Recent content by unplebeian

  1. U

    I Question on the Lorentz force: Why is the force not F=q(v×B) = F=qv×qB

    Thank you, Dan. I thought about it graphically and it's evident that the scalar multiplication to both vectors prior to the cross product operation is incorrect. Rather take the cross product and then perform the scalar multiplication or simply any one vector like you suggested. Thank you.
  2. U

    I Question on the Lorentz force: Why is the force not F=q(v×B) = F=qv×qB

    Hi, Dan, I'm sorry I didn't get it. That is a scalar multiplication so q should be multiplied to both. Generally a(bxc)= abxac. Why are we multiplying only once?
  3. U

    I Question on the Lorentz force: Why is the force not F=q(v×B) = F=qv×qB

    Background: is the equation of Lorentz force for the force acting on a moving charge in electric and magnetic field. For the magnetic field only it is : F=qv×B. Question: For magnetic field only why is the force not F=q(v×B) = F=qv×qB
  4. U

    Interpreting SPI Commands in FPGA Applications

    Hi Joshy, I understand the protocol itself but I am still uncertain about what the next step is. I understand that the FPGA can capture the MOSI data on the clock edge (depending on the SPI mode). Let me give you an example. Let's say we want to write the data from reg 0x5 using the SPI...
  5. U

    Interpreting SPI Commands in FPGA Applications

    Hi folks, Can someone explain to me how an FPGA executes an I2C/SPI/other command written to it. I understand that there is an I2C_RX or a SPI_RX module that acts as a slave and can get the transmitted data. But shouldn't there be another interpreter that deciphers the data and takes action...
  6. U

    Need explanation about magnetic forces

    Thanks. That makes a lot of sense and also explains why an initial nudge is required to start the mechanism that propels the magnet all the way to the other end.
  7. U

    Need explanation about magnetic forces

    Hi, I saw this video and I can't explain why the magnet is propelled to the end of the coil with such a huge force. Can someone explain it in clear terms. I also tried to use Flemings left hand (or right hand) rule but it did not give me a satisfactory answer. Thanks, SM
  8. U

    How does a spectrum analyzer measure Noise Spectral Density

    Hi, I'm a noob when is comes to these kinds of measurements on a spectrum analyzer. Take for example two LDOs: 1. http://www.analog.com/media/en/technical-documentation/data-sheets/ADM7154.pdf 2. http://www.ti.com/lit/ds/symlink/lp5907.pdf (see figure 17) They claim...
  9. U

    Is Living Next to a Wifi Antenna Dangerous? Exploring the Risks and Realities

    Here is a good article on a website that adds more detail. A good read. http://www.antenna-theory.com/tutorial/cancer/cellphone.php
  10. U

    State space vs classical control

    I think the conversation is getting a bit out of control...no pun intended. Thank you, all, for your feedback (again no pun intended) and comments. They were very helpful. Clearly one method over another has it's superior points at a cost. Somewhere the discussion even went in the direct of a...
  11. U

    State space vs classical control

    Thank you, all for the comments and replies. So is this a correct way of thinking about state space: It is superior as there is a gain applied to each state variable so during a dynamic test, say step change in reference or during tracking, each state variable will be changed/adjusted...
  12. U

    State space vs classical control

    Hello, I have a fundamental question about why state space control techniques are superior to the classical methods. I l know that you can control a system with multiple inputs and outputs for several states using state space control, however, can't the same thing be done in classical control...
  13. U

    Diode Equation and Saturation Current

    Because most of the current is in the forward direction and the reverse current, due to the minority carriers, is low. Typically in the order of nA to uA.
  14. U

    PFC Offline Converters -- SEPIC, Cuk, Boundary Conduction Mode Flybacks

    Hi Berkeman, It is surprising that you need PFC for something as low as 25W. As far as I know, EU mandates PFC for powers >= 70W (or was it 75W)? The other question is do you need isolation or not. If not, then use a standard Boost PFC in DCM which will be well suited for this application and...
  15. U

    How can I generate a negative supply voltage for an Opamp?

    Hi, You need a lab DC source and two to be exact which you can get on ebay. You can construct your own, but that is a project in itself, so you're better on buying a dual source one of which you can connect in a opposite manner to create the negative rail. Alternately you can connect the...
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