Type: Posts; User: schmitt trigger

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

    And all of those crystals that you have changed, are they different vendors and part numbers?
    Did you purchase them from reputable vendors or from e-bay?

    Having said this: If you really require...
  2. Replies

    Closed: Re: Wiring of DC fans in Series

    The current draw of small DC fans do indeed change with rotation. Additionally, you cannot expect the two devices to draw the exact same current, even if they are the same brand and model.

  3. Closed: Re: How to calculate transformer winding losses

    You attachment 156028 returns an "invalid attachment" error.

    I am also curious what they mean parasitic leakage inductance losses.

    What I can recall from leakage inductance; that it is...
  4. Replies

    Closed: Re: power supply residual voltage

    I believe that you are using an incorrect problem description.
    What I believe you are describing, based on your description, is an input transient voltage caused the supply to produce a brief output...
  5. Closed: Re: Film capacitor failed in flyback smps at high temperature?

    It is really a combination of high ambient temp with localized hot spots due to high current pulses.

    I remember reading in a major capacitor manufacturer's catalog some "pulse rated" film caps.
  6. Replies

    Closed: Re: Photocoupler Saturation?

    If you are willing to invert the signal by looking at a signal from the collector instead of the emitter, you could use a cascode NPN transistor.

    But to reach 1 uS response time, perhaps you will...
  7. Closed: Re: Voltage to frequency conversion using VFC32

    I also would ask the question: How did you measure the frequency? With a frequency enabled DMM? With an oscilloscope?

    You really, and I mean really require to show us the output waveform with an...
  8. Closed: Re: Why are SMD components so much smaller than their THT versions?

    What ASDF44 said.

    If you attach the datasheets for the Mosfet you employed, we can help you with the thermal calculations.

    Even if you don’t require the help, for the benefit of other future...
  9. Closed: Re: Film capacitor failed in flyback smps at high temperature?

    Also, there is a clue on the first sentence on page 1 of the datasheet:

    Non-inductive construction using metalized Polypropylene....

    There are two ways to build a film cap that I know: wound...
  10. Closed: Re: Suggest Junior project at university (digital electronics)

    If you are not using a microcontroller, a traffic light is an interesting problem employing both sequential and combinational logic.

    You will require solving Karnaugh maps and state machines.
  11. Closed: Re: [moved] Why Zener getting heat at no load in Capacitor power supply arrangement..

    Did you understand my previous message? You require proper thermal management of the diode to properly dissipate the heat.

    For thru hole diodes, this means keeping the leads to the board as short...
  12. Closed: Re: [moved] Why Zener getting heat at no load in Capacitor power supply arrangement..

    If you have read the zener diode's datasheet carefully, which I suspect you have not, a zener's maximum power rating can only be achieved with a particular thermal configuration.

    For instance; the...
  13. Replies

    Closed: Re: "Self-Healing" 12V 30A Circuit

    Sort answer: yes.
    Actually, If you are using a microcontroller, you can design "smart" algorithms, such as:

    -Ignore very short overloads
    -Attempt a restart only if the overload is below xx...
  14. Closed: Re: Is a tantulum different from a microfarad tantulum cap?

    Most likely you have a defective tantalum cap.
    Where did you purchase it?

    I am sure that you are aware that there are many sub-standard or counterfeit components out there, specially in places...
  15. Closed: Re: TPS54560: Voltage is dropping when load connected

    Definitively check this one.
    This will happen if you are feeding a prototype regulator from a source, whose output drops due to incorrect current limit settings.

    Ask me how I know...:wink:
  16. Closed: Re: Simple transformerless power supply design

    After many, many years in this and several other online forums, one does indeed becomes exasperated with vague requests. And more so when one attempts to provide an answer, the OP will come back with...
  17. Closed: Re: Why logic High input is logic low on I2C data bus?

    To troubleshoot I2C communications, without headaches or confusion, you require either a logic analyzer or a scope with integrated decoding. I2C is such an ubiquitous standard that even the lowest...
  18. Replies

    [SOLVED]Closed: Re: Single or dual supply operation

    Short answer: as long as it is biased within its common-mode input range, it makes no difference.
  19. Closed: Re: Harmonics in a 12 V brushed DC Motor

    Please explain what you mean by 12 commutators?

    A commutation is created with a pair of brushes and the slotted slip ring. I believe that you really mean 12 slots in the slip ring.

    It would be...
  20. Closed: Re: USB PD Lab Power Supply, flyback- vs forward-converter, pro's vs con's?

    which means the such a port is capable of supplying up to 20V @ 5A or 100W of power.....

    I have to ask: an USB port is capable of providing 20 volts ?
  21. Closed: Re: Runtime of clock using alkaline D cells instead of AA batteries

    For alkaline batteries, the capacity is NEVER calculated to zero volts, but an end voltage of 0.9 volts per cell.

    But from a battery datasheet, check the end voltage value. The 0.9 volts I gave...
  22. Replies

    Closed: Re: Protection circuit help

    Funky startup circuit indeed!
    Have you actually tested it in a breadboard?

    You are pulling U4’s output to Vbat-Vf, roughly 23 volts, from an IC which is presumably powered by 3.3 volts. Really?
  23. Closed: Re: Do XR7 250Vdc 1206 SMD capacitors exist

    100 uF? At 250 V? With an X7R ceramic?

    It will be a tight (or perhaps impossible fit) on a 1206 package.

    Have you checked the selection catalogs from Murata, AVX or TDK?
  24. Replies

    Closed: Re: Cheap Mains harmonics tester

    Do you require individual harmonic level, or would a THD measurement be sufficient?
  25. Closed: Re: How can I tell if my laptop screen is LED or LCD?

    Backlighted displays, whether CCFL or LED back light when viewed in a darkened room with a flat black screen, will have some light leakage.

    To determine whether it is CCFL or LED, you would have...
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