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Posts posted by HarryA

  1. That sounds like a major project. One would want to use a microcomputer as it would  simplify the circuitry greatly.

    Example: https://www.youtube.com/watch?v=9IWWa0xCd04&feature=emb_logo

    It is said that power supplies are less expensive today for EDM machines, perhaps you could search on the internet for a good price. I would thing that 2950 pounds is expensive:


    I have an eight inch steel disk that I want to make a 100 tooth sprocket from - an electrical discharge machining would be great for that I would think.


  2. I would think that is a good solution. A more elegant solution would be to use a temperature control switch in series with the fan. They are not very expensive.  You want one for example: less than 25 degrees normally open and higher than 25 degrees normally closed.


    The admin fixed the ugly url - looks a lot better 😀



  3. By pads do you mean the pads (marked hall) on the lower right of the board? If so knowing any dimension on the board, like a component, one can find other dimensions using a tool like photoshop or the poor man's version THE GIMP.

    Also knowing the board is 63x42.5x17 mm (L*W*H) one could scale it off the screen.

    this thing will not go away

     delete yourself !

    Also there is a manual in English here but the link is broken - you may request one perhaps.



  4. There is an old rule that you need  at least 2 times the frequency that you wish to view.

    There is a publication by the ARRL "Oscilloscopes for Radio Amateurs". On Amazon.com is near 20$ used or about 10$ for the kindle version that maybe helpful. The kindle version can  be viewed via their free PC app.

    Also  there are  videos on YouTube on choosing an oscilloscopes. I have a Hantek DSO5202P it was far more functionality then I need. I did have to replace the display after about three years but they are not expensive.

    37 minutes ago, mc1822d said:

    40 views and no advice? 😭

    The problem I have is that I answer so many questions that I like to give others a chance to  answer some.  But that is not always helpful I know. 🤨



  5. "Micromicrofarad" or "micro-microfarad" is an obsolete unit found in some older texts and labels, contains a nonstandard metric double prefix. It is exactly equivalent to a picofarad (pF). It is abbreviated μμF, uuF, or (confusingly) "mmf", "MMF", or "MMFD".

    A microfarad is 10 to the -6 so a micromicrofarad is 10 to the -12  =  picofarad

    from: https://en.wikipedia.org/wiki/Farad

    Good luck with your radio. I  repaired lots of radios years ago. I wish I had some of the old radios I cut up for parts. I still like tubes!

  6. I would think that when you push the button nothing will happen as the NO (normally open) contacts block the flow of current through the coil of the relay.

    Are you looking for a 12 volt circuit breaker?  Like https://www.ebay.com/itm/12V-24V-DC-HOME-SOLAR-SYSTEM-WATERPROOF-CIRCUIT-BREAKER-RESET-FUSE-INVERTER-USA/153563481272?_trkparms=ispr%3D1&hash=item23c118c4b8:m:mmcjUEQXbNT08tOydOyNxXQ&enc=AQAEAAACUBPxNw%2BVj6nta7CKEs3N0qXpeqhE5Yqs%2B5LvC9kXWBRLunj104AP1sk21at2FZKc2iKh6XL47x1FcO%2BWWY7Rimprmp3h7zN%2FF8RD1a7w7vzGGJeb9L2sR7f6jp3cjblM8ffcC%2FyCeSoSY8lAMKJbUhQ6S8M8LOVbw3gcZrpihnlCk8ERij6l3ii4IEdrt7BTr1HND0HLVDYB85tX0TxWMy4Wq6kO2e4c9S4%2BWinS6pDUakuP3j%2BpaX9BttfII9rjI7xjJnj%2B%2F3fVaA4a9eY03U4A24FUFMwuTrhjRN0WLjdVHVfES9TarXp1Nqr9%2FRtAXJuBcYPC%2FTW7Q4jbkyOcegtOw9dtKtyl9KgHUA6lvz%2FPAcb9QjLahlUE%2BG31z1JrEmfsOmbfmjGGNP0pKGeb9kleHNWuDkMjTGwqsKXQn6yLqiiUhVjtnJ1xTFJKYKD703LIVwIEkfYMIk%2FtNglIpTR%2BzjMcKI6QxGd%2FKD%2FTqOj0lLtOorDfKFUcIeO1%2F0j8LHZO3Yua4YlExNsiHhanZag6MIt5MVTb%2FU4hbfIhgqewz8q06ycP32xVpMz6d4tWdBQN4EKPtPGmU0PnWtCTGZ7aDEuFoPYYG%2FIr5jDaWLGQj30RndKgD7T3H%2FtNskrUCcD7Ypi7UdAOQiNOQ6wvFjlCWz%2BU1X1a4r%2F6ECOOJznNxsK9%2BdtjhS9mbWZcgR7UpoDXiS%2FkqcY1kL9ZVfYgpSoe4z5egyor4y3LYbs1taDt%2B5g84KV8oMwjE6SA60lmeO%2BzHpPjDMrm4SYeGZhi1c0%3D&checksum=15356348127258f693ad8dc343969d0a485f272220a5&enc=AQAEAAACUBPxNw%2BVj6nta7CKEs3N0qXpeqhE5Yqs%2B5LvC9kXWBRLunj104AP1sk21at2FZKc2iKh6XL47x1FcO%2BWWY7Rimprmp3h7zN%2FF8RD1a7w7vzGGJeb9L2sR7f6jp3cjblM8ffcC%2FyCeSoSY8lAMKJbUhQ6S8M8LOVbw3gcZrpihnlCk8ERij6l3ii4IEdrt7BTr1HND0HLVDYB85tX0TxWMy4Wq6kO2e4c9S4%2BWinS6pDUakuP3j%2BpaX9BttfII9rjI7xjJnj%2B%2F3fVaA4a9eY03U4A24FUFMwuTrhjRN0WLjdVHVfES9TarXp1Nqr9%2FRtAXJuBcYPC%2FTW7Q4jbkyOcegtOw9dtKtyl9KgHUA6lvz%2FPAcb9QjLahlUE%2BG31z1JrEmfsOmbfmjGGNP0pKGeb9kleHNWuDkMjTGwqsKXQn6yLqiiUhVjtnJ1xTFJKYKD703LIVwIEkfYMIk%2FtNglIpTR%2BzjMcKI6QxGd%2FKD%2FTqOj0lLtOorDfKFUcIeO1%2F0j8LHZO3Yua4YlExNsiHhanZag6MIt5MVTb%2FU4hbfIhgqewz8q06ycP32xVpMz6d4tWdBQN4EKPtPGmU0PnWtCTGZ7aDEuFoPYYG%2FIr5jDaWLGQj30RndKgD7T3H%2FtNskrUCcD7Ypi7UdAOQiNOQ6wvFjlCWz%2BU1X1a4r%2F6ECOOJznNxsK9%2BdtjhS9mbWZcgR7UpoDXiS%2FkqcY1kL9ZVfYgpSoe4z5egyor4y3LYbs1taDt%2B5g84KV8oMwjE6SA60lmeO%2BzHpPjDMrm4SYeGZhi1c0%3D&checksum=15356348127258f693ad8dc343969d0a485f272220a5   You don't see a URL like that everyday!

    You could put a relay across  it with a single pole double throw contacts  so that when there is not short you light a green led else a red one.

    How to build a circuit breaker is shown here that could be modified for 12 volt operation if that is your goal.


    Else define what your goal is better.  Good luck.




  7. Capacitor conversion chart / table
    - a capacitor value conversion chart or capacitor conversion table to convert
    capacitor values between
    picofarads (pF),
    nanofarads (nF),
    microfarads (µF)

    Capacitor Conversion Chart
    microfarads (µF)     Nanofarads (nF)     Picofarads (pF)
    0.000001                       0.001              1
    0.00001                         0.01                10
    0.0001                           0.1                  100
    0.001                            1                     1000
    0.01                            10                  10000

    240 pf capacitors are available on ebay



  8. From above:

    Hello, first of all they call me José Silva, (FRISIL). I just registered at Comunidad Electronics-Lab.com.

    I am not a professional in electronics, I am just beginning and with advanced age (55 years).

    I have been watching the development of this source and it has aroused great interest in putting it together.

    I am simulating it in proteus with TL081, I have a question about SetOFF NULL in U2. Does this potentiometer go between pin 1 and 5?


  9. If you search on amazon.com for "arduino rf" you will find various transmitter - receiver options. Like this for example>


    for this model note:

    • T400 Transmission Distance: 400M
    • T400 Receiving Distance: 50M
    • GWB Transmission Distance: 400M
    • GWB Receiving Distance: 400M

    I do not see the differences between the T400 and the GWB units when ordering the units. 

  10. Consider using this:  "DC-DC Converter 3V-5V Output Step Up Step down Buck Boost 300V-1200V PSU Module"


    If one monitored the capacitor voltage so when it got charged the battery was switched off and back on when it got low the average current drain on the battery would be acceptable perhaps.  One could use JFETs and large (mega-ohm resistors) so the drain would be low on the capacitor. The converter would be switched on and off as it charged and recharged the capacitor; so the average current draw would be acceptable.

    Someone who knows JFETs better than I would be helpful here.




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