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UFN

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About UFN

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  1. Are the pin connections correct?. Most of the fake 2SK216s are remarked devices and they don't have the same pinout. Not a guarantee, but a strong indication.
  2. Just a bit more, at around 1 kW per box into 4 ohms...
  3. I was starting to think that this project would require one of these: I know it's not a Festool, but I think you might be able to scrape by with Mafell
  4. Agree with that. What makes you think that all these component replacements are in fact improvements?
  5. Not needed here because the offset is trimmable here - it wasn't on the original Dynalo.
  6. Two comments to the BoM: - Your LEDs are listed with a 2.1V drop. As Pars mentioned higher up in the thread you should normally use 1.7V for Kevin's designs (LTL-307ELC) - Can't remember the spacing for the 5pF capacitors, but I believe I used a high-voltage ceramic (75-561R10TCCV50) for this (also for the dynalo, although my boards are a different version).
  7. UFN

    kgst

    Isolated semis you normally just mount with a bit of thermal compound between the package and the heatsink and a metal screw. That's the benefit of the full-isolated package - faster mounting (the downside is poorer thermal performance compared to a regular TO-220).
  8. I have boards but I haven't put them together yet. Can you just switch between ZF and SS, aren't the component values and placements different so that you have to choose a configuration up front?
  9. The plaque on the back should say "No actual knowledge involved in building this device" or something like that....
  10. IME yes the 2SC4686s have very low hFE. The last batch I bought all measured 22 and to be honest I thought the tester was broken until I checked the data sheet and saw that this is actually with specs (albeit at the low end).
  11. Yes, that's perfect. The 4M7 resistor on the bias out means that your meter will load down the bias voltage if you measure there. The test point is added before the resistor so you can measure the actual voltage accurately.
  12. Looks good. I don't really need more headphone amps, but do you have any spare boards? 😂
  13. A toroid transformer that's audibly humming is normally either badly made, overloaded or miswired. Does it hum without load as well? Also, you do know about shorted turns on toroids, right? https://www.bicronusa.com/resources/tech-guide-toroidal-power-transformers
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