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  1. audioguru2

    stereo Transmitter

    Harry's 222 stereo coder is very crude like he says. It does not have enough pre-emphasis and has no filtering whatsoever. Without filtering, harmonics of audio will heterodyne with the 19kHz pilot and with the lower 38kHz sideband frequencies and create whistles in the sound. His choice of an...
  2. audioguru2

    Veronica PLL

    There are a few Veronica 1W FM transmitter circuits. The 1st one you posted is the PLL version and might have a little amount of pre-emphasis. The last one you posted has none, and the articles say to use their "professional limiter compressor" or their "stereo coder" circuit that has...
  3. audioguru2

    200W kemokit-need help

    The booster transistors are supposed to turn on when the voltage across the 2.2 ohm resistors is about 0.7V. Therefore the power in the resistors is only 222mW half the time when the amp is working fairly hard. Maybe your power supply voltage is too high for the TDA2030 ICs. Their absolute max...
  4. audioguru2

    Darlington TR

    You reduced the value of your bypass capacitor (for the emitter resistor?). Therefore you introduced negative feedback only at low frequencies. Your harmonics pic shows that distortion for higher frequencies remains the same as with a much larger bypass capacitor. An unbypassed emitter resistor...
  5. audioguru2

    Stepper motor H bridge

    The H bridge IC will burn out very quickly if the motor draws more current than the IC's current rating.
  6. audioguru2

    Frequency to voltage conversion

    Good, it works. ;D
  7. audioguru2

    Veronica PLL

    If the Veronica transmitter has enough gain. If the Veronica is not stereo, because the boosted high audio frequencies need to have sharp lowpass filters to avoid having the 19kHz pilot signal and the 38kHz stereo sidebands from being messed-up.
  8. audioguru2

    stereo Transmitter

    An FM transmitter needs a mono audio signal or a composite stereo signal for an input. A mono audio signal can be from a microphone and most FM transmitter circuits have enough gain for a microphone. Stereo inputs to the stereo encoder can be from a CD player or an MP3 player. The stereo...
  9. audioguru2

    Darlington TR

    Look at crossover distortion in Google. Your single transistor cannot produce crossover distortion. Crossover distortion is caused by two transistors as emitter-followers in the output of a power amplifier and without enough bias current so they operate in class-B. The distortion occurs when the...
  10. audioguru2

    Veronica PLL

    FM radios have de-emphasis which is treble cut. Since the Veronica transmitter doesn't have pre-emphasis to match it then it will sound something like an AM radio or like your stereo with its treble control turned all the way down. Not good.
  11. audioguru2

    Darlington TR

    Your input and ouput levels are very low. Turn them up and you will see gross distortion because your trsnsitor doesn't have any negative feedback:
  12. audioguru2

    stereo Transmitter

    The stereo coder uses a lot of parts, doesn't it?
  13. audioguru2

    Bigginers Handbook

    Mixos has fixed the uploads problem here.
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    Good, you fixed it. ;D Be very carefull if Q2 is a 2N2219. If the project is set to a low output voltage and a high current then Q2 will melt.
  15. audioguru2

    Veronica PLL

    Silicon Chip magazine has an FM stereo transmitter project called Micromitter that uses Rohm's modern IC that has a very accurate PLL. The IC is inexpensive and is available at many suppliers. The project operates very well and is much smaller than an old Veronica.
  16. audioguru2

    Frequency to voltage conversion

    0.1uF capacitors are very common. They are metalized plastic film, not electrolytic. They are called "green caps" or "mylar". Frequently they are marked 100nF or 104. A 0.47uF capacitor at the input will work fine. I think the attachments are fixed now on this site.
  17. audioguru2

    stereo Transmitter

    I am also confused about Rohm's new FM stereo transmitter ICs because their datasheets don't have any details. They all appear to use a 7.6MHz crystal with a PLL as a very accurate RF frequency synthesizer and the crystal's frequency is divided for very accurate stereo frequencies. The stereo...
  18. audioguru2

    Upload Folder is Full

    Something is wrong. Complain to admin.
  19. audioguru2

    NiMH Battery Pack Charger

    Yes. If the vol;tage doesn't rise to the volts that are expected then the battery must have a shorted cell. It shouldn't take much time but you need to experiment to find out exactly how long. Maybe a charger IC has the amount of time. I think the charger circuit will miss detecting the full...
  20. audioguru2

    Upload Folder is Full

    Some people post the same thing on many electronics chat sites. It is funny to see how the answers are different and to see how the threads go in different directions.
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