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Type: Posts; User: wwfeldman

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  1. Replies
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    Closed: Re: Not enough IOB of a certain FPGA

    where are you getting 128 bit parallel input, and 256 bit parallel input?
    it takes a lot of PWB space, but 16 74299 type 8 bit universal shift registers would do it
    and you would need to reconvert...
  2. Replies
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    91

    Closed: Re: Not enough IOB of a certain FPGA

    serial I/O ?
  3. Closed: Re: Does this ARM Microcontroller development board I have designed work?

    no idea if it will work
    however:

    IF Vcc is 3.3 V, 24.9 ohm resistor R2 may be too small
    I don't know the current capability of your processor

    you're having PA13 act as a source for LED2
    R1...
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    Closed: Re: Rotary capacitor physics and design

    you haven't specified the capacitance range you're looking for

    since 3000 RPM is 50 rev/sec, maybe there's a better or different way to produce a
    50 Hz signal than this rotating capacitor
  5. Closed: Re: UA78M33CDCY 3,3 volt regulator will not regulate at input voltage above 12 vol

    just for fun, try one or two from digikey, or newark, or jameco,
    all of whom have been around for a long time.

    or, maybe direct (?) from TI

    or, get a larger case, such as TO220
  6. Closed: Re: UA78M33CDCY 3,3 volt regulator will not regulate at input voltage above 12 vol

    its not clear, since its supposed to have over current and over temperature protection built in
  7. Closed: Re: UA78M33CDCY 3,3 volt regulator will not regulate at input voltage above 12 vol

    the data sheet for the 3.3 V part is up to 20 V input, not 25V
    but that's splitting hairs compared to your reported results

    is there a load in addition to the 560 ohm resistor?
    did you lay out...
  8. Replies
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    Closed: Re: Rotary capacitor physics and design

    so you're plan is to have 20 stationary copper discs, each about 400 cm2, side by side, (so you ave a plate area of about 8000 cm2) each with a rotary partner on its own shaft
    so they are wired in...
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    Closed: Re: Rotary capacitor physics and design

    when you calculated the capacitance, you talked about the area, 8000 cm^2
    is that the area of 2 neighboring plates?

    the rotary variable capacitor FvM has in post #3 consists of many pairs of...
  10. Closed: Re: Best Solution to use DOT POINT by REVERSING 3rd. one Digit of 4-digit seven segme

    I didn't check the power/ground connections.
    So when you rotate M10, you'll have to take care of that.

    It looks like a little re-wiring will solve the problem
  11. Closed: Re: Best Solution to use DOT POINT by REVERSING 3rd. one Digit of 4-digit seven segme

    for a standard 7 segment display, top to bottom
    horizontal A, G, D
    left side F, E
    right side B, C
    decimal point lower right


    for a standard 7 segment display, rotated 180 degrees, top to...
  12. Closed: Re: Best Solution to use DOT POINT by REVERSING 3rd. one Digit of 4-digit seven segme

    since the colon is always on, or blinks the seconds, why not use a pair of LEDs
    mounted between the hour and minutes?
    then you don't have to rotate minute 10, invent new connections for 0 through...
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    Closed: Re: Rotary capacitor physics and design

    how high a capacitance do you want?
    please expand on 1000K - is that capacitance? is it desired dielectric constant? units?

    variable capacitors have been around for a long time
    they were the...
  14. [ARM]Closed: Re: Environmental testing of Unit inside Chamber

    are the ICs all speced to work properly at at least the conditions of your test?

    was there any condensation at 40 deg C and 95% RH?
    does the humidity come up first, or does the temperature come...
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    Closed: Re: Need help to design Pi filter

    an explanation and equations:

    https://electronicscoach.com/pi-filter.html
  16. Closed: Re: Modulation scheme of this pulsed/two-frequency radar system

    I don't know - taking a stab in the dark

    are your 2 frequencies low level signals presented to the transmitter,
    or are they a transmitted frequency and a reflected frequency, as betwixt...
  17. Closed: Re: Power supply duel_5v/15v from 230:15v 1amp transformer

    if the 230V is a little high, you'll get a little more on the 15 V side

    15V RMS is 21.2 V peak
    one diode drop through the bridge, a second diode drop through D1,
    and a third diode drop on the...
  18. Replies
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    Closed: Re: MAX485 ground isolation

    153693

    note dotted line separates the controller side from the motor side

    replace the max 485 part with maxm22511 as suggested by asdf44
    it costs more, as you said, but it may make the...
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    Closed: Re: MAX485 ground isolation

    you aren't paying attention
    the dotted line separating the two sides must be continuous and
    there can be no physical connection from one side to the other

    no wires may cross the boundary

    only...
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    Closed: Re: MAX485 ground isolation

    redraw the circuit

    draw a line down the center of your page

    put the motor and encoder on the right,
    put the controller on the left
    put the optocoupler in the middle - the controller side on...
  21. Closed: Re: Find dc voltage gain and phase margin from graph

    https://www.google.com/search?client=firefox-b-1-d&q=gain+margin

    you need to extend the range of your graphs
    you need to know where the gain graph crosses 0 dB, so the scale has to include 0 dB...
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    Closed: Re: Push button with Pull Up

    @ansh11
    a toggle switch is not a push button
    a toggle switch, in its simplest form, is an on off switch
    the switch in your photograph is a momentary contact push button - likely close on push
    ...
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    Closed: Re: Current transformer and reading

    you apparently have a current transformer and get actual currents.
    you need to determine what is too much current
    then look at your circuit to see what the output of the current transformer is ...
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    Closed: Re: Integration by parts

    this is a pretty good explanation of integration by parts:

    http://tutorial.math.lamar.edu/Classes/CalcII/IntegrationByParts.aspx

    in your case, choose the substitutions u and du appropriately
  25. Replies
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    Closed: Re: Push button with Pull Up

    which component are you talking about?

    the resistor?
    the push button?
    the connector?

    the resistor:
    click on new part
    scroll down to rcl library
    if you like european symbols, use R-EU_...
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