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  1. Closed: Re: Opinions about SEPIC versus Zeta converters

    another newbie oversight - when the fet turns on there is an enormous current pulse as it shorts out the blocking cap via the diode that shouldn't be there ... and discharges it to zero every...
  2. Closed: Re: Opinions about SEPIC versus Zeta converters

    your ckt is missing a choke - has diode instead ...?
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    Closed: Re: Transformer coupled Class A amplifier

    No - it is just the fact that once the xtor has turned on, i.e. output goes low, you have stored an amount of energy in the xfmr core, now if the xtor is turned off above a certain rate its...
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    Closed: Re: 2n7000 ON resistance

    Neazoi, post a link to the data sheet to make it easier for people to point out the relevant bits for Rds-on at Vgs = 5V & 200mA ...
  5. Closed: Re: High side mosfet driver blows up. help :)

    Sigh, 1uF MLCC pin 8-6, AND ... R2 = 6R8 ...

    AND R3 = 10 ohms,
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    Closed: Re: EP13 transformer core looks open

    it is a closed mag path - just look harder ....
  7. Closed: Re: Opinions about SEPIC versus Zeta converters

    We have built Sepics to 350kHz, choose Sepic when you want low input ripple ( and can have a quality o/p cap )

    Zeta ( or inverse Sepic ) when you need a low o/p cap, and can handle the...
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    Closed: Re: HUM in transmitter PSU

    laptop psu's do make a lot of CM noise ...
  9. Closed: Re: Determining Value of Capacitor Between PV Panel and DC-DC Convertor.

    Hello Brad, um, where do you get the 0.5 amps from ... ?
  10. Closed: Re: Dont need a super accurate, super high bandwidth In Amp...

    LM324 / 358 ( same IC but pair / quad ) would be fine for this ...
  11. Closed: Re: Determining Value of Capacitor Between PV Panel and DC-DC Convertor.

    If in doubt, put 1000 - 2200uF at 1.5 x max input volts on the input to the converter - hopefully it runs MPPT so that it's output will reduce along with the inicdent sunlight - else it...
  12. Closed: Re: Problem with current loss with increasing length of wire

    keep doubling up or tripling up the wires .....
  13. Closed: Re: Dont need a super accurate, super high bandwidth In Amp...

    Brian's idea will work but need needs a split supply for the op-amp - unless you offset each input from the ( accurate ) 5V supply ...
  14. Closed: Re: Relative Robustness of power semiconductors (generally)

    SCR is the one that can handle the highest current peak, but it has a di/dt limitation at turn on - so series L needed

    IGBT driven at 7 volts gate is also quite rugged due to self current...
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    Closed: Re: Ferrite Core Size Selection Method

    " trial " process can be done with paper, pencil & calculator, iterating on paper gets you a lot closer to a real transformer that won't overheat ...
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    Closed: Re: Ferrite Core Size Selection Method

    The methods are in fact exactly the same with some fudge factors built in for wdg fill factor for the "formula" approach, same as my method, except with my method you get to see exactly what you...
  17. Closed: Re: Uplight dimmer based on phase-fired controller: Noise Issue

    your: www.uhu.com/en/product-page/plus-endfest/3950

    is worth a try - get plenty on - esp around all the wires .... on the core ... heat the whole thing to 35 deg C to aid the flow of the...
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    Closed: Re: 100uA analogue meter conversion to 1A?

    how to measure: 1.5V cell or power supply, 10k pot wired as rheostat, put in series with the meter, wind rheostat down to min while observing meter, when at FSD, measure volts across coil, ...
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    Closed: Re: Superheterodyne Receiver

    The IF is tuned so that the difference freq is the one of interest, 455kHz for the AM band

    for 88-108 FM the IF can be tuned over the same range to get the PLL to generate the audio directly ...
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    Closed: Re: Ferrite Core Size Selection Method

    All methods end up being iterative - as judgement is needed as to freq and Bpk, and cooling available ....

    At 100kHz, a Bpk of 100mT ( each way ) is a good starting point, depending on the...
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    Closed: Re: 100uA analogue meter conversion to 1A?

    If we assume your 100uA meter is 100 ohm R, then this gives 10mV to drive it to 100uA and full scale

    therefore to measure 1A, we need a shunt resistor of 10mV / 1A = 10 milli-ohm ( ...
  22. Closed: Re: Uplight dimmer based on phase-fired controller: Noise Issue

    "SCR talk" is also a feature of large SCR installations due to the rise time of current in the devices

    potting with "araldite" or similar 2 part potting goo or transformer varnish may well...
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    Closed: Re: TL494 Doubts about driving NPNs

    both schematics displayed appear to be "ünreliable" shall we say ...
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    Closed: Re: TL494 Doubts about driving NPNs

    the ckt is a bit wrong as the pull up R's to the pus-pull gate drive xfmr are not symmetric and one resistor has no value....
  25. Closed: Re: Trying to find a greater than 240v ac source on 150w 12v dc to 240v ac car invert

    100 VA is 263mA on the 380V tapping if this is enough then yes, if you need more then ask for more

    you have a 200W inverter, so 200VA would be a match to that ( 230V, 870mA in, ...
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