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  1. Closed: Re: Is a snubber circuit required with zero-cross optocoupler

    A snubber is a good idea if the load is unknown, these drivers switch the triac on soon after zero crossing, so the load current will start from zero too ( although will go up quickly for some...
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    Closed: Re: Dimmer lamp 220v ac (resistor values)

    if you want to limit the max gate current to 1A say, then R1 + R2 = 325 ohm, note they must be rated for >200V each to avoid them breaking down ...
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    Closed: Re: UC3845 ETD29 transformer PWM signal

    Faulty scope probes or "open ckt" gnd connections will not help in fault finding, hopefully your fet and driver and associated cktry have survived and you can check the transformer phasing

    you...
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    Closed: Re: UC3845 ETD29 transformer PWM signal

    A flyback transformer needs a gap in the core ( unless for VERY low power ) to store the energy, It is essentially a well coupled inductor.

    With no gap the transformer will saturate ( Bpk ) and...
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    Closed: Re: UC3845 ETD29 transformer PWM signal

    the fet might well be dead ...

    - - - Updated - - -

    or the transformer phasing or gap may be wrong ...
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    Closed: Re: how to make diy inverter

    the above modified sine wave will power a lap top charger as will even cruder modified sine system of a single step - mainly because the laptop adapter has a bridge rectifier from which it operates...
  7. Closed: Re: thought experiment to understand measuring equipment.

    I think you guys have properly scared him off this thread/site now ...
  8. Closed: Re: Inductor question. Why current goes up then down instead of decreasing with frequ

    yes opposite effect described - apologies - either a typo or there is a series cap causing a min resonance in Z.
  9. Closed: Re: Inductor question. Why current goes up then down instead of decreasing with frequ

    You are seeing parallel resonance of the inductor - at a certain frequency it will look hi Z - it will then support all the volts from the source, at other frequencies it is lower Z and pulls...
  10. Closed: Re: Current sensor upstream of Bulk of output capacitance in DCDC converter?

    Some of your caps might be a bit iffy - this used to be a prime source of noise once - which was hard to find ...
  11. Closed: Re: Current sensor upstream of Bulk of output capacitance in DCDC converter?

    Yep - sure you can try that ...
  12. Closed: Re: Current sensor upstream of Bulk of output capacitance in DCDC converter?

    yes there is HF ripple of some sort flowing b/n the internal and external caps, upsetting your ( low cost (?)) I sensor - the only way to mitigate this is a choke on the o/p of the module then...
  13. Closed: Re: what if i connect a battery to the electromagnet?

    Depends on the Lithium chemistry, but most of the energy is delivered at 3V, a quality industrial Li-Fe-PO4 ( prismatic ) delivers from 3.3 to 2.9V

    the polymer ones have higher voltages...
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    [SOLVED]Closed: Re: uc3842/3843 Vcc problem in smps.

    it will cause a lot of extra primary current - a bad thing ... when the main mosfet has to turn off
  15. Closed: Re: what if i connect a battery to the electromagnet?

    Measure the resistance of your electromagnet if it is 0.5 ohm say ... at 3.0 volts this is 6A, your 18650 cell will not provide this for very long at all ...
  16. Closed: Re: thought experiment to understand radio propagation.

    it also depends on the effective radiated power - a usual receiver can operate on 0.5uV,
  17. Closed: Re: Current sensor upstream of Bulk of output capacitance in DCDC converter?

    Upstream means the sensor sees all the high freq current info into the capacitor - this will always be more stable ...
  18. Closed: Re: Question why one of the MOSFET burn shorted in my SS relay

    If, you are using fets from Ali-express - you need to allow that failures will happen ...
  19. Closed: Re: 250VAC, 4A fuse used at 700V input to SMPS?

    this is difference between knowledge gained through testing - and other noises ...
  20. Closed: Re: 250VAC, 4A fuse used at 700V input to SMPS?

    We have performed a lot of DC fuse testing - at 12kW, 700V the source is likely current limited, 20A or so, sand filled ceramic fuses will handle this well, of course 38mm ( x10) would...
  21. Closed: Re: 250VAC, 4A fuse used at 700V input to SMPS?

    Ceramic ( sand ) filled 20mm fuse will be fine - they are designed to handle a lot more than you expect ...
  22. [SOLVED]Closed: Re: Op amp testing question about feedback loop

    you need to look at the WHOLE circuit - not just the op-amp bit ...
  23. Closed: Re: how to measure permeability of iron core?

    Measure the inductance of the coil with and without the core present - the ratio of inductance is a fair measure of the relative permeability of the core - it needs to be a completely closed mag...
  24. Closed: Re: Full wave bridge rectifier but doing half wave

    use two scope probes and subtract them ( Ch1-Ch2 ) to see what is going on without shorting the 0v of the ckt ( cos the sig gen has an earthed o/p and so does the scope )

    no need to connect...
  25. Closed: Re: Question why one of the MOSFET burn shorted in my SS relay

    If we are to believe your earlier posts - you have already captured the G-S turn on - so it is difficult to see the issue here. As stated above set the rigger to +35V rising to capure the...
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