Date: Fri Aug 28 13:28:46 2009 Back to Contents ------------------------------------------------------------------------

Author: Adolf Cortel

Subject: Re: Sound Bites

Post:

This can be simplified even a bit more! I've just tried a small motor
from an old CD player connected directly to the output of a small radio
and only by biting the rim of the motor the music or news can be clearly
"heard" . In case of more than one user, a piece of paper or plastic can
be wrapped around the rim without loss of the quality of sound. I've
tried a wood rod (15 cm long and 6 mm in diameter) inserted in the axis
and the intensity of the sound increases a bit though the basses are
boosted a lot.
Regards,
Adolf Cortel

IES Pompeu Fabra
Martorell, Barcelona, Spain


Paul Doherty escribió:
> HI Dan
>
> While drilling the hole parallel to the axis is usual for a dowel,
> this still works if the hole is drilled radially for example to avoid
> an eraser.
>
>
> Paul D
>
>
>
>
> On Aug 28, 2009, at 7:30 AM, Daniel Kaplan wrote:
>
>> I have gotten a lot of useful feedback from this question (thanks to
>> all), but the dc motor seems to be the easiest one for me to
>> implement in my setting.
>>
>> Paul - For clarity, I assume that you meant that the hole is axial in
>> the rod? Thanks.
>>
>> Dr. Daniel Kaplan
>> Physics Teacher
>> Matawan Regional High School, Aberdeen, NJ
>>
>>
>> ------------------------------------------------------------------------
>> *From:* tap-l-owner@lists.ncsu.edu
>> on behalf of Paul Doherty
>> *Sent:* Thu 8/27/2009 10:49 AM
>> *To:* tap-l@lists.ncsu.edu
>> *Subject:* Re: [tap-l] Sound Bites
>>
>> Hi Daniel
>>
>> We have this exhibit at the Exploratorium. And Don Rathjen created
>> the Snack for it.
>> Simply drill a small hole in a pencil or dowel and tightly shove the
>> shaft from a cheap DC motor into the hole.
>> Then play music into the DC motor. The shaft will quiver in tune with
>> the music and vibrate the shaft.
>> Slip a straw over the pencil for sanitation and you are good to go.
>>
>>
>> Paul D
>>
>>
>>
>>
>>
>>
>> On Aug 27, 2009, at 2:48 AM, Daniel Kaplan wrote:
>>
>>> I just came back from a vacation in London where I visited their
>>> Science museum. One of the exhibits would be cool to reproduce in
>>> my high school class as a demo that the students could "bite into".
>>> The demo consisted of a thin metal rod that was held horizontally at
>>> one end by some sort of apparatus. The workings of the apparatus
>>> were not visible.
>>>
>>> The user was told to unwrap a clean straw from a stack of available
>>> straws (they had special straws that were shorter than usual - I
>>> could have the student cut down a standard straw) and slide it over
>>> the rod. The next step was to put your fingers in your ears and bite
>>> on the straw. You could then clearly hear some local radio station.
>>>
>>> This is a great demo to show how sound is a transmitted vibration.
>>> To set this up I will need a mechanism to hold the rod quite stiffly
>>> but still be able to transmit vibrations to it. I was thinking I
>>> would try mounting a small speaker on a rod. Maybe if I remove the
>>> cone portion of the speaker I could get vibrations without too much
>>> sound. transmitted through the air.
>>>
>>> Does anyone have suggestions about how to accomplish this? Or has
>>> anyone built a similar demo that they could share some of the details?
>>>
>>> Thanks.
>>>
>>> Dr. Daniel Kaplan
>>> Physics Teacher
>>> Matawan Regional High School, Aberdeen, NJ
>>>
>>
>


From tap-l-owner@lists.ncsu.edu Fri Aug 28 13:28:46 2009

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