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  1. Replies
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    Closed: Re: Cw decoder by ik3oil

    I can't see anything obviously wrong but you should keep the wiring as short as possible. The PCB design around the crystal is horrible!

    I think there should be loading capacitors at both ends of...
  2. Closed: Re: Where to get schematics about SCRs full-wave triggering circuits ?

    You are not reading what Klaus explained - it is current that triggers the SCR but it does come from the discharging capacitor.

    Your schematic is correct but the scope settings are not. Switch...
  3. Closed: Re: Where to get schematics about SCRs full-wave triggering circuits ?

    Back to basics eagle1109 - if you charge up a capacitor, it doesn't matter what value or what the voltage is, then short it out, how much current flows out of it?

    Try this simulation: use...
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    Closed: Re: water flow detection in a pipe

    I agree with Klaus, at least tell us if this is a 'one off' to build at home or a mass produced item, it makes a big difference to the solution.

    In general, you could consider acoustic devices,...
  5. Closed: Re: how to select capacitor for ruhmkorff coil?

    If you haven't got an oscilloscope or frequency counter, try using a mobile phone app that measures audio frequencies (there are many!) and let it hear the output of a nearby AM radio. The 'buzz'...
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    [AVR]Closed: Re: Temprature sensors. LM35 vs MCP9700

    Assuming the ADC is 10-bits, with 1.097 vREF the ADC would read 373 with 400mV input.

    Where does the 500 come from in your calculation?

    For reference, I use MCP9701 devices extensively, they...
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    Closed: Re: Cw decoder by ik3oil

    Can you show a picture of the screen please. I am trying to see if the dots are being sent to the LCD by the software or if the dots are caused by a hardware problem.

    Brian.
  8. Closed: Re: Resistance of component bag made of "reddish" ESD plastic?

    Video #7 is quite honestly nonsense. Did anyone notice the comparison between pink plastic and metal flashed bags wasn't done properly? Pink plastic is (I think it's an amide additive) designed to...
  9. Closed: Re: how to select capacitor for ruhmkorff coil?

    Yes, with 50+ years of experience, much of that designing test equipment!

    Brian.
  10. Closed: Re: how to select capacitor for ruhmkorff coil?

    I would argue the opposite. It helps to preserve the contacts although there is some additional loss as the capacitor is shorted out and discharges into the contacts. The coil is essentially a high...
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    Closed: Re: Ferrite vs wire antenna for MW

    The wire will win easily but if this is an energy harvesting experiment you should be aware that a few microwatts of power is all you are likely to get.

    Brian.
  12. Closed: Re: how to select capacitor for ruhmkorff coil?

    It isn't necessary to use one at all but I would suggest something in the region of 0.22uF if you insist on using one.

    These are not user friendly or efficient devices, you can get better results...
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    Closed: Re: Ferrite vs wire antenna for MW

    I used to listen to New York and Boston stations here in the UK years ago, before the noise pollution became to great. That was on a long wire antenna.

    An outdoor antenna will undoubtedly work...
  14. Closed: Re: computer parallel port external relay control

    Frank, it would be helpful to know how you control the parallel port at the moment. Obviously some software is involved and it probably writes directly to the ports hardware address. You would have...
  15. Closed: Re: Resistance of component bag made of "reddish" ESD plastic?

    All of this goes around in circles. Static is a fact of life, it isn't the voltage that causes harm, it is the voltage difference when charged items touch each other.
    If voltage alone did harm,...
  16. Closed: Re: computer parallel port external relay control

    The real problem is finding a parallel port on a PC these days. When one does physically exist you have to jump through hoops to bypass the vitualization so you can talk to real hardware.

    A more...
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    Closed: Re: Cw decoder by ik3oil

    The photographs show a 16x1 LCD.
    The code is for a 16x2 LCD.

    In the "inilcd" routine, the line that sets the display geometry is You can edit the binary for other display sizes. The length of...
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    [AVR]Closed: Re: Temprature sensors. LM35 vs MCP9700

    TA[1] = TA[1] + (analogRead(A1)- 500)*vREF/1024*100;
    Are you sure that subtracting 500 is the correct value. I'm not familiar with the Arduino Nano but the final measured voltage should have around...
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    [AVR]Closed: Re: Temprature sensors. LM35 vs MCP9700

    .... and did you compensate for the zero offset on the MCP9700? The devices are not directly interchangeable.

    Brian.
  20. Closed: Re: Where to get schematics about SCRs full-wave triggering circuits ?

    FvM - not according to the schematic in post #42. With the pots at minimum resistance it places 240V AC across the 100uF capacitor.

    Not quite true, if you take your half cycles and trigger at 90...
  21. Closed: Re: Where to get schematics about SCRs full-wave triggering circuits ?

    Look at what happens if you set both potentiometers to minimum resistance - you effectively connect the capacitor across the incoming AC. That means the capacitor has to be rated for at least 250V...
  22. Closed: Re: PIC16F877 interface with ds1307 ...RTC running 10 sec slow

    Timekeeping is internal to the DS1307 so the interface code is unlikely to be the problem. Taking 70 seconds to complete one minute implies the RTC crystal is running at 28.086KHz instead of...
  23. Closed: Re: Where to get schematics about SCRs full-wave triggering circuits ?

    The schematic shows a normal diode but the text calls it a 'trigger diode'. In a real circuit a diac would be used. A diac isn't like a normal diode, it doesn't conduct at all in either direction...
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    Closed: Re: UC3845 ETD29 transformer PWM signal

    The problem with your simple flyback converter is we simply cannot see it. Please post a schematic and tell us where exactly the waveform is being checked.

    Brian.
  25. Closed: Re: Where to get schematics about SCRs full-wave triggering circuits ?

    'Ground' in a simulation means the reference point that everything is measured from, it doesn't have to be a connection to the Earth beneath your feet.

    There is no issue with placing the load in...
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