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Type: Posts; User: treez

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  1. Closed: Resistance of component bag made of "reddish" ESD plastic?

    Hi
    Due to lack of funds we are doing electronics in an office with a carpet which is not ESD safe.
    Often we need to carry a PCB with ICs etc on it….walking across the carpet as we do so.
    The...
  2. Closed: Re: Non isolated SMPS does not need Y capacitors?

    Hi,
    Regarding an SMPS with just a two wire feed (go and return), it is a fact that generally a non-isolated design will give a lesser common mode noise problem than an isolated design.
    Why is this...
  3. Closed: Re: Non isolated SMPS does not need Y capacitors?

    Thanks, ..it would be too heavy to have an extra earth wire in the tether, along with the go and return wires.
  4. Closed: Re: Transient testing rig for 3720W power supply with DCDC modules.

    Thanks, though they wish to do it with a high side fet, more on this later.

    Do you agree that the switched FETs must have gate_source resistors for ESD and Damping reasons?...
    Our contractor...
  5. Replies
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    467

    Closed: Re: UC3845 ETD29 transformer PWM signal

    As Easy Peasy says you may well have blown the fet...and with a mains circuit and a blown fet...you may have blown the uc3845 too...a blown fet often goes short drain to gate...so your uc38xx may...
  6. Closed: Re: Large numbers of paralleled DCDC modules?...more than datasheet recomends

    This “noisy output current feature”….is possibly not a bad thing….the module still supplies the load perfectly well with max/off transients served very well.
    Also, I have just put 12mF of C(out)...
  7. Closed: Re: Large numbers of paralleled DCDC modules?...more than datasheet recomends

    ..I must admit this noise in the output current is the most unthreatening noise i have ever seen...it doesn't get any worse no matter how much extra c(out) is added.....it is always bounded to +8%...
  8. Closed: Re: Large numbers of paralleled DCDC modules?...more than datasheet recomends

    Hi,
    We find that when we have more than 220uF of C(out) on our DCDC module the output current gets unstable as attached.
    It’s a DCM3623T50M53C2T00.
    The Eval board for this module only has 220uF....
  9. Closed: Re: Noise coupling into DCDC module via the ground copper pour directly beneath it?

    The noise in the output current is solved by reducing the output capacitance to 220uF.
    -But the datasheet states that up to 2mF should be allowable at the output...so we are surprised we get noise...
  10. Closed: Re: How to mitigate large area ground current loops in large arrays of paralleled SMP

    Thanks, ...someone who says they have worked with these modules and systems before has assured us that our biggest problem will be "circulating currents".
    They wouldnt elaborate on exactly what...
  11. Closed: How to mitigate large area ground current loops in large arrays of paralleled SMPS's?

    Hi
    We are doing a 12kW power supply by paralleling over 40 DCDC modules. This question is not specifically about the modules. It is rather about the nature of “circulating currents” in such large...
  12. Closed: Re: Non isolated SMPS does not need Y capacitors?

    Please consider this riddle of common mode filtering in a non isolated SMPS...

    We have a non-isolated SMPS in a metal box, where chassis (metal box) ground and all the heatsinks are directly...
  13. Closed: Noise coupling into DCDC module via the ground copper pour directly beneath it?

    Hi,
    Please assist in telling if noise could be coupling into our DCDC module via the ground plane that we have underneath the module? Maybe we should remove the ground plane under the Vicor...
  14. Closed: Re: Non isolated SMPS does not need Y capacitors?

    Thanks, the drone won't have a real earth on it as such...the drone will be at the end of a 100 metre tether...this just comprises the go and return from the 700vdc power supply thats on the ground....
  15. Closed: Re: Non isolated SMPS does not need Y capacitors?

    the chassis cannot be grounded to the circuit negative, otherwise it will become a circuit conductor

    Base unit on ground is ultimately powered by an AC mains generator

    No we cannot connect...
  16. Closed: Re: Non isolated SMPS does not need Y capacitors?

    Thanks, and rather than regulations being the guide here.... it all follows from the fact that the metal chassis of the power supply, ..

    1...can't be allowed to float (otherwise if could get...
  17. Closed: Re: Non isolated SMPS does not need Y capacitors?

    Thanks, on page 87 of the DCM design guide, it shows chassis ground in yellow. Chassis ground is deliberately not connected to any circuit ground (neither primary or secondary ground). This I...
  18. Closed: Re: Non isolated SMPS does not need Y capacitors?

    We quite literally have nothing to connect Y capacitors to...so cannot use them. Would you agree?

    - - - Updated - - -
    ...
  19. Closed: Non isolated SMPS does not need Y capacitors?

    Hi,
    We are doing a non isolated SMPS so please confirm we don’t need Y capacitors in our common mode filter?

    Vin = 34V
    Vout = 48V
    Pout = 312W
    Incidentally, we are using the Vicor...
  20. Closed: Re: Transient testing rig for 3720W power supply with DCDC modules.

    Thanks, yes i'd prefer if it was non-retriggerable...but they are not as easy to source.
    Would you agree that in fact, it can actually be a re-triggerable one?...it just means the "One-shot" pulse...
  21. Closed: Re: thought experiment to understand measuring equipment.

    from your diagram, the meter will measure 60000 volts...i think you know this?
    There will be no current because an ideal voltmeter has no current flow....but a non-ideal one......
  22. Closed: Re: thought experiment to understand measuring equipment.

    ok but you dont have a circuit..and given an ideal multimeter it would say 0 volts
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    Closed: Re: how to make diy inverter

    19.5 volts and 3.34 amps sounds like 65w, ie low enough to not need power factor correction.
    So its probably just an offline flyback converter.
    So in this case, you would be best off just putting...
  24. Closed: Surely a signal should be filtered with a capacitor at the pin?

    Hi,
    We are using the DCM3623T50M53C2T00 as a DCDC module. This module has some signal pins. Its usual to provide noise-proofing for signal pins with a capacitor connected right at the pin....
  25. Closed: Re: Which type of SMD capacitors are more robust against PCB flexion cracking?

    Page 5 of the following indicates that “metal frame” ceramic caps are more resilient to both flexion cracking and solder cracking than “flexiterm” type ceramic caps. Would you agree with that?
    ...
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