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  1. Closed: Re: 2:1 Multiplexer with open drain Outputs IC

    The original request can be solved with a single 74HC4066 and 4 resistors:

    156598

    The unmarked resistors should not be critikal. Use 10K or whatever.
    The 1k resistor will affect the maximum...
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    [SOLVED]Closed: Re: fixed point arithmetic in c

    The two's complement format is good for addition/subtraction, but bad for multiplication/division.
    You want to multiply Q1.15 values 23166 (0.707) with 65535 (-0.0003)
    The simplest solution is to...
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    Closed: Re: instruction set translator

    This is probably not a small assignment.

    It is easy for the 8086 to emulate the 8051.
    It is very difficult for the 8051 to emulate the 8086.

    If you already have the EPROM contents, only...
  4. Closed: Re: Regulating temperature of mains connected heating element: Skipping mains half cy

    The commercial products I have seen use a fixed cycle time of about 40 seconds. The regulation is done by changing the "on" time while keeping the cycle time constant.
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    Closed: Re: Where does this equation come from?

    There is pseudo C-code in this article:
    https://www.edn.com/design/signal-processing-dsp/4006766/Tutorial-Software-implementation-of-Trigonometric-Functions-using-a-CORDIC-algorithm
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    Closed: Re: Where does this equation come from?

    That is probably only true if you have a hardware multiplier available with enough number of bits. One feature of the CORDIC algorithm is that there is no multiplication involved. Only shift, add,...
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    Closed: Re: Where does this equation come from?

    That range is enough since you can always use other ranges by simple trigonometric identities.
    However, it should be possible to extend the vector algorithm to +/- pi by adding new first rotations...
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    Closed: Re: Where does this equation come from?

    In vectoring mode (page 5), if you start with (x, y) values corresponding to 30 degress, yi will be negative after the first rotation, since the first rotation is 45 degrees. Every rotation will...
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    Closed: Re: Where does this equation come from?

    The logic is that the vector is always rotated in the direction that gets yi closer to zero.
  10. Closed: Re: NPN having its VBE protected against reverse voltage....but unecessary?

    I would never allow a transistor to go into "reverse VBE zener mode" unless that is the intended operation. It can permanently reduce the gain of the transistor, as dick_freebird mentions in post #3....
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    Closed: Re: Logic duplication and optimization

    I would probably use "Method 2".
    I will be confident that the synthesis result is optimal.
    I will be able to see the intermediate sum "a+b" in the simulator, and easily connect it to...
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    [SOLVED]Closed: Re: Protect FPGA Pin from negative voltage

    You must also look at the Vf/If diagram. To keep Vf below 0.5V, the current can only be a few tens of mA.
    I suggest that you make sure that the current in the diode never exceeds 1-10 mA (you select...
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    [SOLVED]Closed: Re: Protect FPGA Pin from negative voltage

    BAT54 directly between the FPGA pin and GND. The resistor is only necessary if the current through the BAT54 will be too high (set the limit somewhere in the range 1-10mA) without it.
    The resistor...
  14. Closed: Re: 1200 baud data transfer over audio passband of cellphone. Is that possible?

    Landline phone stations transferred the actual audio samples with 8 bits non-linear sampling at 8 kHz = 64 kbits/s.
    Cell phones tries to get similar audio quality with a much lower bit rate. To...
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    Closed: Re: Data Transfer over long twisted pair cable

    "CAN FD" is specified for 10 meters maximum distance, the requirement here is 1500 meters. Also, the expected average bit rate is probably below 4 Mbit/s:...
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    Closed: Re: Data Transfer over long rwisted pair cable

    ADSL hardware seems to be perfect for this:
    https://en.wikipedia.org/wiki/Asymmetric_digital_subscriber_line
  17. Closed: Re: Error (10028): Can't resolve multiple constant drivers

    Ok, now I see that clk is your SPI clock from the master.
    I suggest that you use some other high speed clock as your only clock in the whole design and treat all SPI signals as normal I/O....
  18. Closed: Re: Error (10028): Can't resolve multiple constant drivers

    Only drive signals from one process block.
    Use as few clocks as possible. In this case only use clk as a clock, and detect the cs edges inside the "always@(posedge clk)" process block.

    Don't set...
  19. [SOLVED]Closed: Re: Sending data from pic microcontroller to web server using ethernet.....

    What PIC processor? Forget TCP on a small one. Use UDP to communicate with a "helper" software on some server, that can access the web/php page.
    It helps if you can hardcode the MAC address of the...
  20. Closed: Re: How two nodes are communicating in CAN bus protocol?

    Use a CAN bit timing calculator.
    Online: https://www.kvaser.com/support/calculators/bit-timing-calculator/
    Windows program: https://www.intrepidcs.com/products/free-tools/mb-time-calculator/
    More...
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    [SOLVED]Closed: Re: USB to RS232 exactly similar to COM1

    You must have connected the MAX3232 wrong. The RS232 outputs from MAX3232 are on pins 7 & 14, and one of them should be connected to pin 3 (TXD) of a male DSUB-9 if you want to emulate a PC serial...
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    [SOLVED]Closed: Re: USB to RS232 exactly similar to COM1

    The +/- 3V is correct for the RS232 receiver, so for short cabling it should work if the transmitter gives at least +/- 3V.

    I don't think the voltage levels is the problem here.

    Some older...
  23. Closed: Re: How two nodes are communicating in CAN bus protocol?

    That was the intention when the CAN bus was designed, but that functionality is normally handled by software, so you can design your system in other ways.
    There are several ways to use the CAN id...
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    Closed: Re: HP 54520A Blown Fuse Problem

    The crowbar was also my thought in post #23, but since it is on the secondary side and the fuse blows even with the main switch transistor Q3 removed, it must be something else.
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    Closed: Re: HP 54520A Blown Fuse Problem

    It can be an isolation problem in the common mode choke L1. Remove it and bypass with two wires. If the scope works, get a replacement choke, or rewind it yourself on the existing core..
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