HARMONIC MOTION ACCESSORIES
FOR BOTH THE BASIC AND TWO METER AIR TRACK

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TEL 234 Precision Sine Drive

PRECISION SINE DRIVE

A harmonic oscillator with distinct resonances can be shown with gliders and springs on an air track. For example, for a string of gliders there are as many resonances as there are gliders on the track. As one adds gliders great stability requirements are placed on the sine drive which is used to drive the gliders. The Precision Sine Drive uses a stepping motor which is locked to the drive oscillator. The frequency of the motor drive can be determined with a frequency meter. Resonance frequencies can be easily reset by adjusting the drive to the monitored output shown on the frequency meter. This is necessary for any lecture demonstration of a multi-body resonance. Crystal model analogs with 9 or 10 gliders in a string illustrate phonon and photon transmission through the crystal as well as the "ultraviolet cutoff". Viscous damping, which broadens the resonance peaks and causes the motion to decay after the Drive has been turned off, can be shown by attaching ceramic magnets to the skirt of the glider.

GLIDERS AND SPRINGS ON AIR TRACK FOR STUDY OF RESONANCE

The Precision Sine Drive, which fits on the air track, consists of an oscillator and stepping motor drive circuit and a 48-pole motor which drives a cam and follower. The drive rod attaches to a spring which connects to the first glider in the system. The stroke of the drive rod can be adjusted from 0-2cm. The driver unit sits on the air track surface and is held in place with Velcro^® so that it can be easily moved to any location on the track.

The stepping motor is driven by an adjustable, stable oscillator with a power amplifier providing the pulse-forming phase-shifting network needed for the motor.

AMPLITUDE & FREQUENCY FOR TWO GLIDER STRING

Specifications
Drive Motor — A 48 pole stepping motor directly driving a cam motor maintains exact phase-lock with the driving oscillator.
Sinusoidal — Motion produced by a circular cam mounted eccentrically. Stroke can be adjusted from 0-2cm.
Oscillator-Driver — An adjustable, stable oscillator with the four phase output needed for the stepping motor.
Frequency Range — .2-2 Hz. This range covers all resonances up to 10 coupled 150g gliders.
Interconnection — Motor connects to the rear panel by a 0.5 m long cable and a 6 pin plug.
Controls — Coarse and fine frequency knobs on the front panel and an on/off switch.
Dimensions — Oscillator; 9.5h x 17w x 14d cm
Weight — Both units 2 kg net.

TEL 234

$437.00

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COUPLED HARMONIC OSCILLATORS

TEL 235 Coupled Harmonic Oscillators
A set of five 150 gm gliders, six stainless steel springs, and five ceramic magnets which, when set up in an air track provide a comprehensive course in vibration theory. From the basic configuration of a single glider and 2 springs to 5 gliders and 6 springs the student can set up and find as many resonances as there are gliders. The effect of damping on the sharpness of the resonance curve and the system Q can be determined by using the ceramic magnets. The motion of the magnets produces eddy currents in the metal of the air track causing a damping force proportional tothe velocity and number of magnets on the glider. This corresponds quite nicely to the damping term usually found in theoretical derivations of damped oscillatory motion.

TEL 235

$194.00