement mostly. However, if you had a DC machine with a field winding instead of permanent magnet excitation, you can control the field strength. The stronger the field, the lower the speed for a given voltage The stronger the field, the higher the voltage for a given speed


1

You can easily get more output voltage from one motor driving a generator, the same as using an electronic voltage boosting circuit or using a transformer for AC. But the power cannot increase then the output current will be a little less than the input current. Are you thinking of Over Unity to feed the higher output voltage to power the original motor ...


4

It's true because the voltage is sinusoidal and sin(a).sin(b) = 1/2(cos(a-b)+cos(a+b)) And only in the case where a=b does the result have a mean value that is not zero. so all harmonics give a result that has no effect on the real power


6

From a sinewave grid, this is true since the harmonics are due to any "nonlinear device. For example, the partial magnetic core saturation controlled by the peak excitation voltage. However, that statement contradicts inexpensive inverters with square wave sources rated in V-rms. The harmonics in this voltage waveform can generate the same power in ...


28

It's an overly-general statement. Obviously, with a resistive load, all frequencies transfer power. It's really a statement about rotating machinery specifically (motors and generators). For these devices, energy at frequencies other than the fundamental is just as likely to oppose the work being done as aid it. Also, the energy of high frequencies is often ...


16

That is true only if the current is being distorted by the load and not due to distortion of the voltage waveform of the AC line. If you multiply the instantaneous values, point by point, of two sine waves of different frequencies, you get a waveform that has an average of zero. You have positive power during some intervals and negative power in other ...


0

The only reason you'd add a larger than 100 uF cap before the 2576 (or any DC DC converter) is for a smaller source you're pulling current from (I.e. an Alkaloid battery pack). As you pull more current to load the voltage goes down which could turn off the 2576, so you want to be sure the voltage is stabilized, so you add a big capacitor (470+ uF, ideally ...


2

One of the big benefits of AC mains power is that it can be transformed quite easily. Just about every device that connects to your wall socket has a transformer of some variety. A transformer does a couple of neat things for you. Firstly, it lets you change the voltage to the level you want and secondly it isolates your circuit from the mains wiring. Now ...


17

No, the maximum voltage of the LM2576 is 45V. There are also a few other problems with the schematic above: - You need to have an isolation transformer on AC mains for safety purposes - AC mains can have spikes over 400V, from lightning or other devices. You need protection from these spikes. - AC mains should be fused, so in the event of a fault, it ...


5

Nice try but this is DC-DC converter only and 40 or 60V max options. Keep mind AC line can have 120Vrms +/-10% or +/-170 Vpk sine This means even if you had a huge 200V cap it has to be charged up in zero time at some random voltage. All caps have internal effective series resistance or ESR so using Ohm's Law with say 1 Ohm ESR you can expect a 170A ...


2

Flicker: as dimmed, the LEDs have longer dark time than with full light. The light from the fluorescent material decays more. The human eye can well see the flicker, at least if the LED is a little aside from the center of the field of the vision. It has been the same with fluorescent lights and old CRT televisions. Another thing: If you have another non-...


12

The first waveform looks fine for mains, it can get much worse. I suggest you use a rent a power corruptor, or use a lab with an operator, to see how vulnerable your dimmer is. And work with those results to improve the design of the phase angle dimmer.


7

The distortion is due to diode rectifiers, phase angle rectifiers. The distortion is not such big that should cause any malfunction. Possibly, the LED power supply misinterprets these false glitches with expected phase angle voltage from the dimmer.


0

It will probably work well. You have to detect zero cross and then fire the triac. Alternative method is to use an analog circuit as U2008B, then use PWM and optocopler for the speed setpoint.


0

I found many example on the internet where people use the same method to control light bulbs and heaters Will this way work with universal motors (that has brushes)? If not what is the best way for that ? Its fine because its basically the same thing a SSR (solid state relay) does. Due to the inductive kick, the triac should have an inductive snubber ...


0

Yes, you can use a triac and a phase control circuit. However, some driving circuits may not work well for an inductive load. The gate current needs to persist long enough for the current to start flowing in the anode. Some driving circuits just use a narrow pulse, which will latch the triac for resistive loads, but can have issues with inductive loads.


0

A phase control circuit is the simplest way to provide reasonably good speed control for a universal motor. Controlled rectifier control would probably be a little better than TRIAC control. A full-wave rectifier with a PWM control could also be used. That would probably be a little better than a controlled rectifier. How much difference there is between one ...


1

the switch is not electrically connected to the socket and fuse. it also looks like those pins are on the back of the switch. It's probably isolated and non-isolated switch illumination. the data-sheet will say for sure.


0

Stealing the maths in a comment by Transistor, You're going to need a battery that can deliver about 42A. An 18Ah lead acid or other rechargeable battery may do that for a few minutes only. You also need an inverter than can supply 400W, and probably a short term surge rating above that. Check the rating on your inverter. If it cost $10, it's unlikely to ...


0

Practically, this is going to draw less than a few mA from the batteries and then steps the voltage up to the 150V so there's not going to be much remaining current capacity which is why the people who market it feel they can get away with it. When I worked with EL wire I trusted the wire plenty, but stayed clear of the connector when the device was on. You ...


0

1 uF is not like a voltage source, rather it is -j362 Ohms impedance at 440 Hz. The DAC sees an impedance of 1k - j362 and your cap sees 3.5V + an apparent AC voltage drop from 1.5V. It does not exceed the applied voltage. The important factor is to choose C and R load such that it is much greater than the DAC driver output impedance and C such that it’...


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