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  1. bertus

    What are these?

    Hello, Reduce the size of the pictures to about 300 kB and you are able to post the pictures. Bertus
  2. bertus

    FET question

    Hello, Most info and tutorials are related to the N-mosfets. I have attached three of those documents. Bristolwatch has a tutorial page that uses P-mosfets: http://www.bristolwatch.com/ele/tr1.htm I have also added a list of P-mosfets in the PDF. (XLS and ODS , the spreadsheet formats, are...
  3. bertus

    FET question

    Hello, The diode is part of the construction. Read this wiki page and look for the body diode: https://en.wikipedia.org/wiki/Power_MOSFET Bertus
  4. bertus

    A few questions about the allocation of frequencies

    Hello, There are a number of types of communication below 9 kHz. Have a look a these wiki pages: https://en.wikipedia.org/wiki/Radio_spectrum 3–30 Hz, 100,000–10,000 km : Communication with submarines 30–300 Hz, 10,000–1,000 km : Communication with submarines 300–3,000 Hz, 1,000–100 km ...
  5. bertus

    Voltage Drop after optocoupler.

    Hello, Check the value of R1. Is it really 270 k? Change it to 270 Ohms and try again. Bertus
  6. bertus

    Radio

    @davenn , I know those. They are used as tuned circuits for the oscillator, IF (Intermediate Frequency) and detector circuits. TOKO and MURATA are well known brands for them. An example of the connections: In an AM radio you can possibly find these coils: Here is an other page with info...
  7. bertus

    Radio

    Hello, What do you mean with variable inductor? In a radio there is a tuning capacitor. https://www.petervis.com/electronics/tuning-capacitor/tuning-capacitor.html Bertus
  8. bertus

    ODU not transmitting

    Hello, From the AAC : Out Door Unit for microwave transimission Microwave is not a simple technique. The Internet Archive has a couple of Design books: https://archive.org/details/microwaveandrfdesignvolume1radiosystemsthirdedition...
  9. bertus

    ODU not transmitting

    Hello, @davenn , The user also has a thread running at All About Circuits: ODU Transmission failing Bertus
  10. bertus

    Samsung LE40B530P7W - NO POWER - BN44-00264C Rev 1.4 fault find

    Hello, It sound as if there are still parts that create shorts. It can be that some mosfets in the SMPS are bad. Unfortunately the service manual does not have any schematics. As for power checks it has the attached pages. Bertus
  11. bertus

    Replacement pcb mount nicd battery

    Hello, I think that this battery will come close: https://www.newark.com/varta/55625603059/nickel-metal-hydride-nimh-battery/dp/68C4944 Bertus
  12. bertus

    technics digital piano

    Hello, Have a look here: https://elektrotanya.com/technics_sx-px111.pdf/download.html Bertus
  13. bertus

    Diode 1N2007

    Hello, @Harald Kapp , You are right, I have added the remark line at the picture: Use a matched set to achieve voltage rating. It looks like that 4 times 1N5280 in series are needed. Bertus
  14. bertus

    Diode 1N2007

    Hello, The 1N5280 seems to be out of stock, but there are other 190 Volts zeners available: https://www.digikey.com/en/products/filter/diodes-zener-single/287?s=N4IgjCBcoJwEwAYqgMZQGYEMA2BnApgDQgD2UA2uDAgAQBqIAusQA4AuUIAqgHYCWbAPLoAsvky4ArgCd8IAL7EAtHGQg0kNtMlFSFEAFYm8k0A Bertus
  15. bertus

    Diode 1N2007

    Hello, An 1N5280B seems to be a replacement: Added remark line at picture Bertus
  16. bertus

    Diode 1N2007

    Hello, Is this the diode? https://www.web-bcs.com/diode/dz/1n/1N2007.php Added some pages where the zener is mentioned. Bertus
  17. bertus

    Boosting the Amper and altering the frequency

    Hello, It could well be an 1 Watt zener diode: 1 Watt zener diode Where did you buy the zener? On ebay , alibaba , aliexpress and amazon you can not be sure to get a genuine part. Many fakes are around on those sites. Bertus
  18. bertus

    Boosting the Amper and altering the frequency

    Hello, How did you connect the multimeter for current measurement? For current measurement the multimeter should be in series with the device from wich the current should be measured. Bertus
  19. bertus

    Boosting the Amper and altering the frequency

    Hello, It is strange that the zener burns. There must be a to high current, but I can not see from where. You could boost the zener with an extra transistor and resistor as in the following link: https://sound-au.com/appnotes/an007.htm Bertus
  20. bertus

    Boosting the Amper and altering the frequency

    Hello, What is the type number of the zener diode? It more looks like an 400 mW version. Bertus
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