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  1. Apheared

    Battery pack for Creek OBH-11 ?

    Series: more voltage, same runtime. Parallel: more runtime, same voltage. all those 9V tricks will work, to more or less effect. end result: you still gotta carry the thing, and the battery pack. Stick to your TA.
  2. Apheared

    Confused about opamps on commercial CD player

    Hmm, you'll have to do a bit more reverse engineering than that. It could be some are single amps, some are duals... they look the same unless you know. Might not even be related to the headphone circuit. The easiest way to know is to contact Onkyo for a service manual, which will have a...
  3. Apheared

    Working with SMD devices

    SSOPs. Right at my limit. I can touch the individual pins with the 1mm tip and I only reflow the pins to either side when heating one, and I guess I could be successful. Double the density of SOICs? Ugh. And you like this? Woah. I never thought a one millimeter soldering iron tip would be huge...
  4. Apheared

    Working with SMD devices

    That's great, as an inspection tool... not as a work tool. (probably makes stones look good too, whip out the loupe with a florish and check out the teach's wedding ring!) Like, it'd be GREAT for seeing all the pins bridged together tryin to solder MSOP8 with a 28 gauge wire wrapped around a...
  5. Apheared

    Problem with World Audio HD83

    No, not mono/stereo... but a switch. Those "horseshoes" are only a short with no plug inserted... Divie's right, you were floating the phones ungrounded, by wiring the ground wire to the side that got unswitched when the plug was inserted. Great troubleshooting. I've heard of a few people now...
  6. Apheared

    new website

    While only marginally related (the link is in the gallery section of passdiy) THIS is what I wish I was cool like. THIS is what I would do if I had a garage or basement workshop. I hate speakers... I'm headphones 101% of the time for over a year... but this rig. DIY everything. Check this...
  7. Apheared

    Real Pain In The Amp!!

    No, that's probably not it. If the 'lytics were hosed, then running the amp without em would make it work just fine. You don't need reserve caps when a BUF634 is your rail splitter! If removing them makes it louder, it's probably ground related... they're acting as a filter when in the...
  8. Apheared

    Next amp?

    Ok, so no one has a suggestion for you. Stop bumping it. Do you want portable or AC, glass or solid state? Do you want something that is paint-by-numbers or something where you have to think? Do you want to do math or want the math done for you? Do you want something you can complete in an...
  9. Apheared

    Weak Amp?

    Let the crossposting continue! I answered you at the other place, sorry.
  10. Apheared

    same op amp, different maker?

    Well, that's not entirely true. Sometimes a part is also made by someone else, later in life. But usually the entire part # will be the same, even if it's not their normal nomenclature. Like, many people make LM317-Ts, not just National. Philips uses TDA* for it's amp chips, but you can get...
  11. Apheared

    Way to recognize DIY amp designers

    Forrest Mims the I II III IV? Just Kidding! Why kidding? You know more than him? You have nothing to learn from those books? Hey he's a hero too... he's not a pioneer that I know of, but definately worthy... (just like that generation has a crapload more than just Walt and Bob, I just...
  12. Apheared

    Way to recognize DIY amp designers

    lego, I apologize... I've hihacked your thread. ------ I'm just venting... I don't want the cliffnote version, I actually want to strive for understanding. Do you remember when you finally got your head around the concept that frequency wasn't so much a value as a measure of time? It's...
  13. Apheared

    metal film resistors

    Quote: if I understand your equations correctly, at 18 volts, a 1/8 watt resistor can handle 7 milliamps? ok, but - you are leaving out the resistance for us. 10 ohm @ 18V? 18/10=1.8*18=1800mA*18V=32,400 mW = Smoked. 10k @ 18V? 18/10,000=1.8mA*18=32.4 mW = Fine. And you...
  14. Apheared

    Will portable audio ever get good?

    Also don't forget that there's DVD portables now, even some FINALLY without screens... not intended to be portable audio devices but something that Jimmy can take from dorm to home to his buddy's house easily. We have to keep an eye on these, a great DVD-A portable might just come out, or even...
  15. Apheared

    Way to recognize DIY amp designers

    Budgie: Exactly!! They're just implementors. Most chip builders aren't pioneering, they're using the tools they have to a commercial endevour. They already have the circuit they're just learning how to make it smaller and automated and hopefully cast it on a die to imbed it in your cell phone...
  16. Apheared

    Working with SMD devices

    exactly... SOIC is "surface mount" considering the only other term is "through hole". While no SMDs go thru a hole, they vary in size greatly... re: aos's SOT example if you sneezed on the board while tryin to tack a SOT-23 device, not only will it fly off the board but you'll never find it...
  17. Apheared

    Working with SMD devices

    Eric, you can do it. Just remember there's SMD and then there's SMD. Stay away from stuff that requires a professional assembly station if you don't have one or the skills... you'll just get mad. Remember the first time you saw a DIP and were wondering if your hands were stable enough and...
  18. Apheared

    can my panasonic portable cd player drive a sennheiser?

    your headphones will use more power driven by a 10mW amp than driven by a 5mW amp at the same apparent volume Nope... it could be 105mW or 5mW _capable_ but at the same apparent volume it's a toss-up which will use more current. The quiescent current will be specific to the amplifier chip...
  19. Apheared

    Transformer and diodes burning up

    Tomo, hold tight man... you're mixing two of his things together... the dual rail supply is for his kgilmore, the external single supply is for his 823 2001... that's the one with the buf634 as the virt gnd driver... Now, at the output of the buffer, between V+ and pseudo ground, there's ~8V...
  20. Apheared

    Transformer and diodes burning up

    [ah note to self: post new message when coming back to a thread.] You edited that last response and I didn't know this was done... so what was it? Why did they fry in the first place? Any clue? I mean we kinda know why they did, but any ideas as to what event/when? Initial miswiring or something?
  21. Apheared

    Drilling cases and PCBs

    eric, I dunno man it's a "multipurpose" and aluminum is soft... as metals go, anyway. This thing will ziiiip thru a 2.5mm faceplate... I could sign my name with it like a pen. If you're talking steel it'll work but it's much slower and heats up real fast (as anything in a dremel does) Hey...
  22. Apheared

    Drilling cases and PCBs

    Right tool, wrong bit... try those spiral cutter bits, or tile cutter bits. I use a #561 And it *IS* like thru butter. You'll get nervous that you'll over-cut, it's so easy.
  23. Apheared

    Distortion in Apheared 47 amp.

    Ok, is it a choppy crackly kind of distortion that's (for lack of a better word) edgy? Or more a smoother warmer "fuzzy" distortion, like what an overdrive for a guitar sounds like? (the former is probably oscillation, the latter is probably a short on the output, although I haven't fully tested...
  24. Apheared

    Transformer and diodes burning up

    yep that's all good, but remember that on one of the bridge setups, the "negative" side is really gonna be the positive... or the least negative, anyway. So the spot between them becomes the virtual ground. Wiring both "low" sides together will probably shoot a spark and dim the lights when...
  25. Apheared

    Transformer and diodes burning up

    Yikes! Yes wire them in phase. It's a good thing. Your transformer datasheet will show the way... Talema's are: http://www.amveco.com/images/2x117v-50-60hz_diagram.gif or for the mini/PC mount: http://www.amveco.com/images/mini_drawings.jpg
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