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Type: Posts; User: prairiedog

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  1. Closed: Re: L1 and C1 value for EMI filter design ?

    There's no simple values to use, EMI is not that easy. Filter theory doesn't always work here, I use a spectrum analyzer and current probe to measure the emissions. The EMI standard being designed to...
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    Closed: Re: load sensing circuit/relay

    I have used a small current-transformer with as many (primary) turns wrapped around it as I can fit. The CT secondary goes to a bridge rectifier and then to turn on an opto-coupler's LED (in an SSR)...
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    Closed: Re: Ferrite bead usage in ADC's

    EVAL-AD1955 webpage offers no schematic or user guide that I can find. Nor does Digikey or Mouser, who sell the EVAL board for $555. They must have changed the grounding strategy at some point, but I...
  4. Closed: Re: Automatic Water Level Controller - Dynamic Dry-Run and OverLoad Current Calc Rela

    One big problem is induction motor current does not drop much with no or light loads. The magentization current is always high. You need to measure true power to the motor to determine if it has no...
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    Closed: Re: Ferrite bead usage in ADC's

    Follow up - I measure 16 ohms between AGND and DGND on the AD1955 DAC IC. In the ADI Engineer Zone forum, the EVAL board designer says the two grounds are connected to a ring on the die. So I am...
  6. Closed: Re: How the washing machine Automatic Load Sense works?

    It's easy to quantify the mass of clothes in the drum. A look at any Maytag schematic will reveal the algorithm used.
    OP seems to want the answers to his homework or something, instead of a...
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    Closed: Re: Ferrite bead usage in ADC's

    I grumble about Adafruit's intentions because putting a ferrite bead between system GND and the ADC GND doesn't work here- because the ADC IC only has one ground pin. The result is digital currents...
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    Closed: Re: Ferrite bead usage in ADC's

    I read this in OP's post and thought I'd answer that question:
    "... They place a ferrite bead between two grounds to "isolate" one from the other... Can anyone advise me on this?... "
    It's on...
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    Closed: Re: Yaesu FT-101 dynamic mic question

    Dynamic mics are around 600 ohms so it would be fine, the JFET amp is 47k input impedance.
    But what is going on with J3 pin 2? An electret condenser mic would need power, a resistor to that so maybe...
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    Closed: Re: Ferrite bead usage in ADC's

    The ferrite bead prevents RF from the digital circuitry from getting coupled to the analog side.
    OP's SAMD21G18 will generate up to 48MHz hash+harmonics on DGND which you do not want on your AGND....
  11. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    Audio electronics design is full of superstition and speculation. There might be some voodoo involved. I just use a scope or spectrum analyzer and measure things.

    The snubber values depend on the...
  12. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    I took some 60Hz rectifier snubber measurements from both a homemade DAC and cheap chinese clone Lehmann headphone amp, similar to OP's project, and some breadboard variations.
    For the Lehmann...
  13. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    Putting capacitors across rectifier diodes is old-school, it lowers the ringing resonant frequency but does lower spike amplitude, so it does protect the diodes from transients.
    You can get MHz...
  14. Closed: Re: What is meant by "coating" when PCB track spacing is concerned?

    Coatings mean conformal coating (UL/CSA/EN/BS approved) to keep dust and moisture off the PCB and allows you closer spacings. PC board solder-mask is not a suitable insulator towards safety, as the...
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    [SOLVED]Closed: Re: HEI primary current duration

    You have to shut off the IGBT at precisely the right (spark) time, so you are always calculating backwards when to start the next dwell period.

    If you have reached max. dwell time before spark...
  16. Closed: Re: Beckman Industrial 9020 - Poor focus with no adjustment

    Service manual (in French): The Boat Anchor Manual Archive (BAMA), Beckman 9020 has schematics
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    [SOLVED]Closed: Re: HEI primary current duration

    Yes but you need to allow extra time- for the spark to finish, which can vary a bit due to plug gap and plug+cable resistance, misfires etc. Also, dwell varies with system voltage so assume 11V say,...
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    [SOLVED]Closed: Re: 12 vdc led running very hot

    The resistor and LED are around 23mA so the 0.25W resistor dissipates 0.28W and will get quite hot. I find this typical with LED stuff from china, they drive things a little past their max.
    I used...
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    Closed: Re: Residential Wiring Offset Voltage

    Electrical codes require neutral to be bonded to earth ground, after any (distribution) transformer and at the service entrance, breaker panel. A distribution transformer is step-down from say 15kV...
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    Closed: Re: Residential Wiring Offset Voltage

    It's specified as a total voltage drop, for both of the hot and neutral conductors, from the point of view of efficiency. You don't want large voltage drops due to thin wire. Residential mains cable...
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    Closed: Re: About Separating Supplies on PCB.

    Note the MAX5875 Eval board used three PCB ground sections: AGND, DGND, CLKGND. Maxim also used DAC output common-mode chokes and output transformer.
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    Closed: Re: Residential Wiring Offset Voltage

    NEC 210.19 has a limit of 5% total voltage drop for sizing conductors on branch circuits. 5% of 120VAC is 6V or 3V then for neutral. At the load (outlet), neutral goes above ground because it's 1/2...
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    [PIC]Closed: Re: 7Amp Heater and PWM using MOSFET

    Heaters (and their wiring, cables) have parasitic inductance, so the mosfet will see overvoltage spikes at switch-off, which can damage it. A fast-recovery diode across the heating element or a RC...
  24. Closed: Re: Conducted EMC equipment for 60W offline PSU

    I don't know of any company offering such a facility- you're asking for EMC lab benefits without the cost. EMC labs have calibrated equipment and shielded rooms, accreditation, operations staff etc....
  25. Closed: Re: Power Supply for M95 GSM module to be compatible with ATEX limitations.

    I did a Zone 0, IS cell modem design. Main power is a 6V lead-acid battery. 60079-11 does not allow active current-limiters. I used an LDO for 3.7V 2A power to the modem module. I thought a...
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