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Re: [Phys-l] amplifier



'Better Way": I have an old receiver, two reasonably good Radio Shack speakers, an old portable CD player (an MP3 thing would do) AND a double pole, double throw switch. I can switch to in phase/our of phase on the fly.

"World's Greatest Sound Demo" --2 inch raw speaker, wired to the receiver, play music through the speaker--tinny with no volume. Bring up a 1 foot square (approx) baffle board (can be simple cardboard) with 2 inch hole. Place speaker in hole! Students are astounded! Then talk about mounting raw speakers on back deck in cars!

Rick

***************************
Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN
rtarara@saintmarys.edu
******************************
Free Physics Software
PC & Mac
www.saintmarys.edu/~rtarara/software.html
*******************************
----- Original Message ----- From: "Anthony Lapinski" <Anthony_Lapinski@pds.org>
To: <tap-l@lists.ncsu.edu>; <phys-l@carnot.physics.buffalo.edu>
Sent: Wednesday, April 02, 2008 8:15 AM
Subject: [Phys-l] amplifier


I'm teaching about sound and want to reverse speaker wires (red/black) to
show constructive/destructive interference of sound waves (music) with two
speakers/microphones and an oscilloscope. In the past I used cassette
tapes, an old boom box (volume turned up), and old speakers. I would
reverse the (red/black) wire connection (via alligator clips) for one
speaker while the music played. A bit cumbersome, but it worked.

I now have some songs on the computer (iTunes) and wish to repeat the
demo. However, the old stereo speakers (connected via the earphone jack on
the computer) are not loud enough. The new computer speakers are very
loud, because of the amplifier built in, but I don't want to strip the
wires on them.

So I need an "inexpensive" amplifier to boost the loudness from the
computer (1/8 "earphone jack) to my old speakers. Does anyone know where I
could purchase such an item? I assume Radio Shack might have some stuff.

Any better ways to do this demo?

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