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Recent content by larry_walker

  1. L

    CJMCU-9833 english manual needed

    Hi FvM, Thanks for the answer, now I think the AD9833 datasheet will suffice. Do you know what does the REF pin?
  2. L

    CJMCU-9833 english manual needed

    Hi all, I've had (for a very good price) an oscillator CJMCU-9833 based on AD9833. All the sellers on the I-net provide the same Baidu link, as the address of the manual. Needless to say: I cannot download this manual. My question is: could someone, please, send me the manual for this module...
  3. L

    Opto Switch Reversing

    Hi Englewood, As far as I see on your breadboard, the emitter and collector are not wired correctly (inversion). Maybe I am wrong, but I think you should check with the data-sheet: https://pdf.datasheetcatalog.com/datasheets2/33/339733_1.pdf
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    [SOLVED] Motor mosfet problem

    Hi. If you allow me a suggestion, I think you may obtain a better result with an opto(de)cupler MOC3021, followed by a triac BTA20 600B (if the opto(de)cupler current does not suffice). You can buy those on E-bay or Aliexpress for less than $5. Here you have the links for the data-sheets...
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    [moved] how to calculate a push-pull amplifier with transistors

    Hi guys, I have a very stupid question, the kind only a beginner could ask (sorry for wasting your time). Believe you me, if I had found this kind of information on Google, I wouldn't bother you. I want to learn how to calculate an amplifier form a data-sheet. Could someone point me to some...
  6. L

    TCP /IP problem when connected with self made server

    Can you connect to the IPv6 address of the server, from the 3G connected devices (your project and your phone)? Can you disable temporary the IPv6 protocol on your server?
  7. L

    buck boost/step up ? battery to constant 18v

    Hi, As far as I understood your problem, I think you need a voltage regulator. If so, you should take a look to an LM78XX (LM7805 for example). Cheers.
  8. L

    TCP /IP problem when connected with self made server

    Hi, Sounds to me like a "classical" connectivity problem. Question : can you "ping" the machine running your server (in your mock IPv4 address : 103.234.27.54), form another 3G connected device (i.e. your phone)? If so, I have no answer. Else, I think you should expose your server's machine to...
  9. L

    how to build an ultrasonic generator

    Thank you so much Klaus. I think this is the solution !!! I found an integrated circuit that looks very promising : ALD2701. As soon as I built the device, I will provide feedback and mark it "solved" (it may take some time).
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    how to build an ultrasonic generator

    Hi Brian, I try to build an ultrasonic generator, with (no harmful) high frequencies. Those frequencies are supposed to be unpleasant for animals. The device I bought is a "Horn tweeter", thus a resonance frequency do not apply. I will use it to protect my car against animals. I live near a...
  11. L

    Designing an comparator from op-amps like lm386 or ua741

    Personally, I would consider to use an Arduino Nano (it cost $1.45 on some well known commercial sites). If you look for "New Pro Mini atmega328 Board 5V 16M Arduino Compatible Nano NEW M43" you might find what you need.
  12. L

    how to build an ultrasonic generator

    Partially solved : how to build an ultrasonic generator Hi again, I found (on some well known commercial websites) the following circuit: NE555 Pulse Frequency Duty Cycle Adjustable Square Wave Signal Generator HC See img1.png I suppose the schematics is, more or less, like in the img2.png...
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    how to build an ultrasonic generator

    Hi friends, I bought an ultrasonic transmitter, with no model number. The only reference I have is : ultrasonic speaker 38mm horn. In the specifications, I found that it works for frequencies between 9 khz and 46 khz (yes, I'm as astonished as you are). My problem is that I do not know how to...
  14. L

    Can sound be focused like a laser?

    Hi, I think it would be useful to take a look at the AcuSpaDe product. https://www.ultrasonic-audio.com/products/acouspade.html Cheers.

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