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Principal cause of acoustic feedback Most, if not all, of us have experienced hearing that piercing whistle from sound systems. What causes it and what can we do to minimize or eliminate it? There are several types of feedback but in this case, the proper name is acoustic feedback, the type of feedback that you can hear. In simple terms, feedback happens when the sound from the speakers enters the microphone/s, goes through the mixers and amplifiers, out through the speakers and back into the microphone/s. In the case of guitars, the sound from the speakers make the guitar strings vibrate, which goes through the sound system, out the speakers, and vibrates the strings again. So, essentially, the sound is going 'round and 'round the sound system. Feedback may be caused by microphones, guitar pickups, and other sound system inputs along with speakers. They can range in frequencies from a low rumble to an ear-splitting shriek. So, how can you prevent your sound system from g

email supposedly from Kindle Direct Publishing I received another email with a proposal to convert my book into a movie. This time, it's from Kindle Direct Publishing. It's obviously fake because the sending address is amazon_submissions_at_gmail_com. Amazon using a gmail address? Furthermore, my book is hardly a bestseller. If it was a bestseller, I'd understand if someone would contact me with a proposal such as this but it's nowhere near being even moderate seller. Lastly, if some big movie production outfit really wanted to convert my book to a movie, I don't think they will ask me to submit a screenplay. Of course, they would offer to make the screenplay for me, which means I will have to pay for it. I would think a real proposal would be free. If you're also a budding author and received something like this, don't believe it right away. Look at the sending address. If it's a gmail, yahoo, or other free, public email service, don't believe it.

  Pinout diagram of Zilog Z80 microprocessor Back around 1989, I received a request to fix an infusion pump, a device that allows medical staff to pump very small, and precise, amounts of fluids and medicines into patients. I was told it would turn on but wouldn't start pumping. The display showed rubbish and pushing buttons didn't produce any response. I opened the thing and quickly discovered a Z80 microprocessor, a computer chip that I had been studying for some time with the intention of building my own computer. I was very familiar with it. From the description of the problem, it seemed as if the unit was not starting up properly. Opening the unit and checking pin 26 (the RESET pin), I found...nothing, the pin was floating (unconnected to anything). The chip needs the RESET pin to be held at 0 volts for about a split-second after power-on to start the program at the beginning. If the chip is not reset, the program may start at a random line and the unit will likely