| MadSci Network: Physics |
transistor is the main element in megaphone. We need to know that
transistor takes a small signal as input, and on the out put it generate
a similar but larger signal. Each transistor has its own
characteristics, and it has minimum and maximum input/output. To amplify
sound transistor will take a small signal (millevolts), and the output
will be in volts or 10’s of volts. Therefore feeding the megaphone with
output of another megaphone means we are feeding the next one with large
signal exceeds its input characteristics. Another fact, from the
characteristics of transistor, we find that the capacity to amplify is
limited to the energy supplied to the transistor; for example, if the
transistor is supplied with 12 volts then its output is limited to this
supply even if its input signal is higher volts there will be no
amplification more than the supplied voltage.
{Moderator's note: The above is for the case of a powered megaphone. In the
case of an unpowered one (basically a cone-shaped tube), the megaphone
concentrates the sound energy over a smaller solid angle, making it louder than
normal there. But it is less loud elsewhere and the total energy is not
increased.)
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