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  1. audioguru2

    Help me >>>Circuit Diagram for 12vdc inverted to 220vac generate sinewave

    Maybe you want to make a pure sine-wave inverter that is powered from a 12V battery and produces 220VAC? Inverters are rated in how much power they can produce. You did not say one word about how much power you need from an inverter.
  2. audioguru2

    0-30V Stabilized Power Supply

    I can't find Redwire's schematic. Maybe because it is an Eagle-only file type but i don't use Eagle. I found a few mistakes when compared to my schematic.
  3. audioguru2

    0-30V Stabilized Power Supply

    Hi Effenberg, Why is your schematic a hard to see negative? I changed it to a positive (white background) so i could see it like most other schematics. 1) Some of your opamps have the  pin numbers on the inputs backwards. Some of your opamps have the + and - input symbols backwards. Pin 3 is...
  4. audioguru2

    0-30V Stabilized Power Supply

    Ebay sells cheap broken old junk or cheap Chinese things that fail in one week.
  5. audioguru2

    Brightest LEDs on the planet?

    My compact fluorescent bulbs have 3000k colour temperature and are pure white. 2700k is warm-white (yellowish-orange like incandescent) and 3500k is cool-white (bluish). Very blue ones are called "daylight" but I don't know their colour temperature because I hate them. Corrected colour...
  6. audioguru2

    audio amplifiers

    The LM3886 will try to provide 94W RMS to a 4 ohm speaker when it has a 35V dual-polarity supply which will cause it to over-heat. It is spec'd with a 28V dual-polarity supply which allows 60W into 4 ohms. It is an excellent amplifier.
  7. audioguru2

    Brightest LEDs on the planet?

    It depends on the viewing angle. Cheap Chinese LEDs have a high brightness number because the case focusses the beam into a very narrow angle. Good LEDs are very bright over a wide angle.
  8. audioguru2

    0-30V Stabilized Power Supply

    The latest parts list for the 3A power supply lists a 28V, 4.3A, 118VA transformer.
  9. audioguru2

    0-30V Stabilized Power Supply

    Hi Effenburg, Your transformer is too small for a 5A power supply. It is rated at 30V x 5A= 150VA. But the project makes 42.4V so when the output current is 5A then the transformer will be overloaded with 42.4V x 5A= 212VA. The original project had the same problem with its transformer overloaded.
  10. audioguru2

    audio amplifiers

    A 60W amplifier that drives an 8 ohm speaker might be able to drive a 4 ohm speaker with 60W if its supply voltage is reduced to 0.707 times.
  11. audioguru2

    0-30V Stabilized Power Supply

    For the 3A version of this project, R7 is 0.47 ohms/10W. With 3A in it then it dissipates 4.23W and will be hot enough to melt plastic and maybe char the pcb. The original project used a 5W resistor. It would nearly smoke.
  12. audioguru2

    0-30V Stabilized Power Supply

    A fuse should be installed in series with the on-off switch in the mains wiring to prevent your home from being burned down if something in the project goes wrong. But I think England has a fuse in the electrical plug.
  13. audioguru2

    connect two diff make 24 power supply in parallel.

    If the supplies have regulated output voltages then in parallel they will "fight" each other. The first one might have a voltage slightly higher than the second one. Then the circuit in the second one will reduce its output voltage because it is too high. The circuit in the first one will...
  14. audioguru2

    0-30V Stabilized Power Supply

    If a 28V transformer is rated at 3A then it is made as a 30V transformer because the designer knows that its voltage will drop 2V due to the resistance of its windings. The cheap little 9V/200mA wall-wart is made as a 15V one because ..... (same thing).
  15. audioguru2

    audio amplifiers

    Rod Elliot has many good amplifiers and other audio projects on his site: http://www.sound.westhost.com/projects.htm
  16. audioguru2

    0-30V Stabilized Power Supply

    Because the windings have resistance. The output voltage drops down to the transformer's rating only when it has its rated load. Test the output voltage of a 9V/200mA wall-wart. It is 9V only when it has a 200mA load but is 15V or more without a load due to the resistance of its windings.
  17. audioguru2

    0-30V Stabilized Power Supply

    No. A 28VAC transformer might be 30VAC without a load. Then its peak voltage is the root of two times 30V= 42.4V and the full-wave rectifier charges the main filter capacitor to +41VDC. IC U3 also has a negative -1.3V supply so its total would be 42.4V which is very close to its max allowed...
  18. audioguru2

    0-30V Stabilized Power Supply

    The 28V transformer might be 30V without a load on the project. Then it makes an unregulated positive voltage of 41V plus a negative -1.3V supply for U1. The total of 42.3V is very close to the max total allowed voltage of 44V and heats the IC. So the 10V zener diode reduces the max voltage and...
  19. audioguru2

    0-30V Stabilized Power Supply

    A 12,000uf/63V capacitor is available in North America at Digikey or Newark. You can add smaller capacitors in parallel if you want but then their total cost is more. The capacitance can be higher then the project will work better.
  20. audioguru2

    0-30V Stabilized Power Supply

    When the current is 3A then R7 dissipates 3A squared x 0.47ohms= 4.23W. Q2 dissipates as much as 2.3W when the output is 3A and is shorted. The output transistors dissipate a total of 117W when the output is 3A and is shorted. That is a lot of heat.
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