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  1. mrinalmani

    Powering a CMOS IC from a logic signal?

    Instead of using a buffer with all the peripherals, use one single buffer in series with the four SPI BUS lines. This will strengthen the driving capacity of the serial lines. Now you may use a 4.7K to 20K resistor in series with all the tap lines connecting individual peripherals. Even if a...
  2. mrinalmani

    thermal design LED PCB

    No simple formula, but as a starting point 0.5mW per centimeter square per degree celcius is acceptable for flat horizontal plates. Since your board is 100cm sq. the average power handling should be 50mW per degree celcius and a total rise of 6/.05 = 120C. FR4 boards should be ok if you use...
  3. mrinalmani

    Transistor as switch doubt

    Again you are speaking in terms of connected and not connected. Floating only means electrical isolation ie. a high impedance path. For that matter, even an unconnected pin in a microcontroller is connected through air. And during OFF state the collector and emitter are connected through...
  4. mrinalmani

    Transistor as switch doubt

    It means electrical isolation and not physical. There's no real importance of physical isolation in terms of electricity. We always speak of electrical isolation. The emitter is grounded, it is obvious that emitter is at reference voltage ie. 0V
  5. mrinalmani

    Transistor as switch doubt

    The emitter does not float, the collector does. And since the collector floats during OFF mode, its voltage is essentially the supply voltage.
  6. mrinalmani

    Decoupling capacitor/s value vs effective frequency coverage & anti-resonance.

    Re: Decoupling capacitor/s value vs effective frequency coverage & anti-resonance. Hello! Decoupling capacitors are used for for two purpose. 1. EMI reduction 2. Noise filtering. Put simply, the first situation arises because power takes a finite amount of time to be transferred from one...
  7. mrinalmani

    Inductor core saturation test, making sense of waveform.

    As already pointed out, the total series resistance is probably excessively large. But anyway this method for determining the saturation current doesn't look very promising to me. Firstly because there'e no sharp line for saturation. And secondly, the inductance is many a times, a non...
  8. mrinalmani

    thermistor cold is high impedance and hot is low impedance?

    1. During the dead time (when all switches are OFF) the inductor current must find a path. And the diode provides this path. 2. Placing a schottky diode between the C_B junction provides a path for the stored charges in the junction to discharge externally. Unless the charges are removed, the...
  9. mrinalmani

    thermistor cold is high impedance and hot is low impedance?

    @ Audioguru Yes you are right, the diode is not between B-E terminal therefore it does not appear to protect the B-E junction directly. But when used in an inductive H-Bridge, the protective nature of the diode is apparent at once. Infact had it not been for the internal diodes, external ones...
  10. mrinalmani

    thermistor cold is high impedance and hot is low impedance?

    The diode probably protects the Base-Emitter junction in case of reverse voltage. The B-E junction as a very low reverse breakdown voltage (around 10V) and can easily be destroyed if there's a reverse voltage across it.
  11. mrinalmani

    Capacitors in parallel , only one gets damaged why

    It is still unclear to me as to how the diode, coil and the capacitors are connected. Why dont you upload a sketch
  12. mrinalmani

    thermistor cold is high impedance and hot is low impedance?

    I didn't literally mean anywhere! I meant... having learnt the characteristics of a thermistor connect it to any design/circuit that it suits. Why be limited only to SMPS circuits? And ofcourse, a person who knows its characteristics, will not place it in parallel with a transformer!
  13. mrinalmani

    thermistor cold is high impedance and hot is low impedance?

    Having known the property of a thermistor, you can use it anywhere you please to
  14. mrinalmani

    state machine question

    @Venkadesh Your algorithm #13 indefinitely is simpler but it seems to belong to Greece! Would you please explain the basic logic behind it. And also, as far as the algorithm in post #12.... Storing of number is not required. Only the first level of remainder needs to be stored and updated as...
  15. mrinalmani

    Capacitors in parallel , only one gets damaged why

    Two factors will determine the inrush: 1. ESR 2. ESL Larger capacitors will generally have lower ESR but higher ESL, provided all are the same type, from the same manufacturer. Why dont you specify what type of capacitors you are using, also their voltage rating, capacitance and the voltage...
  16. mrinalmani

    thermistor cold is high impedance and hot is low impedance?

    A thermistor is essentially a resistor whose resistance depends strongly upon its body temperature. 100 degrees rise may reduce the initial resistance by as much as as 100 times, as opposed to normal resistors where he resistance would generally increase by roughly .01% to .02% for a 100 degrees...
  17. mrinalmani

    Capacitors in parallel , only one gets damaged why

    Wouldn't we generally use ceramic capacitors for bypassing? Were ceramic capacitors not that cheap in the 70s?
  18. mrinalmani

    state machine question

    See the attachments - - - Updated - - - See the first image, there's a typo in the second image
  19. mrinalmani

    state machine question

    Yes, Venkadesh is correct! Now let me discuss my algorithm, maybe that'll work. I'll attach a PDF, since its difficult to write equations in this editor.
  20. mrinalmani

    Glass Encapsulated Zener Diode

    Is it so appealing that it tempts you to buy it without being aware of even the gender!

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