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Type: Posts; User: KlausST

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  1. Closed: Re: Minimum switching current for Mechanical switch

    Hi,

    You say it is 10mA "minimum" switching current. But you treat it as "maximum".
    I doubt that 10mA is the "maximum allowed" switching current - but it may be possible.

    Best if you post a...
  2. Replies
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    226

    Closed: Re: ADC output bit rate and PCB layout

    Hi,

    Since you have two data per clock period (one per edge): DCO of 455MHz gives 910MBPS.
    --> low margin.

    Klaus
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    Closed: Re: BLDC motor delta winding

    Hi,


    For sure.
    Your control unit is not able to decide whether the load is in delta or star connection (besides the magnitude of the current)

    Klaus
  4. Closed: Re: Passing both DC and pulses through a toroid?

    Hi,


    I know what you mean.

    Just to be more exact:
    * DC means infinite time.
    * If time is finite ... better talk about a "pulse"

    And even such a pulse needs to be a "single" pulse... at...
  5. Closed: Re: Passing both DC and pulses through a toroid?

    Hi,


    YES, but only theoretically with an infinite big core.
    NO, for real transformers.

    The bigger the core, the lower the frequency you may pass from primary to secondary.
    But low frequency...
  6. Closed: Re: Passing both DC and pulses through a toroid?

    Hi,

    I agree with asdf44.

    You have contradicting requirements:
    * applying DC
    * non saturating
    * no output

    If you apply DC... then there will be output.
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    Closed: Re: stm32f103 update frimware from spiflash

    ...sorry for the wrong order of posts
    ***************************

    Hi,

    Again: We donīt see your system. Please give usueful informations.

    Does your system support any other way (to...
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    6
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    240

    Closed: Re: stm32f103 update frimware from spiflash

    Hi,

    Since we donīt know your circuit and your requirements ... we can only tell you the "usual" way.
    (And so do the internet documents)
    If your circuit or requirement differs from the usual...
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    Closed: Re: Gprs modem and AT+ HTTP GET REQUEST?

    Hi,

    at first you need to test WHAT is causing this delay.
    Microcontroller? Modem? Access point? Routers? Server?

    Then you need to test WHY this is happening.

    I assume there are software...
  10. Replies
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    240

    Closed: Re: stm32f103 update frimware from spiflash

    Hi,

    when I do an internet search for: "stm32 spi flash bootloader" I get about 250,000 hits.
    (Didnīt you do this already on your own?)

    There are some application notes and documents directly...
  11. Closed: Re: How to find cutoff frequency of the circuits

    Hi,


    Circuit2 includes two "L", but your formula does not.

    According to your formula the cutoff frequency is independent of L .... I don't think this is correct.

    Klaus
  12. Replies
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    1,691

    Closed: Re: 12 Bit ADC with interfacing SPI in STM32

    Hi,

    Maybe it's time to start from the beginning ...
    An engineer should start with specifying the requirements (forget about all the ADC and SPI stuff)

    You show several different input...
  13. Closed: Re: ds1307 Rtc clock running slow by 6 second per day.

    Hi,

    Maybe a production problem
    .. some 32768 Hz XTALs donīt like ultrasonic cleaning.

    Klaus
  14. Closed: Re: Getting trigger signal for 555 timer from elevator button.

    Hi,

    there are millions. For a million of different requirements.

    But the most important - IMHO - is a proper PCB layout.
    The next important is an analysis of what really causes the error.
    ...
  15. Closed: Re: Getting trigger signal for 555 timer from elevator button.

    Hi,

    then itīs most probably an EMC problem, not a problem of the schematic.

    Use: (urgent)
    * PCB with solid GND plane
    * proper decoupling capacitors on ech supply pin of each IC
    * EMC filters...
  16. Replies
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    Closed: Re: Isolated Converter RS-422

    Hi,

    I donīt understand.
    Isolated but with no switching regulator.

    Due to the RS-422 you need energy to drive the 50 Ohms impedance signal lines. Where does this energy come from? Battery?...
  17. Closed: Re: Getting trigger signal for 555 timer from elevator button.

    Hi,

    There are many solutins.
    I'd go this way:
    * use a 10k pullup on TRIG pin to 12V
    * use a diode from TRIG (A) to the pushbutton (C)

    Klaus
  18. Closed: Re: ds1307 Rtc clock running slow by 6 second per day.

    Hi,

    Datasheet says:
    Did you read and follow the application note?

    Klaus
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    Hi,

    I agree.

    But the OP asks about series connection.

    Klaus
  20. Replies
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    1,691

    Closed: Re: 12 Bit ADC with interfacing SPI in STM32

    Hi,

    Please read all my posts...especially those with "sampling rate" and what is meant with "toggle NSS".
    It's all written already.

    Klaus
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    Closed: Re: L293d - Input Voltage (motor operation)

    Hi,


    General rule:
    Don't leave any inputs floating, neither at digital ICs nor at analog ICs...as long as it is not mentioned otherwise in the datasheet.

    Floating means the voltage level is...
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    Hi,


    The two resistors are no "15V" generators. They just divide the input voltage by 2.

    --> If your supply voltage is 10V then the voltage at the divider will be 5V.
    Depending on unsymmetry...
  23. Closed: Re: Battery cutoff voltage vs 0% battery voltage

    Hi,


    What advice do you expect?

    Cutoff voltage depends on battery, not on application.
    For sure you may measure the battery voltage...but it gives not much information about health and charge...
  24. Replies
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    [SOLVED]Closed: Re: Wiring of DC fans in Series

    Hi

    Try this:
    * NPN, PNP, 2x R = 4k7

    Wire it this way:
    * 30V --> NPN_C
    * NPN_E to PNP_E = 15V output
    * PNP_C to GND
    * resistors in series, one end to 30V, the other end to GND.
  25. Closed: Re: Holding button for 2s to trigger 555 timer

    Hi,

    On button press: the capacitor gets slowly discharged by a high ohmic resistor
    On button released: the capacitor fastly gets discharged via a diode

    Klaus
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