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Posts posted by HarryA

  1. 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 helpful here.

    The 9400 chip can be used as a voltage-to-frequency or frequency-to-voltage converter. Perhaps there is a newer chip?

    Hopefully someone else will have a better idea for you 😐

  2. 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 change it to on the right.

    http:  =>  SPAM
    KETO   =>  SPAMMER

    given:  http://www.badguy.com =>  SPAM //www.badguy.com
               this is keto crap     =>  this is  SPAMMER  crap

    Members posting url's in a post would learn to use the short version without the http: www.rcgroups.com


    Is spam the correct word or does that only apply to emails?


  3. If you open the register page and right click on the page and select "view page source" you see the html code that makes that page. If you search on that code for: "form_q_and_a" you will find the block of code that renders that area on the page.(in firefox search by ctrl+ f) and that contains your question. If one is comfortable with working with files on the server one can find the file that contains the "form_q_and_a" string. then download it to your pc and replace the text string with an image ( jpg or png file ) of the text in mixed colors and fonts.

    If you don't have the tools to create such a file I do. You may not see you  text string  in that file as  it maybe added in at run time.

    In my first forum I got to the point that I would register members via an email request myself; they where not allowed to do so. I used their requested user name and assigned them temp.password and that works well if you do not have many request per day. It beats having to clean up the forum everyday.



  4. To start with those capacitors are 4700 microfarads (not 4.7) at 400 volts, not cheap. The resistors are 50 watt resistors.

    I would think the yellow leads on your transformers are taps, here unused. If you connect two of the output black wires together and measure the voltage across the other two you should get 220 volts rms. If not select a different wire for one of then. You must have at least a   inexpensive multi-meter to work with.

    Beware these are high voltages and those large capacitors hold enough current to do you in!

  5. Something like what is the:  "unit of capacitance"a five letter word". It is only a slight inconvenience at most for real people plus they only have to do it once.

    I set up a forum earlier this year and asked the local padding group if they wanted to use it but they decline. I did not do anything with it for a few months until I got an error message via an email. When I looked at it I had 6800 members, 90% were Russian. As I could only delete 30 members at a time it took awhile to get rid of them. 

  6. Hello, You could use a rs232 to ttl  converter  that you could connect to an Arduino microprocessor, You can get the converter for 1$, Arduino from 10$ to 30$ depending on the quality you want. Also you need a power supply about 10$ and a relay about 5$,  Plus connectors.

    see: https://daverobertson63.wordpress.com/2013/06/02/serial-port-mini-rs232-to-ttl-converter-adaptor-module-board-max3232-with-arduino/

    Many of us can help you with the software.  I just got a large memory Arduino for 10$ that I am using for a talking weather station.

  7. If you look around on ebay or amazon.com for "audio amplifier board 5 volts" you may find something that would be helpful. Like:

    Icstation PM2038 2X5W stero audio amplifier board 5v USB powered adjustable volume. They are quite inexpensive.


    Sorry I can not be more helpful.

  8. Perhaps the chip is over heating with to much current draw?  Try connecting only two motors to see what happens.

    For the l298n chip itself:

    For the IO Peak Output Current (each Channel)       
    – Non Repetitive (t = 100ms)            3.0A
    –Repetitive (80% on –20% off; ton = 10ms)    2.5A
    –DC Operation                    2.0A


  9. if:
    Vp = primary voltage, Ip =primary current, Np = number of primary windings.
    Vs = secondary voltage, Is = secondary current, Ns = number of secondary winding.

    then: Vp = Vs(Ns/Np)  and Ip = Is(Ns/Np)

    example: To transform 120 vac to 12 vac,  
    Vs = 120 vac (100/1000) = 12 vac Ns/Np = 0.1, say 100/1000

    Using Ip = Is(Ns/Np)  I am not clear which way you are going here.
        0.3 amperes = 1 ampere (Ns/Np)  Ns/Np = 0.3  say 180/600
    or:      1 ampere  = 0.3(Np/Ns)     Np/Ns = 3.33..    or say 600/180

    For power: Pp = Ps  at 100% efficiency.
    Ps = n * Pp where n is the efficiency factor. n between  65 and 99 percent

    For 50 watts at the secondary and 75% efficiency the primary power would be:
    Pp watts= Ps/n = 50 vac/0.75 = 66.66... watts.

    For Impedance: Zp = Zs(Np/Ns)^2

    To connect an 8 ohm speaker to a 400 ohm amplifier:
    Np/Ns = (Zp/Zs)^0.5 = (400/8)^0.5 =  7

    I must confess I have no idea how many windings real transformers have; do not go by my numbers.

    Somewhere I have a book that has information on designing transformers if you need more info I will try to find it.





  10. I would think if the larger rated relays failed then the smaller rated relays would not last as long.

    Have you tried looking on Ebay for replacements? I have had good luck recently finding replacement  parts on Ebay.

    Sorry I can not be more helpful to you; good luck.

  11. At the lower left the component would be a 1500/1k5 resistor like the one at the lower right.

    The LEDs indicate which coil/output is active. At the upper right the symbol looks like a ground off the signal generator.

    The LEDs are represented  by the white dots on the front panel above the words OUT  perhaps?

    P1 and P2 look odd; they have the potential of shorting the inputs. At P2 with the wiper all the way down the input would be shorted circuited.


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