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  1. Replies
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    Closed: Re: LTSpice Noise Analyis

    Wait I have to take my last statement back. I simply screwed up the importing of the OPA140 model (symbol was still referencing an ideal model). So on a second quick look the OPA140 and a handful...
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    Closed: Re: LTSpice Noise Analyis

    Ok and part of my question is about realistic model expectations.

    For example TI's OPA140 has no noise when simulated in LTSpice's noise mode.

    Of course this is what I expected - performance...
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    Closed: Re: Optimally Accurate 28-bit A/D conversion

    Agree except I'd point out that the way this is handled is with ranging.

    It is possible to make a system with 180nV resolution that can also handle 3V full scale....just not at the same time.
  4. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    Agree with the regulator suggestion. 12V regulator or 9V regulator. If 12V is fed to a 12V regulator it should just saturate at its dropout voltage (~11.5V for example) and will work fine.

    ...
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    Closed: Re: How to "de-resonate" a resonant circuit?

    Clamp the inductor with a diode.

    Replace the resistor with a current source.

    Choose an inductor that saturates at low currents to limit resonant energy storage.


    Though you’re not clear...
  6. Closed: Re: PSIM Problem in a Basic Circuit (Unable to load psim.dll)

    I’ve used pain a lot and have never seen it.

    Restart, reinstall, contact tech support.
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    Closed: Re: How to instantiate a submodule in Verilog

    Yes its common thus worth me saying “It doesn’t have to be that way”.

    The software world has the same debate about classes and I think the right answer is the same: it makes sense sometimes.
    ...
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    Closed: Re: How to instantiate a submodule in Verilog

    Don't agree.

    I often find it preferable to leave multiple associated modules in a single file including the test-bench for that module.


    And it certainly isn't the cause of the problems here.
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    Closed: LTSpice Noise Analyis

    Does anyone understand how LTSpice's noise simulation works under the hood?

    I've used LTSpice extensively but barely touched the noise mode (I'm trying to catch up on my understanding of noise...
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    Closed: Re: input current of the integrator

    Yep that's exactly it.
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    Closed: Re: input current of the integrator

    Because keeping the + and - inputs equal (by sourcing or sinking output current/voltage) is the textbook behavior of an opamp.

    Though it has limits in its ability to do that (output current,...
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    Closed: Re: overvoltage protection

    If you need <5% variation in clamping voltage no 2 terminal off the shelf device is going to do it.

    They’re not a bad idea, and may be what you want, but understand they don’t have that kind of...
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    Closed: Re: 24Vdc Relay for a DC load of 2A 600V

    Low amp DC is a good candidate for solid state solutions, here is an example of something close:
    AQAD171DL


    This depletion fet is normally on. 2 in series back-to-back for AC blocking with a...
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    Closed: Re: input current of the integrator

    Understand that AC current is DC current until it switches direction. 50hz AC is DC for 10ms periods.

    So a cap is perfectly happy passing DC current...until its voltage as described by the...
  15. Closed: Re: Use an OR wired with diodes to control the gate in a PMOSFET

    You have some problems.

    The diodes prevent the NPN's from ever turning on the gate.

    Second you need a wired nand it seems:
    If all inputs are 0 -> good -> pull down gate -> turn on pfet
    If any...
  16. Closed: Re: Circuit to pulse from 1v to 1.1v repeatedly.

    Agree: just switch or mux the opamp reference.

    A second option is to mux two different sources. NLASB3157 is an example of SPDT analog mux.
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    Closed: Re: Linear led current regulator

    Sounds like you need this chip called an 'op-amp'....

    I mean what value-add do you want from the chip? You buy LED drivers because they provide all the things you specified are external.

    EDIT:...
  18. Closed: Re: Off the shelf inductor with 400V rating...for Offline Buckboost converter

    Nope. I've seen two off the shelf inductors that reference voltage ratings, one is the wurth series you linked and a second is a series from Pulse:
    ...
  19. Closed: Re: MOSFET linear and saturation region operation

    Eh my point is that once you wrap it with feedback the exact equations become irrelevant.

    And if you don't wrap it in feedback part variations mean you better not care about the exact relationship...
  20. Closed: Re: MOSFET linear and saturation region operation

    One question I have when someone understands this stuff is why?

    A mosftet goes from 'as off as it gets' -> partly on -> 'more on' -> 'mostly on' -> 'as on as it gets' as Vgs increases. But the...
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    Closed: Re: Differential probe build

    First, the suggestion is one series chain per input (positive and negative)



    [in+/-]
    |
    [1meg]
    |---------o
    [100k]
    |---------o o--------Amplifier + or -
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    Closed: Re: OpAmp BW for Feedback loop

    Have you run into any specific tradeoffs yet choosing amplifiers?

    I ask because for what I care about I don't see a lot of hard choices until about 10mhz and up. See OPA192 for example has low...
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    Closed: Re: Differential probe build

    For one because low C is a figure of merit for a scope probe. You don't want to load the circuit being measured. Have the lowest C possible.

    Second there is no reason you can't get the same...
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    Closed: Re: OpAmp BW for Feedback loop

    1) Both. There is guaranteed to be switching frequency noise. Best to oversample above it if possible and higher sample rate means less delay. Don’t forget that.
    2) General ADC good practice...
  25. Closed: Re: [Microcontroller] Voltage Reading without ADC

    Input voltage thresholds are very widely specified however. Perhaps adding 50% worst case error.

    Could be improved by adding a comparator with reference to the scheme.


    Another scheme is to...
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