Search:

Type: Posts; User: c_mitra

Page 1 of 20 1 2 3 4

Search: Search took 0.03 seconds; generated 8 minute(s) ago.

  1. Replies
    13
    Views
    453

    Closed: Re: fastest multiplication alghorithms

    The bug was actually associated with the floating point division processor (NDP) - divisions take considerably longer time and they use different lookup tables (if my memory is right). There was no...
  2. Replies
    13
    Views
    453

    Closed: Re: fastest multiplication alghorithms

    For 8 bit unsigned int, you will need a table 256X256 in size. The products shall need 16 bit storage.

    For the slowest method (school book way) it is just 8 shifts and 8 additions.
  3. Replies
    36
    Views
    613

    [SOLVED]Closed: Re: Average vs RMS load-current for LDO design

    A quick summary:

    Avg value of noise = const DC offset + avg (noise) --> zero (second term) (Avg of noise is always zero except for the offset; or you can consider the offset as the average if you...
  4. Replies
    3
    Views
    172

    Closed: Re: How to make a coil to be resonance?

    It already have a natural resonance frequency; because of internal parasitic capacitance. You can either measure it directly or estimate it indirectly.

    You have made an inductor; it needs some...
  5. Replies
    36
    Views
    613

    [SOLVED]Closed: Re: Average vs RMS load-current for LDO design

    But this needs more details.
  6. Replies
    9
    Views
    512

    Closed: Re: Processor overheating

    I am not so fortunate; inside temp in winter (Dec-Jan is the coldest in my part of the world) around 27-30C (outside it can be 40C in direct sun). In summer, inside temp is around 35-38C and the...
  7. Replies
    36
    Views
    613

    [SOLVED]Closed: Re: Average vs RMS load-current for LDO design

    In that case, the rectified output of an AC is not DC; but I am not sure what is the more common understanding.
  8. Replies
    36
    Views
    613

    [SOLVED]Closed: Re: Average vs RMS load-current for LDO design

    Not correct. This is true only for a constant current.

    I guess I need not elaborate.
  9. Replies
    36
    Views
    613

    [SOLVED]Closed: Re: Average vs RMS load-current for LDO design

    It is surprising; a small digital circuit as a load to a LDO regulator is not expected to act like this! Can you please provide more details?
  10. [SOLVED]Closed: Re: Lenovo laptop problem during installing LINUX OS

    Modern linux is quite robust: did your installation went through all right?

    Please mention the specific distribution of Linux you are using. Those forums can provide more fine grained response.
  11. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    True. As long as it works. A good power supply can make several iota:s of difference. A simple capacitor snubber across the rectifier diodes can reduce noise from the mains (power line noise) and...
  12. Replies
    9
    Views
    512

    Closed: Re: Processor overheating

    Good that you found a solution. You need to estimate the heat being produced by the device and how to transport this heat to elsewhere. You may still need a good heat sink on the Peltier device.
  13. Replies
    15
    Views
    970

    Closed: Re: Current increase electrolytic cell

    I am not sure whether you are conducting these experiments with sufficient care and safety protection. Potassium permanganate mixed with sulphuric acid is a very powerful oxidant and can cause fire...
  14. Replies
    15
    Views
    970

    Closed: Re: Current increase electrolytic cell

    Hydrogen gas will appear at the Al electrode when there is no current. As soon as you start drawing current, hydrogen ions will move towards the Cu electrode and get discharged there.

    The internal...
  15. Replies
    15
    Views
    970

    Closed: Re: Current increase electrolytic cell

    Hydrogen evolution is the basic reaction. The hypochlorite acts a depolariser and you will get HCl produced as a result. HCl is an acid and will get neutralised by the alkali (NaOH). Therefore there...
  16. Replies
    22
    Views
    860

    Closed: Re: sine/cos encoder to digital

    Actually, the formal expansion for atan(x) is:

    atan(x)= x -x*x*x/3 +x*x*x*x*x/5 -x*x*x*x*x*x*x/7 +....

    This series expansion converges slowly (to get 4 decimal accuracy, you will need perhaps...
  17. Replies
    22
    Views
    860

    Closed: Re: sine/cos encoder to digital

    Take a look at the original set of data.

    Sometimes a plot says a lot. So I plotted the last column against column 1.

    This is what I get:

    156681

    The angle data points are not really...
  18. Replies
    9
    Views
    512

    Closed: Re: Processor overheating

    You need to tell us the difference in the two environments before we can make out some sense of the two readings.

    Then also interchange the two and see the temp rise. That will also give us some...
  19. Replies
    15
    Views
    728

    Closed: Re: Implementation of sine cosine using LUT

    You are right; the look up table has to be computed outside. Only the table has to be stored.

    If you are using a 8-bit interger, -1 to +1 need to be mapped into 0 to 255.You will perhaps get an...
  20. Replies
    25
    Views
    869

    Closed: Re: Issue with relay and snubber

    Right. The total energy stored in the motor is being dumped on the capacitor and resistor. With a 1/2 HP motor, that can be significant.

    Because the load is supplied with AC, we do not know at...
  21. Replies
    15
    Views
    728

    Closed: Re: Implementation of sine cosine using LUT

    Right. A large part of the sine curve can be approximated by a straight line; see the graph below.

    156667

    As sin(x) is always within +/-1, 10% accuracy means only one decimal significant digit....
  22. Replies
    15
    Views
    728

    Closed: Re: Implementation of sine cosine using LUT

    Using trigonometric identities.

    For 90 >x >45, we use the formula

    sin(90-x)=cos(x)=sqrt(1-sin^2(x))

    Actually the sinus and cosinus tables are the same (one table does both the work).
  23. Replies
    15
    Views
    728

    Closed: Re: Implementation of sine cosine using LUT

    What you are suggesting is called linear extrapolation; look up tables may use actual values and can be more accurate.

    In good old days, we had books that had many kind of tables: log,...
  24. Replies
    15
    Views
    970

    Closed: Re: Current increase electrolytic cell

    The alkali (sodium hydroxide) removes the protective oxide layer from the Al surface. It also attacks the metal with production of Hydrogen. The gas bubbles you see are hydrogen formed by oxidation...
  25. Replies
    25
    Views
    869

    Closed: Re: Issue with relay and snubber

    I do not know how I overlooked that. Blame it on old age.

    Of course you are right. Something is fishy.
Results 1 to 25 of 500
Page 1 of 20 1 2 3 4