Search results

  1. I

    Inductor in LC filter

    The amount of current and frequency has a lot to do with selecting the proper core shape (for cross sectional area) and material (for Bsat). How much ripple current can yo live with? You can get toriods in soft ferrite material now and the "Cool-Mu" toriods from Magnetics work very well in SMPS.
  2. I

    5 volt to 3.3 volt

    Audioguru Before I reply, please give me your definition of “static and dynamic” circuit behavior, and into which catagory you feel this particular circiut falls. Again, the 3.3V is being derived from a regulated 5V.
  3. I

    5 volt to 3.3 volt

    This is a static type application (regulated 5V to 3.3V), so exactly how does a 6.8V zener regulate 11.5 times better than 3.3V zener? Please explain why you think "dynamic impedance " comes into consideration here? The magic number is 5.1V for a zero temperature coefficient. The series diode...
  4. I

    pulse waveform

    I would think more like 400Hz (F=1/(5*.5ms).
  5. I

    Highside mosfet gate spike

    In your simulation, the M6 gate signal is referenced to gnd. The only thing that matters is Vgs, so you have to use the M6 source as a reference when looking at whats going on at it's gate. PNP MOSFET's?? Do you mean P channel? Electric golf carts use regenerative braking for "braking" and...
  6. I

    Highside mosfet gate spike

    Hmmmm... If M7 is on all the time and you turn on M5, you are shorting the motor... is this what you wanted? There also doesn't appear to be a "flywheel" device across the motor. You could put a clamp zener on the gates to "limit" the spike or you could try snubbers across M6 & M5. Have you...
  7. I

    Highside mosfet gate spike

    MrHeckles
  8. I

    opamp phase compensation

    Applying a high frequency signal to an opamp circuit doesn't change the circuits phase shift. Opamp "compensation circuits" change/alter the gain/bandwidth of the circuit and is fixed... the poles and zeros that the compensation circuit introduces don't move around just because you change the...
  9. I

    How this switch working?

    It is a flyback converter. The secondary, with the polarity as shown will go negative to the collector of the transistor. The resistor is used to turn off the transistor when the breaker opens. It value isn't critical, but you can waste a lot of power if you make it's value to low.
  10. I

    Quick questions about transformers

    That formula isn't "exactly" true. To keep the math simple, consider i=C*dv/dt. Rearrange the terms... (i*t)/C=dv  This tells you that for a given capacitor  of value "C", drawing "i" amps for "t" seconds will result in a voltage dip of "dv". If a square wave was charging the capacitor, the...
  11. I

    Whats a switching diode?

    This is a little misleading in that ALL diodes exhibit this phenomena, forward bias-on, reverse bias-off, not just switching diodes... the "switching" part of the name refers to speed as it relates to reverse recovery, not it's "action"!! There are also diode's which exhibit a "soft" reverse...
  12. I

    Convert 0-30V 3A PSU to 5A or more

    The moderator is not wrong!! There are cases where you do want to do this, but IT IS NOT nessessary everywhere!! Guru... how exactly do values in the range of 10,000uF and RF go "together"??
  13. I

    Convert 0-30V 3A PSU to 5A or more

    Actually it is better because the ESR will be lower with parallel caps. Who would use a capacitor of that value at those frequencies???
  14. I

    AWG (American Wire Gauge)

    1000 mils is an inch mils are not mm 1 mil is .001" As I recall, .0014" (1.4mils) is 1oz Cu... so 2oz Cu is 2.8mils... etc
  15. I

    How this regulator works?

    As the 431 starts to draw current through R72 it will start to turn on Q13 which will load the 3.3V output in the event "it" has a light load and hold the output within load regulation limits.
  16. I

    85C Cap ESR vs 105C Cap ESR!

    It really depends on the application. This is true, but you have to use the RMS value of the ripple current, something that is not always easy to calculate or measure. Sometimes you want ESR to be high, sometimes you want it to be low. For example... in a SMPS, the input filter likes a higher...
  17. I

    DIODE QUERY

    If you "short" a diode, it will never "turn on". If it never turns on, no current will flow through it and all the current will flow through the short. In other words, no the diode will not be destroyed.
  18. I

    50Hz when you touch Oscilloscope probe

    As I said... try this with a battery operated/powered scope this will give you a clue!!!
  19. I

    50Hz when you touch Oscilloscope probe

    I believe the answer is "leakage current" in conjuntion with a capacitive divider (as mentioned above). If your hands are moist, touch the tip of the scope probe with one hand and the scope ground wire between two fingers with the other hand. Squeeze the ground wire harder between your fingers...
  20. I

    indulis or Audioguru?

    How does one select the type of power supply and or topology to use when designing a power supply? Should it be continuous, discontinuous, isolated, non-isolated, voltage mode, current mode, forward, flyback, Cuk, synchronous, non-synchronous, etc., or not even a SMPS at all and a linear...
Top