Recent content by TzeYang
  1. TzeYang

    Tiny DAC, Big Sound, Evolved – Stoner Acoustics UD100 / UD110 / UD120

    https://www.facebook.com/StonerAcoustics/photos/a.689220487759500.1073741826.426811050667113/1342274039120805/?type=3&theater
  2. TzeYang

    New Stoner Acoustics Ruby Portable Amplifier

    https://www.facebook.com/StonerAcoustics/posts/1197085356973008 Seems like they are having a sales for the holidays...
  3. TzeYang

    HeadAmp Pico Power: Pre-Order Thread

    Justin, I don't own your products because I'm too poor to afford them, but from an engineer's point of view, I really admire your work. Pure curiosity, how do you deal with the unbalanced 2x 9V batteries causing dc offset issues when they drop low? Does the amp cut off the batteries...
  4. TzeYang

    Post pics of your builds....

    I LOVE what you did to the USB connector.
  5. TzeYang

    Oh how I hate Eagle PCB - Any help with A47 upgrade?

    try diptrace if eagle is too hard to use.  
  6. TzeYang

    DAC Cases and EMI/RFI stuff, Really low level question

    is there noise at the first place?
  7. TzeYang

    2 or 3 Channel, Single Ended Class "A" Design Thread

    just so you know, these ideas are all discussed and done thoroughly before here and on headwize. Eventually, you'll end up with a PRR like MOSFET amplifier with two rails.You could add complexity to the output stage by adding a CFP, add some FETs to the rails, cap multiplier, small shunt regs to...
  8. TzeYang

    2 or 3 Channel, Single Ended Class "A" Design Thread

    if you're going to add an opamp anyway, why not simply build PRR's MOSFET + OPAMP combo with two rails? There's an elegance of using output caps when your circuit is that simple but if you have something that controls the output, having output caps is counter-intuitive.
  9. TzeYang

    General design theory help

    been busy with school. but here's a quickie. Generally, you want to have the input impedance of the non-inverting input and the inverting input to be the same. Hence, R1 || R2 = R3 || R4. This applies greatly to BJT input opamps where there is enough base current to cause dc errors.
  10. TzeYang

    General design theory help

    Quote:   ACTUALLY, the calculation is the same. The input differential stage is self biased. Meaning that input stage current depends on how much voltage you drop across the source resistors and the IDSS curve of the device itself (this varies between devices). The VR1 is there to set...
  11. TzeYang

    General design theory help

    cant be sure, but here goes. correct me if i'm wrong.   input impedance is dominated by R1 and R2. The input impedance of the direct input is usually VERY large, depending on the types of input transistors. In an ideal case, it is assumed to be infinity. You don't really have to look at this...
  12. TzeYang

    Hakko 936 discontinued, viable replacements?

    the only problem you'll probably get is the stupid plastic knob that breaks down after 2 years. Replace with aluminum knob and pretend it's hi-fi.  
  13. TzeYang

    Would 1.5v battery kill a headphone driver testing polarity?

    but are you not heating up the drivers by applying DC across it?
  14. TzeYang

    LM317 dual rail power supply

    With a circuit this symmetric, consider using thicker traces and a star ground.
  15. TzeYang

    PPA v2 construction discussion

    lower the resistor between the buffer and the output of the opamp to about 100 ohms.
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