Search:

Type: Posts; User: Easy peasy

Page 1 of 20 1 2 3 4

Search: Search took 0.02 seconds; generated 46 minute(s) ago.

  1. Replies
    16
    Views
    303

    Closed: Re: Wiring of DC fans in Series

    Q4 is not needed - Q3 will dissipate, Ifan * 15V so be careful there ...
  2. Closed: Re: Mains leaking currents causing problems in my house

    A PC psu should be designed to at least 2.5kV ac phase to o/p's if not it is a very bad PC to own

    a dish washer could be run thru an isolation Tx - but an electric cooker would...
  3. Closed: Re: Calculate Capacitance Value from Smith Chart

    he reactive part is 77.16 ohms, this is the sum of the Xc & XL, at 205MHz it is basically all capacitive so yes = Xc
  4. Replies
    6
    Views
    191

    Closed: Re: Buck converter vs buck-boost converter

    A flyback is also a buck-boost ( the original in fact )

    - - - Updated - - -

    as is a Sepic
  5. Replies
    16
    Views
    303

    Closed: Re: Wiring of DC fans in Series

    R's are fine - but extra power draw / loss and no guarantee of sharing at power up where fans can and do draw more than 5x the run current - and its pretty pulsed too...!

    - - - Updated - -...
  6. Closed: Re: Calculate Capacitance Value from Smith Chart

    the Smith chart is for a specific 10pF cap, that is clue #1, it is not explicitly shown on the Smith chart, but the 77 ohm at 205MHz gives you 10pF, presumably at very high freq the series L ...
  7. Closed: Re: Mains leaking currents causing problems in my house

    You could go around cutting out all the Y caps ( RFI caps that go from phase & neutral to "earth" ) inside the appliances that have them - this should stop you getting a boot off your PC - ...
  8. Replies
    16
    Views
    303

    Closed: Re: Wiring of DC fans in Series

    a 5W 16V zener across each fan will be the way to go, else a buck converter to 15V to run both of them in //.
  9. Closed: Re: Generation of 4 Phase Shifted clock Signals

    CMOS gate parts can do this easily @ 2.5MHZ look up the CD4000 series - there should be a shift register type part that will do it in 16 or 14 pins ...
  10. Replies
    6
    Views
    191

    Closed: Re: Buck converter vs buck-boost converter

    boost converter usually has low side drive to the fet which is easier, buck converter needs a level shift driver or a P channel fet - more parts will affect efficiency - but either can...
  11. Closed: Re: Calculate Capacitance Value from Smith Chart

    The smith chart for that cap shows you that at 205MHz it is 10pF ( 77 ohm ) and 50 ohm resistive ...
  12. Replies
    3
    Views
    171

    Closed: Re: Filter Cutoff Frequency

    the noise flows from right to left - ideally the CM caps need to be on the LHS ( left had side ) in order to get a CM LC filter - this can be undone if the primary mosfets are heatsunk to...
  13. Replies
    10
    Views
    609

    Closed: Re: Bridge diode thermal problem

    bigger caps = shorter current pulse = higher rms current draw = more heating in diodes and wires ...

    45V, 10A schottky a good idea if pk volts out of Tx are < 35V ... 5W zener...
  14. Closed: Re: How to calculate transformer winding losses

    Is a round-a-bout way of saying there are proximity losses in the copper wdgs associated with the windings - these losses are lower for higher coupling factor ( lower leakage )

    and are...
  15. Replies
    3
    Views
    155

    Closed: Re: Maintaining supply voltage on load

    better to have a pwm buck converter drive the heater from the batteries such that there are no sudden changes in the battery voltage

    OR: drive the fet with a 470k resistor such that it turns...
  16. Closed: Re: Closed-loop Stable for Negative Phase Margin?

    The bode blot requires that you consider the 1st crossing of the gain plot, not any later ones, if there is phase margin at the 1st crossing, it will be stable, later crossings can be ignored...
  17. Replies
    11
    Views
    520

    Closed: Re: Photocoupler Saturation?

    there is a fair chance your led will eventually die if subjected to unlimited current flow pulses ...

    opto's turn off slowly due to carriers stuck in the base region of the o/p xtor - faster ...
  18. Replies
    3
    Views
    276

    Closed: Re: H-bridge gate signal problem

    welcome to the world of RFI ...
  19. Closed: Re: Film capacitor failed in flyback smps at high temperature?

    hi temp = expansion of either type of cap = end termination failure = cap goes low capacitance ....
  20. Replies
    13
    Views
    1,037

    Closed: Re: HEI primary current duration

    certainly you will need soft turn off of the igbt to avoid a spark - if you are calculating dwell periods based on current rpm -
  21. Closed: Re: Why use diff mode inductors rated for 6A(rms) when Input current is only 833mA(rm

    depends on the size of transient you are required to resist - in avionics it could be quite important ...!
  22. Closed: Re: Supply 5V, 5mA from the 240VAC mains without SMPS

    those ckts are risky in that if the fet fails - the following ckts and any isolated wdg's on any comm's transformers go poof ...!
  23. Closed: Re: 300W SMPS with low input capacitance at the end of a 10km cable

    there are standard solutions for 1400V ( + safety margin ) to 60V - and 5 amps out is pretty easy - 1/2 bridge with cascaded devices ...
  24. Closed: Re: Supply 5V, 5mA from the 240VAC mains without SMPS

    yes the mosfet ( or igbt ) has volt and current limit - the big R is to limit the Pdiss of the device and act like a fuse if it goes short - 5W zener on Vout to ensure the fuse blows ... ...
  25. Closed: Re: Why use diff mode inductors rated for 6A(rms) when Input current is only 833mA(rm

    low heat dissipation, high transient capability, - they were in stock ...
Results 1 to 25 of 500
Page 1 of 20 1 2 3 4