Re: Malcolm's ruler machine

To: tesla-at-pupman-dot-com
Subject: Re: Malcolm's ruler machine
From: "Robert Jones" <alwynj48-at-earthlink-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sat, 27 May 2000 10:12:15 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
Hi Terry,

More thoughts for extensions.  Add known masses (at least 100 times the mass
of the wire) to the end of the wire and plot the the SQU f against mass.
The intersection with the mass axis is the equivalent of med C.  Then weigh
the wire (moving part only) thats the equivalent of intrinsic C.  Now add
small masses about the same mass as the wire.  You can then check the
addition law.

Regards Bob,


-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Thursday, May 25, 2000 10:55 PM
Subject: Malcolm's ruler machine


>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>Hi All,
>
>I have built sort of a fun toy to study secondary resonance.  Going off
>Malcolm's analogy of a bent ruler model for secondary oscillation, I built
>a simple device.
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/Mach.jpg
>
>It is simply a wooden base with a spring steel wire pressed into a hole.  A
>"woofer" speaker is connected to the base of the wire by a rubber band and
>some small powerful magnets to couple the speaker cone to the base of the
>wire.  The wire is 30.0 inches long and weighs 11.7 grams.  The wires
>natural frequency is 1.81 Hz.
>
>The speaker is driven by a DC-50kHz amplifier from a low frequency
>oscillator with a scope attached to measure frequency:
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/drive.jpg
>
>The first harmonic occurs at 1.81Hz where the wire swings with great
>amplitude.  Decreasing the amplitude did not change the resonant frequency:
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/1st.jpg
>
>The third harmonic occurs at 12.11Hz with far less amplitude.  The nodal
>point is 23.5 inches from the base:
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/3rd.jpg
>
>The fifth harmonic is at 34.13Hz with nodes at 15.25 and 26.0 inches:
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/5th.jpg
>
>The seventh harmonic is at 66.23 Hz with nodes at 10.75, 19.25, 27.0
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/7th.jpg
>
>it is interesting to compare this to actual secondary coil measurements at:
>
>http://users.better-dot-org/tfritz/VoltDistBare.jpg
>
>Is is also interesting to note the similarity of the wire bending profile
>to the graph profile of the measured results:
>
>http://users.better-dot-org/tfritz/site/misc/MalRulMa/Wire.jpg
>
>It is interesting to also note the measured profile is concave rather than
>convex as would be expected in a 1/4 wave sine function as shown in the
>comparison graph here:
>
>http://users.better-dot-org/tfritz/DistGraph.jpg
>
>I don't know what all this means or anything but I wanted to pass this
>information I had on for everyone's enjoyment...  Maybe it will all mean
>something to someone.  I have been so busy getting the thing working that I
>have not thought much about the implications...
>
>For reference, there are many web sites with spring, mass, and oscillation
>information such as:
>
>http://www.futuresouth-dot-com/~mhenders/physics/Simple_Harmonic_Motion.htm
>
>http://www.cs.wright.edu/~fdgarber/199/Spring_Mass_3/
>
>I will try adding weight at the top (like a terminal load) and such in the
>future.  I have to start working on the cap bulk buy first ;-))
>
>Cheers,
>
> Terry
>
>