# Search results

1. ### A more efficient transformer

None of the above. The idea is to remove the back emf from the secondary to the primary. The result of doing this is to reduce, if not cancel, the increase in amperage draw from the source due to the load on the secondary. Effectively the source only has to supply enough current to maintain the...
2. ### A more efficient transformer

Surely if you only have to maintain the magnetizing current that creates the magnetic flux that has to be efficient.
3. ### A more efficient transformer

Well think of a capital 'E' turned on its side with a connecting piece across the top. The primary coil is wound on the center leg and the secondaries wound on the two end legs. This transformer would only work one way.
4. ### A more efficient transformer

I have been reading about mag-amps which gave me an idea for a more efficient transformer. So the core is in the shape of a square or rectangle with a center piece dividing it into two. The construction of the outer core is larger (less reluctance) than the middle leg (greater reluctance). The...
5. ### Capacitor Voltage

The charging path is what I am interested in. Your right - I don't understand the circuits operation.
6. ### Capacitor Voltage

dVc/dt = VpSin(ωt)*1/RC*e-t/RC+(1-e-t/RC)*Vp*ω*Cos(ωt) Don't ask me to plug values into that or graph it. I've already tried and can't get anything to either calculate a result or graph it.
7. ### Capacitor Voltage

Hi, I am trying to figure out the peak voltage across a capacitor when charged by 1/2 wave rectified AC. The formula for instantaneous voltage is : Vc=Vs(1-e-t/RC) where: Vc=Capacitor voltage, Vs=Source Voltage, t=time RC = the capacitor time constant So I thought I could integrate with...
8. ### Energy in a capacitor

This post is inspired by a lesson on the allaboutcircuits education website. In chapter 15 of Direct Current there is a heading "Inductors and Calculus" - https://www.allaboutcircuits.com/textbook/direct-current/chpt-15/inductors-and-calculus/ At the bottom of the topic there is a circuit...
9. ### Plasma Multipactor

I have been reading a patent by Gene Meeks of a plasma multipactor. Meeks was the right hand man of Philo Farnsworth the "father of television" and worked with him on the 'fusor' - a small nuclear fusion device. Meeks's multipactor appears to be a self sustaining over unity power device...
10. ### Independent Component Analysis vs Single Spectrum Analysis

Homework Statement Hello, I have implemented single spectrum analysis and independent component analysis against a time series (in this case the euro foreign exchange) as a smoothing indicator. The ssa algorithm I purchased from: Caterpillar-SSA - http://www.gistatgroup.com/cat/programs.html...
11. ### Single Channel Blind Source Seperation

Homework Statement I am trying to figure out how to do independent component analysis on a single stream of time series data. The ica algorithm comes as part of the it++ package however it is necessary to perform some preprocessing on the time series data as ica works on the premise that the...
12. ### The mean of the Probability Density Function

Thanks guys. I've done some more reading and investigation. Rather than the mean I prefer to think of it as "expected value".

18. ### Derivative of Dirac Delta - Fourier Transform - Time Differentitation Property

Homework Statement I am using the time differentiation property to find the fourier transform of the following function: Homework Equations f(t)=2r(t)-2r(t-1)-2u(t-2) The Attempt at a Solution f'(t)=2u(t)-2u(t-1)-2δ(t-2) f''(t)=2δ(t)-2δ(t-1)-??????? Can somebody explain what...
19. ### Properties of the Fourier Transform - Time Differentitation

Thanks marcusl. I see now.
20. ### Properties of the Fourier Transform - Time Differentitation

Homework Statement This is copied from a book: \eqalign{ & {\rm{Time Differentitation}} \cr & {\rm{Given that: }}F(\omega ) = F\left[ {f(t)} \right] \cr & F\left[ {f'(t)} \right] = jwF(\omega ) \cr & {\rm{Proof:}} \cr & f(t) = {F^{ - 1}}\left[ {F\left( \omega \right)}...
21. ### Difference between and odd symmetrical function and 1/2 wave odd symmetrical function

I agree. The surest method is to just go with the formal definition.
22. ### Difference between and odd symmetrical function and 1/2 wave odd symmetrical function

Homework Statement The book defines a 1/2 wave odd symmetrical function as each 1/2 cycle is a mirror image of the next. \begin{array}{l} {a_0} = 0 \\ {a_n} = {\textstyle{4 \over T}}\int_0^{{\raise0.5ex\hbox{$\scriptstyle T$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{\$\scriptstyle...
23. ### [cos nt - n.sin nt] rewrite as [cos (nt + tan^-1 n)]

I see what is going on now.
24. ### [cos nt - n.sin nt] rewrite as [cos (nt + tan^-1 n)]

Homework Statement I am working through an example in fourier analysis and the author has rewritten [cos nt - n*sin nt] as [cos (nt + tan^-1 n)]. Can somebody show how he does this? ie. the steps involved. Homework Equations The Attempt at a Solution
25. ### Laplace Transform

True - it isn't that tough. But I am not so keen on integration by parts if I can avoid it. Thanks for the reply.
26. ### Laplace Transform

Homework Statement Is there an easier way of solving this rather than doing the integral? Find the laplace transform of: t{e^{ - t}}u(t - 1) Homework Equations The Attempt at a Solution \int_1^\infty {t{e^{ - t}}} {e^{ - st}}dt = \int_1^\infty {t{e^{ - t(1 + s)}}} dt =...
27. ### Derivative of an Integral

Leibniz's Integral rule as shown by Dick does the trick: \frac{d}{{ds}}\int_0^\infty {f\left( t \right){e^{ - st}}dt} = \int_0^\infty {\frac{\delta }{{\delta s}}f\left( t \right){e^{ - st}}dt} = \int_0^\infty {f\left( t \right)\left( { - t{e^{ - st}}} \right)dt} = \int_0^\infty { -...
28. ### Derivative of an Integral

Homework Statement F is an antiderivative of f, so F’=f. \begin{array}{l} \int_{g(x)}^{h(x)} {f(t)\,dt} = F\left( {h\left( x \right)} \right) - F\left( {g\left( x \right)} \right) \\ \frac{d}{{dx}}\int_{g(x)}^{h(x)} {f(t)\,dt} = F'\left( {h\left( x \right)} \right)h'\left( x \right) -...
29. ### Energy in AC circuits

That's what I thought until I read this: http://amasci.com/miscon/whatis2.html#2 The guy says he is an electrical engineer so I figured he must know what he is talking about. Seems to make sense as the electrons in AC electricity are simply vibrating inplace. As I understand it a vibrating...
30. ### Energy in AC circuits

Given that: E = hν where E = energy of a photon h = Planck's constant = 6.626 x 10-34 J·s ν = frequency Why is it that the energy (electromagnetic waves) in AC electrical circuits does not include frequency as part of the formula? eg. \begin{array}{l} P =...