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  1. Replies
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    The design of the E-I lamination and coils makes...

    The design of the E-I lamination and coils makes the magnetic field run along the length of the center leg of the E, then return through the outer legs of the E. Think of the field orientation as a...
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    Were you measuring your 400V at the first...

    Were you measuring your 400V at the first 22uF/450 or the second one?

    I guess, put another way, what are the current (sorry, meaning now) voltages on both caps.

    If the event opened the OT...
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    A transformer with 750ac across a ct high voltage...

    A transformer with 750ac across a ct high voltage output makes 375vac on each half secondary to be rectified. The UNLOADED voltage when rectified is 530Vdc peak, which agrees well with your 513...
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    There is one more step in the humdinger...

    There is one more step in the humdinger evolution. I'd have to go looking for where I saw this, but it was clever.

    There may be some level of hum you just can't get rid of by reasonable means....
  5. First, get that shorted speaker out of there....

    First, get that shorted speaker out of there. These amps don't have any clear protection against shorted outputs, and you could melt down the output transistors pretty easily. In fact, you have...
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    If you're going for the "artificial center tap",...

    If you're going for the "artificial center tap", yes, that works. Two 100R resistors in series, across the whole 6.3V winding, with the center connection between the two resistors tied to ground. The...
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    813

    I'm still a little confused by the question, but...

    I'm still a little confused by the question, but maybe I can add some useful data.

    Is what you're thinking about an attempt to get lower hum? If so:
    > You have to have some kind of reference...
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    Yeah, give them a try. You're actuallyl buying...

    Yeah, give them a try. You're actuallyl buying Newark's assurance that these are quality devices. I trust Newark that much.

    @juan:
    Yeah, they were intended to replace TO-66s. I suspect that...
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    The "has spare capacity" on a 5V winding might be...

    The "has spare capacity" on a 5V winding might be a problem. If the 5V winding is powering a tube rectifier, nearly all tube rectifiers have the cathode connected to the heater. It floats on B+ in...
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    Wow! They're still around! Neat. I was...

    Wow! They're still around! Neat.

    I was expecting him to find a few on ebay for $50 each. I did a few amps early on with 40409/40410, and fixed a few others. The industry zoomed right past that...
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    Add to or mess with the values on the Zobel....

    Add to or mess with the values on the Zobel. Can't hurt, can it?
  12. Replies
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    Possible? Sure. You'll run into several...

    Possible? Sure. You'll run into several difficulties, all of which are relatively well known. There are solutions for them, though.

    The 6.3V/3A winding can be full wave rectified into 6.3V*1.1414...
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    Oh. If the drivers are the 40409/40410 types and...

    Oh. If the drivers are the 40409/40410 types and are damaged, don't even try to get exact replacements. The combination TO-39 device and pressed on heat sink are unique. Count on using TO-220 devices...
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    The amp uses +/- 40V power supplies, total of...

    The amp uses +/- 40V power supplies, total of 80V. Use devices rated for at least twice that, 160V, preferably more.

    A good, safe choice would be the On Semi MJ15022 or MJ15024. There are others....
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    Good for you. Your riddles are Mother Nature's...

    Good for you. Your riddles are Mother Nature's way of telling you that you would really, really enjoy some more electronics learning. Go for it! A few answers to questions in a forum won't do the...
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    The picture of caps mounted up high on springy...

    The picture of caps mounted up high on springy leads over a built-in capacitor roaster resistor is about as bad a way to mount them as I can think of. The failure rate ought to be high on that. The...
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    It seems to be "My amp blows fuses! What could...

    It seems to be "My amp blows fuses! What could POSSIBLY be wrong with it??" season again. I just typed much of this in at another forum beset with "fuses-blowing" problems, so I'll try to reconstruct...
  18. Thread: DC DC converter

    by R.G.
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    @ Soulfetish: Good thoughts. Doing a good...

    @ Soulfetish:
    Good thoughts. Doing a good design of a high frequency switching converter does require a lot of picky considerations. Especially where to get small size, you run your switching...
  19. Thread: DC DC converter

    by R.G.
    Replies
    16
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    511

    How does the ripple voltage react to loading? ...

    How does the ripple voltage react to loading?

    Many recent switching controllers react to too-small loading by going into "hiccup" mode, running a blast of pumping to raise the output voltage,...
  20. Thread: DC DC converter

    by R.G.
    Replies
    16
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    511

    30-40v sawtooth ripple? What frequency is the...

    30-40v sawtooth ripple? What frequency is the ripple?
  21. Thread: PCB grounding

    by R.G.
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    Ah, grounding. :) For your limited case, it...

    Ah, grounding. :)

    For your limited case, it will probably not matter.

    At audio frequencies, what matters in grounding is what >ground offset voltages< are generated by >ground currents<...
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    Do what the high power radio guys used to do: put...

    Do what the high power radio guys used to do: put a load resistor into a can of oil. Drive it with the output signal and the measure the temperature rise of the can of oil. This is probably best done...
  23. Good advice, all. It's all about gluing sawdust...

    Good advice, all. It's all about gluing sawdust together with an adhesive. There are better and worse adhesives for a variety of conditions.

    For wood in dry conditions, ordinary carpenter's glue...
  24. Yes, what he said on stacking. Plus - there are a...

    Yes, what he said on stacking. Plus - there are a number of different stacking patterns that were (and maybe still are) used in transformers, for different effects. It's not just a binary decision to...
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    There aren't any pictures of that board. I can...

    There aren't any pictures of that board. I can put up some pics of the bare board, but my amp tech friend coaxed me out of the first-article assembled item. I'm have to assemble another one to get a...
  26. Stacking the laminations is fairly trivial....

    Stacking the laminations is fairly trivial. Obtaining new laminations in the first place is the trouble. If you can get new lams, you can stack a core in a few minutes. You just start inserting the...
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    I did a little poking through the archives. No...

    I did a little poking through the archives. No luck. It must be the bass 50 I remember.

    But I did come up with some thoughts. Both the US and UK Vox folks liked to do mix and match designs. I...
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    That's reasonable. Another approach would be to...

    That's reasonable. Another approach would be to make and use a light bulb limiter, which is a simpler way from keeping the whole amplifier on a power budget.

    Removing the outputs to eliminate the...
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