Search results

Search Forums New Posts
  1. L

    Science Project BrainTeaser Question

    It doesn't seem so simple to me. Gotta hint?
  2. L

    Science Project BrainTeaser Question

    In the requirements as described it does not matter whether a switch is set to the left or to the right. For all combinations of switch settings (L-L, L-R, R-L, R-R) both lights are always on. Do you need to rephrase the problem? One way to make it work would be to construct each switch where...
  3. L

    Interfacing microprocessor and buckpuck LED driver

    So if I understand this correctly the problem only surfaces when the two BuckPuck Vin power terminals are connected in parallel to the same power supply. Also, note Figure 18 of the datasheet which shows a filter capacitor across the BuckPuck power terminals. This suggests that the SMPS places...
  4. L

    Interfacing microprocessor and buckpuck LED driver

    So given your schematic I surmise the BuckPucks are wired in parallel with the Vin+, Vin-, LED-, & REF pins connected together. If that is the case, then the wisdom of connecting the REF pins together is suspect. For troubleshooting try removing the micro-controller and getting it to work with...
  5. L

    periodic function foureir transform in practice

    You asked, "how do i look at this in reality?" What if the instrument you were using in the lab was designed to take a sine wave of amplitude 'A' and display its Fourier spectrum with an amplitude of 'A'? That would be my reality.
  6. L

    periodic function foureir transform in practice

    If you are looking at power in the Fourier transform, Parseval's theorem relates energy in the time domain to energy in the frequency domain. But getting energy in the frequency domain requires integrating the square of the Fourier transform, which for this signal means squaring the Dirac delta...
  7. L

    voltage peaks&time constant for inductor for square wave

    The inductor only acts like a short circuit beginning about 5 LR time constants past a transient event. At the beginning of a transient event the inductor resists any change in the current flowing through it. That is why you can model the inductor as an open circuit when the transistor switch...
  8. L

    1st year help please

    So have you calculated the reactance (X) for the L and C components? That would be a good place to start. Then the impedance of each leg would be Z1=R1+X1, Z2=R2+X2. I1=V/Z1 and I2=V/Z2. So I1 and I2 are each phasor currents with I=I1+I2. Does that suggest a phasor diagram to find I? In...
  9. L

    Skin effect in 1 milliOhm resistor?

    Wikipedia gives a formula for skin depth as a function of the frequency, relative permeability and resistivity of the medium. It is likely that the relative permeability of the material comprising the sense resistor is 1, while the resitivity is somewhat higher than copper. A high restivity...
  10. L

    Ohm's Law Conundrum

    Look at your circuit and determine whether the current flows from a current source or a voltage source. If the current comes from a current source, then the current will be constant and the voltage will change with the resistance. If the current comes from a voltage source, which is the usual...
  11. L

    Induction Heating

    See ST Microelectronics Application Note AN2383 "A single plate induction cooker with the ST7FLITE09Y0" http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00115561.pdf
  12. L

    Frequency Response

    You may need to review the basics of complex arithmetic, particularly the process of finding the magnitude of a complex number using multiplication with the complex conjugate of the number.
  13. L

    Frequency Response

    See the attachment which confirms that the book answer is correct for the cutoff frequency of 25K radians. Note that cutoff and corner frequency are the same thing for a low pass or a high pass filter. However the center frequency is something quite different. I usually prefer to work...
  14. L

    What if this happened?(theoretically )

    When the generated back-EMF equals the applied EMF there would be no current flow, hence no torque produced by the motor. With no torque the motor slows down, producing less B-EMF so that more current flows. But with a stronger magnetic field the same B-EMF will be produced at a slower RPM.
  15. L

    Non-integrating low pass filter

    At the 3 uV signal level there will be a certain signal to noise ratio, whatever it is. If that 3 uV signal is amplified to 300 uV without adding additional noise, then the 300 uV signal has the same SNR. Now suppose there is some further signal processing that adds 5 uV of noise. That added...
  16. L

    Non-integrating low pass filter

    Medical equipment has stringent requirements to provide galvanic isolation from the patient into the kilovolt range for both powerline faults and electrostatic discharge. This is the first requirement, above all other considerations. EEG signals from any point on the scalp are just a few...
  17. L

    EM wave question

    The only active consideration of wireless power transmission that I am aware of is for space-based solar power where a gigantic solar power satellite in geosynchronous orbit collects energy for transmission back to earth in a focused microwave beam to a huge antenna field where a rectanna...
  18. L

    Switched capacitor op-amp

    Have a look at the Anadigm AN120E04 Reconfigurable FPAA which consists of a 2 x 2 matrix of fully configurable switched capacitor configurable analog blocks (CABs), enmeshed in a fabric of programmable interconnect resources. One part of each CAB is a bank of 8 programmable capacitors. Each of...
  19. L

    For what value of L, will this circuit resonate at 332kHz?

    This was an interesting circuit to analyze, forcing one to learn new techniques for dealing with complicated equations. It was necessary to assume that the 0.1 uF capacitors provided a direct path to RF signal ground so that the C11, C66, & R11 components could be removed from the circuit. As...
  20. L

    Low-High Pass Filter

    A first-order filter will comprise a single resistor and single capacitor. Nothing more complex seems to be necessary here. Don't know what Q#2 is supposed to mean, possibly since I don't know what sinusoidal outputs are available.
Top