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  1. Audioguru

    Quick n Dirty answer needed

    The datasheet of an LM555 shows on a graph that its output typically goes low to 0.25V. The forward voltage of a modern very bright green LED is 3.0V to 3.6V and its maximum allowed current is 30mA. Then in that WRONG circuit from a student in India, some LEDs will light properly, most LEDs...
  2. Audioguru

    A Funny Thing Happened on the way to this circuit

    My cheap Chinese flashlight has 24 white LEDs in parallel and it works fine. All the LEDs must have been tested and grouped into groups having only one matching forward voltage. The forward voltage is about 3.2V and if a few 2V red LEDs were additionally in parallel then the red ones would light...
  3. Audioguru

    How to connect piezo speakers to an amplifier

    In Canada, a "siren" sweeps its frequency up and down in a speaker. Its speaker is a tweeter that can also play music. But a smoke or CO alarm produces a single frequency beeeep and is in a tuned enclosure causing it to be VERY loud at its tuned frequency. Usually a piezo beeper has an...
  4. Audioguru

    How to connect piezo speakers to an amplifier

    1) The HiFiBerry amplifier is made to produce 15W into 8 ohms at high distortion when its power supply is 18V. 2) Banggood wrongly says TAS3116 but also says the correct TPA3116 for their amplifier IC. The same amplifier sold by Amazon shows that it must be mechanically assembled and has a...
  5. Audioguru

    How to connect piezo speakers to an amplifier

    Kemo and Le Son do not say the maximum allowed power of the tweeter. V Automotive Line shows 150W when a 15 ohm attenuating resistor feeds 51W to the tweeter, is 51W the maximum allowed power? The TAS5756 chip has its cooling metal tab on its bottom so it cannot have a heatsink in top, it uses...
  6. Audioguru

    How to connect piezo speakers to an amplifier

    The new piezo tweeters have a transformer that is 8 ohms but the HifiBerry amplifier produces 30W when it has additional cooling into 4 ohms per channel when the distortion is high (but you do not care about distortion). The power into 8 ohms will be half (15W RMS per channel) with a 18V supply...
  7. Audioguru

    How to connect piezo speakers to an amplifier

    The spec's tor the Kemo Piezo tweeters have no details: 1) Distance for dB output. 2) Peak-to-peak voltage for dB output. 3) What frequency (probably a frequency that produces the highest loudness). Piezo transducers have their dB loudness rated at a distance of only 10cm. Tweeter loudspeakers...
  8. Audioguru

    How to connect piezo speakers to an amplifier

    Whonoes, was your hearing professionally tested? I have normal-for-my-age high frequency hearing loss but I hear high frequencies fine when they are loud enough. My hearing aids do it. A hearing test done by an Audiologist measures the threshold of hearing at various frequencies. Many old...
  9. Audioguru

    How to connect piezo speakers to an amplifier

  10. Audioguru

    How to connect piezo speakers to an amplifier

    My dog can hear some of those frequencies.
  11. Audioguru

    How to connect piezo speakers to an amplifier

    If the amplifier is an antique and uses vacuum tubes and has an output transformer then the output transformer must have its rated load.
  12. Audioguru

    How to connect piezo speakers to an amplifier

    ANY audio amplifier can drive the piezo speaker since its current is very low. It operates with voltage, up to 30V peak-to-peak which would be from an amplifier rated to produce 14W into 8 ohms. Its rated 15V p-p will be produced by an amplifier rated to produce 3.5W into 8 ohms. The graph...
  13. Audioguru

    Inverter issue

    Your inverter is very sick. Its idle current should be very low without a load because it is not working hard. Yours is heating with 122V x 20A= 2440W. Driving a 2400W load its efficiency should be 80% or better then its heating should be only 800W or less. I do not know if a schematic and...
  14. Audioguru

    Timer 555 voltage

    2 months delivery time? Which planet are you on? Oh. You buy cheap fake parts from China?
  15. Audioguru

    Why is this Happening to Me?

    I design electronic circuits on stripboard because it is quick and it exercises my brain. I cut the strips to length to make the layout compact then the strips, parts and a few short jumper wires complete the circuit.
  16. Audioguru

    Why is this Happening to Me?

    The circuit you found will slowly destroy the transistors if the battery is higher than 8V and the LEDs are red. Because, a capacitor charges to about 9V - 2V for a red LED= 7V. Then when this transistor turns on it causes the base of the other transistor to go near -7V but most little...
  17. Audioguru

    Why is this Happening to Me?

    Some Instructables and You-Tube videos are designed by a kid who is 10 years old and knows nothing about electronics.
  18. Audioguru

    Transistors

    Be careful about the pinouts. The BCxxx transistors have the European CBE pinout but most of the other ones have the American EBC pinout. The 13001 transistor has both the previous pinouts plus the oriental BCE and ECB pinouts.
  19. Audioguru

    Timer 555 voltage

    When I order electronic parts from Digikey or Newark before 8:00PM, they are delivered to me the next morning and I am in a different country from them.
  20. Audioguru

    Timer 555 voltage

    Two 9V batteries will quickly drop the voltage too low for an LM7815 voltage regulator to work. Then the voltage keeps dropping.
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