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  1. bertus

    SMPS analysis

    Hello, The drawing I made is for a shorted D812. The short could blow R840 or the fuse. It could be that R840 is a fusible resistor. Bertus
  2. bertus

    SMPS analysis

    Hello, It will short in input at the positive phase: Bertus
  3. bertus

    Experiment with NPN transistor BC547

    Hello, That should work fine. The base current is limited by the 1K resistor. The led is protected by the 470 Ohms resistor. Bertus
  4. bertus

    Making the connection

    Hello, An other great brand for removable connections is the Anderson Powerpole series: https://en.wikipedia.org/wiki/Anderson_Powerpole https://www.andersonpower.com/shop/wire-to-wire/powerpole.html Bertus
  5. bertus

    How to connect piezo speakers to an amplifier

    Hello, For the cables, have a look at this article: https://sound-au.com/cables.htm There are 6 pages with info. Use the next button on the bottom or the links in the menu. Bertus
  6. bertus

    Experiment with NPN transistor BC547

    Hello, No, the led is protected by the 470 Ohms current limiting resistor. The transistor can be dameged by a to large base current. When you put a resistor of 1K between the top of the potentiometer and the +5 Volts, the transistor is protected from a to high base current. Bertus
  7. bertus

    Experiment with NPN transistor BC547

    Hello, If you want to make better looking schematics, you can copy paste symbols from this sheet into your schematic drawing: Your schematic could look like this: Bertus
  8. bertus

    48V.

    Hello, The +48 Volts is 48 volts positive related to ground potential. The -48 Volts is 48 Volts negative related to ground potential. Bertus
  9. bertus

    Experiment with NPN transistor BC547

    Hello, You can test the transistor with a multimeter: https://www.electronics-notes.com/articles/test-methods/meters/multimeter-diode-transistor-test.php https://allabouteng.com/how-to-transistor-test/ When using a digital multimeter, you can use the diode test function. Bertus
  10. bertus

    Experiment with NPN transistor BC547

    Hello, I hope you did not turn the potmeter fully to the +5 Volts. If you did so, the transistor might not have survived the action and got burned out. The base current may not exceed 20 mA. Bertus
  11. bertus

    Experiment with NPN transistor BC547

    Hello, Can you post a schematic, in stead of the breadboard? Schematics are the universal electronic language. Bertus
  12. bertus

    Problem with data logging in arduino environment

    Hello, Are the signals at TTL level or at RS232 level? https://en.wikipedia.org/wiki/RS-232 Are the levels matching? Bertus
  13. bertus

    Paperwork for AVO two piece valve tester.

    Hello, When you are looking for tube data, have a look at my resource: Vintage info from the days of vacuum tubes Bertus
  14. bertus

    Powering 0402 smd LEDs

    Hello, Under the replybox, you will find a button with "Upload a File" on it. With that button, you can upload photos and PDF's. The photo should be resized to about 300 kB. You should be fine then. Bertus
  15. bertus

    Powering 0402 smd LEDs

    Hello, Just another question. How will the leds be arranged? Inline, circle or bow? Could you make a sketch? Then we can likely make suggestions how to mount them. Bertus
  16. bertus

    Comedy Thread

    Do you also like cheese fondue? This chinese guy has some difficulty with it:
  17. bertus

    Paperwork for AVO two piece valve tester.

    Hello, You might find it on this jabse page: http://www.jabse.com/Ly4gUmFyZSBhbmQgQW5jaWVudCBFcXVpcG1lbnQvQVZP You can download the correct one when you know the model number. Bertus
  18. bertus

    Powering 0402 smd LEDs

    Hello, Did you read the resource that @Harald Kapp gave you: "Got a question about driving LEDs?" In there you will find this picture on leds in parallel: As you can see each led has its own resistor. As you are using different colors of leds, the resistors will have different values. Bertus
  19. bertus

    Sony ICD-PX240 voice recorder button not working

    Hello,, What is the actual size of the buttons? They look like they are mounted on the PCB. These on ebay look a lot like them: https://www.ebay.com/itm/4x4x0-8mm-PCB-Surface-Mount-Tactile-Membrane-SPST-Switches-SMT-SMD-Push-Button-/254176114146 Bertus
  20. bertus

    Making the connection

    Hello, Soldering the wires together will make a permanent connection. You could use heat shrink tubing for isolation. You even can get heat shrink tubing with glue inside to make it water tight. When you want to have a removable connection, the connectors the TS used can be used. In that case...
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