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Type: Posts; User: betwixt

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  1. Closed: Re: Displaying the time parameter using Timer interrupt

    I couldn't read code so badly formatted and commented. Please stick to one style to make it easier to read.
    I think I managed to unscramble it as:


    void interrupt isr(void)
    {
    ...
  2. Closed: Re: 7 segment LED with integrated zener diode .

    LEDs are already constant voltage devices so there is no point in placing a Zener across them. If reverse voltage may be an issue, a normal diode will work just as well. As Klaus stated, the problem...
  3. Closed: Re: Where to buy Electronics components in UK for domestic use?

    Try Rapid Electronics https://www.rapidonline.com/ they carry vast stocks of components and construction materials and for small deliveries they use Royal Mail.

    Select 'industry' when you get to...
  4. Closed: Re: Basic 12v Battery VOLTAGE METER, more resolution needed

    That is exactly right. I will try to explain my reasoning about the shunt regulator method:

    A diode blocks the flow of current in its 'reverse bias' condition (when the anode is more negative then...
  5. Closed: Re: Glow LED on specified counter values 0-500 in 89c52 uC

    from my post #9:

    Subtract the increment from the counter then check the modulo for zero.
    You did it the other way around! Subtracting Counter from 10 results in a 'negative' rollover of the...
  6. Closed: Re: Basic 12v Battery VOLTAGE METER, more resolution needed

    Agreed Klaus, but using the diodes as a shunt voltage regulator like that means they have to pass more than the combined current of all the LEDs in 'on' state to ensure the voltage stays steady,...
  7. Closed: Re: Glow LED on specified counter values 0-500 in 89c52 uC

    Subtract the base values 10 and 15 from the Counter value and if the result modulo 10 and 15 is zero, turn the LED on, otherwise turn it off.

    Make sure 'Counter' is declared volatile.

    Brian.
  8. Closed: Re: Basic 12v Battery VOLTAGE METER, more resolution needed

    As I see it, the only purpose for having R7 at all is to drop the LED voltage to about 2.5V across the four diodes. I'm not sure why that is necessary as the LM3914 already contains current...
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    Closed: Re: Power Supply Design for timer application

    You must understand the problem first. Three phase uses three wires so you cannot 'magic' an independent reference from them unless you use a transformer (or maybe more than one transformer).
    ...
  10. Closed: Re: Waveform saving upon trigger in windows from Oscilloscope

    I have a Tek MSO3032 but I use Linux so the Windows software is of no use to me. For screen capture I simply plug it into my network (I think your model supports that) and use a web browser to...
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    Closed: Re: how to boost microvolts to higher voltages?

    The LM224 can run off 4V but the highest voltage it can output is Vs-1.5.

    The information you need is in data sheets, you should be particularly interested in:
    Being able to work from a low...
  12. [SOLVED]Closed: Re: Working of Analog and digital convertors with its significance

    Not the top one or the bottom one, the second from the left in the middle column looks like the answer.

    Or of course you could give us some clues....


    Brian.
  13. Closed: Re: 3-phase Δ-connected 11kV Open Circuit Fault Detection?

    The problem with sensing after the voltage is dropped is the transformer typically sits across two of the phases (delta-Y configuration) so it is still prone to picking up voltage from after the...
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    Closed: Re: how to boost microvolts to higher voltages?

    That depends entirely on whether you want an exact but bigger voltage or one inverted in polarity. The amplification is the same regardless.

    Brian.
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    Closed: Re: Issues with driving 16x2 LCD

    That is risky code!
    Use a variable to hold the LCD data before writing it back, there is no guarantee the lower bits of LATC hold the data on the pins, in fact if the lower bits of PORTC are used...
  16. Closed: Re: 3-phase Δ-connected 11kV Open Circuit Fault Detection?

    Assuming there is a load on the lines, I would use current monitoring rather than voltage monitoring. An open line will not conduct any current but there could still be voltage at both sides of a...
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    Closed: Re: I2C copper trace lost continuity

    I would say a one off problem and not in any way related to the function of the line. Most likely there was the thinnest of copper there due to contamination on the original copper board and moisture...
  18. Closed: Re: Old capacitor needs replacing not sure what to replace with.

    They should be fine. They exceed the rating of the originals and are also probably more reliable and effective than the original type too.

    Brian.
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    Closed: Re: Issues with driving 16x2 LCD

    Certainly it's a timing issue but your code is still much longer than needed. All those "LCD_D4 = (out_char & 0x10)?1:0;" and similar statements are to allow for the LCD to be driven from mixed...
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    Closed: Re: Zener Diode with LC circuit

    Sounds like you are inventing the SMPS concept again!
    A Zener only works as a clamp in reverse biased direction, in forward mode it works like a normal diode.

    Brian.
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    Closed: Re: Issues with driving 16x2 LCD

    You have a lot of duplicate code in there making it more difficult to read.

    Note that writing commands and data to the LCD only differ by the level on the RS pin so you can combine the two...
  22. Closed: Re: Old capacitor needs replacing not sure what to replace with.

    Look here at the 'Wima' branded capacitors.
    https://www.rapidonline.com/Catalogue/Search?Query=capacitors&Attributes={%22Voltage%22:[%22250V%22]}
    They are actually quite small. If the appearance...
  23. Closed: Re: Old capacitor needs replacing not sure what to replace with.

    Must be my eyesight failing... yes, it is 5nF although 50nf would probably work better.
    There is a small 'Y' near the value and a small 'X' near the 100nF.

    Brian.
  24. Closed: Re: Old capacitor needs replacing not sure what to replace with.

    I've seen this before, it probably dates back to the 1950's or very early 60's before PVC was used for insulation. The wires are covered in some kind of rubber insulation that dries out and fractures...
  25. Closed: Re: serial communication betwen 8051 and Arduino

    I agree, the code is very badly formatted and confusing to say the least.

    Additionally, the resistor packs in the schematic seem to do nothing useful.

    The Arduino end should work but all it...
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