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About UFN

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  1. 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).
  2. 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.
  3. Looks good. I don't really need more headphone amps, but do you have any spare boards? 😂
  4. 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
  5. The pot model is called an Alps RK16812.
  6. UFN


    I have a YM 16622 which I bought app. 10 years and it's probably the most versatile watch that I have owned. The grey/neutral/understated look pretty much suits whatever else you are wearing and it means you can just put it on and forget about it. I've also worn it for a whole summer on a Nato-strap (grey/navy) and that worked really well also IMHO - and the funny thing was that very few people recognised it as a Rolex that way (but the few that did normally struck up some interesting watch-geek conversation afterwards ).
  7. Seeed should do the same as well (or thereabouts)
  8. Had a Weller Pyropen Piezo years ago and liked it for a couple of things. One was soldering stuff in other places than my desk where I couldn't be bothered to get the soldering iron and an extension cord. The other was soldering thick speaker cables to drivers/crossovers where I needed more heat than my stationary iron could provide. For electrician-type soldering and heat shrink it's probably fine, but I wouldn't use it for electronics. Not only because of the crude temperature control but also because then ones I have seen all seem to eject (very) hot air off to one side. Realistically it's only a matter of time before you turn the iron in a way that means the hot air will damage a board or some parts.
  9. I have seen the same used on discrete power amps with a thick and "spongy" thermal pad on the bar to even out the differences in thickness. Then it was possible to clamp e.g. both Sanken MT200 power transistors and TO-220 VAS transistors with the same bar. I would think that's fine. It also puts the clamping force directly on the body of the device and not on the flange, so there should be less risk of having devices that aren't completely flat against the heat sink (which would lead to thermal instability).
  10. UFN


    Difficult to see from the pics how much space you really have, but FWIW this layout would probably be my starting point.
  11. 2 Oz boards tend to be a little more tolerant if you need to replace components because the traces will take a bit more heat. Thick 3 Oz traces may actually require more heat than you usually need to get good joints and make the boards seem difficult to solder, so if you don't need the high current I wouldn't bother with that (they also tend to be much more expensive).
  12. I used Pana FMs on at least one of mine. Mouser p/n 667-EEU-FM1V102 is the right size as I recall (1000uF/35V ø12x25)
  13. I have never seen any, but that doesn't mean they don't exist. I would be doubtful though - Neutrik makes the blanking plates because you can get pre-punched 19" rack panels for Neutrik D-series jacks where there may be more holes than you need and so the blanking plates are handy for keeping dust out etc.. I can't imagine many cases where there are many more IEC-holes in an enclosure than you need ?
  14. Looks like someones been digging in Kevin's archive again ? Carbon Megatron
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