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  1. audioguru2

    0-30V Stabilized Power Supply

    If C7 (the output capacitor) is an electrolytic type then it has "dielectric absoption" where it stores a charge even if it is shorted. Then the output always has a voltage even if the voltage pot is turned down. It also messes up the setting of RV1 that should adjust the output offset voltage...
  2. audioguru2

    0-30V Stabilized Power Supply

    I don't know which opamp you used for U2 and I don't know which schematic you used. My latest schematic shows the input offset adjustment used for the MC34071 and the TLE2141 opamps:
  3. audioguru2

    Virus warning

    A few minutes ago my anti-virus software updated itself and now I don't have the virus warning anymore. The virus file is quarantined (there are many of the same one now) so they are de-activateed. It was a false alarm, maybe caused by the China incedent with them hacking Google.
  4. audioguru2

    Virus warning

    The virus might be a false hit on many anti-virus softwares. Many people think it originates with Google ads.
  5. audioguru2

    Virus warning

    Each time I log in here or navigate and on two other electronic chat sites I get a virus warning. I can log in and navigate without the warning on many other sites.
  6. audioguru2

    Parametric Interaction

    Yes. Then you will need many custom-made 200kHz ultrasonic transducers, a circuit and an algorithm program.
  7. audioguru2

    Parametric Interaction

    I think he is talking about common wireless headphones that use modulated IR or modulated ultrasonic waves. Here is an IR transmitter and receiver that uses FM modulation: An ultrasonic circuit would be similar.
  8. audioguru2

    Parametric Interaction

    You did not desribe the details of what you are talking about. A few years ago a company developed a very powerful array of ultrasonic transmitters because an array is very directional. They also developed an algorithm that modifies the AM modulation to make it more efficient and to reduce...
  9. audioguru2

    JFET Mic Pre Advise Please

    You have sketched a class-A heater. Usually the bottom transistor is connected as a constant current sink but yours is turned on hard all the time. Use a resistor instead of the bottom darlington. Metal film resistors produce a little less noise than carbon film resistors and also are made in...
  10. audioguru2

    0-30V Stabilized Power Supply

    1) It does not give 3A at 30V. 2) It has many of its parts overloaded and operating at voltages higher than the max allowed voltage for them. 3) It is not accurate and is not reliable.
  11. audioguru2

    JFET Mic Pre Advise Please

    I think Mr Evengravy records electric guitars so he likes the even harmonics distortion caused by Jfets and vacuum tubes. He also likes overdrive but not the severe clipping distortion produced by opamps. He is lucky that the Japanese Jfets are binned into fairly low ranges of conductance.
  12. audioguru2

    New Spam

    There is another SPAMMER selling fake Viagra on the High Voltage forum. Luckily it is not a virus (or maybe it is). When was the last time a real thread was posted on the High voltage forum? A few of years ago? Many topics have been SPAM. So it is time to close the High Voltage forum and let...
  13. audioguru2

    JFET Mic Pre Advise Please

    The voices of most TV announcers and reporters are badly clipped. The sounds on some CDs are badly clipped. But a vacuum tube or Jfet clips "gracefully" and does not sound as harsh as an opamp that is clipping. I have heard many compressors that cause horrible distortion because their attack...
  14. audioguru2

    JFET Mic Pre Advise Please

    My ACDSee viewing program shows why the fuzzy JPG file type is fuzzy and why the simple schematic uses more than half a million bits:
  15. audioguru2

    JFET Mic Pre Advise Please

    Why use Jfets? Why not use an audio opamp instead? Why use an expensive condenser mic that needs a 48V supply? Why not use an inexpensive but high quality electret mic instead that has the 48V built-in on its electret material? An electret mic needs to have its built-in Jfet to be powered. Your...
  16. audioguru2

    Simple FM transmitter question/s + help

    The project is titled, "Simple" which means poor performance. Its antenna is connected directly to its tuned circuit so its frequency changes when something moves toward the antenna which increases the capacitance and when something moves away from the antenna which reduces the capacitance. It...
  17. audioguru2

    how many 10v leds for 230AC and a few other questions.

    We do electronics where we design and build complicated electronic circuits. Electricians install conduit and pull wires into the conduits. Then they connect simple lights and switches. Most electricians do not know anything about electronics.
  18. audioguru2

    0-30V Stabilized Power Supply

    I don't know whose schematic has D15. Mine shows a new 10V/1W zener diode that reduces the supply voltage to U3 but it does not have a part number and is missing on my latest parts list.
  19. audioguru2

    1.5v to 5v

    A alkaline D cell is 1.5V only when it is brand new. When it is supplying 1A or more then its voltage keeps dropping. It can supply 1A for 4 hours when its voltage will have dropped to 1.0V. It can supply 5A for about 20 minutes when its voltage will have dropped to 1.0V.
  20. audioguru2

    0-30V Stabilized Power Supply

    I don't know why you have two 30V windings on your transformer. 30V makes a peak voltage of 42.4V that feeds the bridge rectifier and main filter capacitor. If the load on the project is 5A then its max power is 42.4V x 5A= 212W. Therefore the 30V transformer must be rated at 212VA or 7.07A or...
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