Recent content by mwofsi
  1. mwofsi

    'noodle' dac (ebay special)

    Again, I may be way off base here but I would be inclined to use smaller caps between the regs and after, say 100uF. It's my belief that the size of the caps influences the power supplies ability to respond to changes in demand. I know for sure that it is a complicated subject, power...
  2. mwofsi

    'noodle' dac (ebay special)

    Hopefully error401 or someone will chime in on this, but that looks like a huge amount of capacitance for a 5V supply. I don't know the technical reasons, other than vague memories of bits I've read, but it's not usually the way it's done. One 4700uF and one 1500uF should be more than enough...
  3. mwofsi

    'noodle' dac (ebay special)

    Maybe this is slightly cheaper? High Grade 24bit/192khz DAC with fully assembled kits on eBay, also, CD Players, Home Audio Hi Fi, Consumer Electronics (end time 31-Oct-08 08:00:00 GMT) Prices seem to be going up, the same ebay store seems to have another at a higher price.
  4. mwofsi

    'noodle' dac (ebay special)

    gurusan, the ferrite bead you highlighted has lead me to some further thoughts about this supply I think the bead is possibly there as an attempt to reduce switching noise from the bridge rectifier diodes. Also if there is only one, that suggests that the rectification for the 5V supply...
  5. mwofsi

    'noodle' dac (ebay special)

    Quote: Originally Posted by gurusan Oh, and one other question. In a simple Vreg circuit as used on this noodle DAC psu, what is the function of the polysester caps on either side of the regulator? I have some really questionable looking .0033uF caps on there at the moment but have some...
  6. mwofsi

    'noodle' dac (ebay special)

    Quote: Originally Posted by gurusan If 5V is all I need to power the DAC, then can I just steal it from a USB port? Complicated, it's a poor quality power supply. Best avoided, though Alien dacs and the like do this. EDIT: Your welcome.
  7. mwofsi

    'noodle' dac (ebay special)

    Quote: Originally Posted by gurusan So basically i just need a transformer with only 5V secondaries? Not quite, 5V ac rectified produces 7.1V dc. The ic regulator, the 7805 needs a dc feed of a max of 2.5V above it's output voltage to ensure that it works/regulates. So 6V...
  8. mwofsi

    'noodle' dac (ebay special)

    In that case you obviously have no need for a +/-12V supply, just the regulated 5V, which gets fed to the dac board and is there also regulated to 3.3V. Bit concerned about the melting transformer. A small enough fuse might have stopped it. Possible cause: a faulty transformer, a wiring...
  9. mwofsi

    'noodle' dac (ebay special)

    Quote: Originally Posted by gurusan So would something like this be adequate? Transformer Toroid 0-240 / 2x 0-12 11VA, 8-0-8 3VA on eBay, also Transformers, Components Supplies, Electrical Test Equipment, Business, Office Industrial (end time 02-Nov-08 16:17:55 GMT) Power to...
  10. mwofsi

    Problems With An Ori Modded Zhaolu 2.5A. Anyone Have An Original Schematic?

    Also on the list of to be improved is the ALPS pot for the headamp. Of course ALPS make some really good audio pots, but they make some very ordinary ones too. I suspect that a litttle more care in component choice, (at increased cost to the builder) would make this modded dac the giant...
  11. mwofsi

    Problems With An Ori Modded Zhaolu 2.5A. Anyone Have An Original Schematic?

    Quote: Originally Posted by Asylum years internal headphone amp board It's pretty basic stuff, single mosfet per channel amplification. The whole thing together does sound quite good. More open and clear sounding than my perfectly good pc2707 usb dac, for instance, but there's...
  12. mwofsi

    'noodle' dac (ebay special)

    Quote: better regulation with a higher VA rating I think that for transformers regulation refers to the difference between loaded and unloaded voltages. For an ic regulated supply this shouldn't be a problem as long as the rectified unloaded voltage (x1.42?) doesn't exceed the...
  13. mwofsi

    Problems With An Ori Modded Zhaolu 2.5A. Anyone Have An Original Schematic?

    Erm.... After some desoldering and soldering the problem is found. Turns out that Windows decided to change my default audio device for no apparent reason (patch maybe?). Found by going through the device troubleshooter from the device manager. Nothing ventured, nothing gained. So...
  14. mwofsi

    Non-conductive material as amplifier's casing

    Thankyou for the link gurusan. A good buy. Mike.
  15. mwofsi

    Tool question - Ungar 2110 parts??

    Isn't it just a question of politeness? If you email someone asking for help isn't it more polite to a allow them a few days to a week to answer? A phone call seems more personal and direct, you'd actually get an instant response even if it's just 'I don't know'. Some people prefer it that...
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