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  1. HarryA1

    Oscilloscope Bandwidth ?

    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...
  2. HarryA1

    250 uufd?

    "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...
  3. HarryA1

    Short Circuit protection Using Relay

    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...
  4. HarryA1

    250 uufd?

    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      ...
  5. HarryA1

    0-30V 0-3A Latest Data

    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...
  6. HarryA1

    TDA8512J, any other part that can replace this one ?

    At the bottom of this page is a TDA7387EPAG that you could look at. Plus 53 more pages! https://www.mouser.com/Search/Refine?N=7508787+4292906361&FS=True  Good luck.  
  7. HarryA1

    Audio Amplifier project help

    A search on the internet will yield numerous sites with information on class AB power amplifiers. Like: https://www.electronics-tutorials.ws/amplifier/class-ab-amplifier.html That method of  implementing a class  D amplifier is beyond me.
  8. HarryA1

    18v charger

    Most likely there is a shot within the transformer windings.  You may be able to unwind some of the wire and find the shorted section and repair it. Search for transformer windings on YouTube for insight into transformers. Like: https://www.youtube.com/watch?v=mXFuVHkY8aA  for example.
  9. HarryA1

    12 volt under voltage controller wiring

    That seems like a good idea. I gather that such refrigerators draw something like 5 to 7 amperes. A relay could handle that; such as...
  10. HarryA1

    Arduino rf communication

    If you search on amazon.com for "arduino rf" you will find various transmitter - receiver options. Like this for example&gt...
  11. HarryA1

    spam prevention?

    Congratulations!  Looks like you got read of the bad guys 😊
  12. HarryA1

    Ideas for low quiescent current high voltage charging circuit

    Consider using this:  "DC-DC Converter 3V-5V Output Step Up Step down Buck Boost 300V-1200V PSU Module"...
  13. HarryA1

    Need help with using a transistor or triac as a switch

    Lets see if this is readable. Using a 2n2222 - about 10 cents apiece. Current from the source is 40ma with a base resistor of 1000 or 10k. In the view the yellow trace is the current through the relay; scale on the right . Green is the voltage at the base; scale on the left. I  have no idea...
  14. HarryA1

    About the "50V – 10A BIDIRECTIONAL DC MOTOR DRIVER USING A3941" issue

    from: http://static6.arrow.com/aropdfconversion/ee14f7b4a3764f5a2d5bf5d73381b76d11c173d/3a3941-datasheet.pdf.pdf
  15. HarryA1

    Circuito (Medición de variables)

    Medición de variables electricas modelo #2  (Measurement of electric variables model # 2) ¿Qué es el modelo # 2?  (What is model #2 ?)
  16. HarryA1

    Phase Dimmer Control using Triac

    I believe your circuit is not quite correct. The resistor and capacitor (C1 and R3 ?)  belong to the DIAC not the TRIAC. see the circuit here:  https://www.electronicshub.org/simple-fan-regulator-circuit/
  17. HarryA1

    Sine wave frequency multiplier

    That is a good idea but how do you get the divide by 2.7 required ? Is the best one can do is to  divide by 5 then by 2  or 10 and 4 for 2.5 perhaps. There is a good phase locked loop frequency multiplier tutorial at: www.youtube.com/watch?v=5by0os8RrFY
  18. HarryA1

    Sine wave frequency multiplier

    The only way I can think of to do that is to  use two circuits. First a frequency to voltage converter circuit. Then feed the voltage output of that circuit into a voltage to frequency converter circuit.   One can find such circuits by searching on the internet.  A circuit simulator would be...
  19. HarryA1

    Ratio Detector

    The vertical green line supplies current to the transistor. The other part of the  green line supplies  current to the detector which modulates it to form the audio and afc outputs.
  20. HarryA1

    spam prevention?

    On my forum if you replace http: and keto one can at least alert guests not to click on the links and that may help. At least it is  not difficult to implement. from my forum (note spaces around SPAM and SPAMMER - helps  them stand out): Put the word to be censored on the left, and what to...
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