PASCO ME-8750 User Manual

Instruction Sheet
for the PASCO
Model ME-8750

HARMONIC OSCILLATOR/DRIVER

012-05931A

1/96

$1.00

Introduction

Offset

Driving Arm

String holder

String

The PASCO ME-8750 Harmonic Oscillator/Driver is de­signed to drive apparatus requiring a low frequency (0.3
to 3 Hz), high torque, sinusoidal oscillation. It consists of
a DC motor with an offset driving arm and a mounting
bracket. A string can be attached between the driving
arm and the apparatus which is to be driven. The Oscilla­tor/Driver will provide a sinusoidal pull on the string. If
one desires to both push and pull on an apparatus, the
PASCO Push/Pull Accessory (ME-8751) may be added
to the Oscillator/Driver.

DC Motor

Mounting Bracket

String Guide

Equipment

Features

Operation of the Oscillator/Driver

➀ Mounting: The Oscillator/Driver can be mounted to a

dynamics track to drive dynamics carts or it can be
mounted on a rod stand for driving other apparatus.
See Figures 1 and 2. Tie one end of a string to the
white plastic piece on the driving arm and thread the
other end of the string through the hole in the guide.
The level of the guide can be adjusted by about 5.5 cm
to match the height of the object to be driven.

Harmonic

Oscillator/Driver

Power Source

Connectors

Photogate

Figure 1: Oscillator/Driver Mounted on a Rod Stand

Harmonic

Oscillator/Driver

Rod Stand

Power Source

Connectors

• 12 VDC motor (frequency: 0.3-3 Hz, current: 0-

0.3 A)

• Adjustable Amplitude: adjustable up to 12 cm.

• Photogate Attachment: A photogate can be at­tached to measure the frequency of the oscillator.

• Driver mounts on Dynamics Track or Rod Stand

• Rubber washers on mounting bracket provide qui­eter operation on the dynamics track.

• Optional Push/Pull Accessory (ME-8751):
Mounts to oscillator, replacing the string and al­lowing the apparatus to be pushed as well as
pulled.

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Dynamics

Track

Figure 2: Oscillator/Driver Mounted on Dynamics Track

© 1996 PASCO scientific
This instruction sheet written/edited by: Ann & Jon Hanks

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Harmonic Oscillator/Driver 012-05931A

➁ Amplitude Adjustment: To vary the amplitude,

loosen the thumb screw that holds the arm to the mo­tor shaft and slide the arm to a new position. Re­tighten the thumb screw to hold the arm in place. The
amplitude is zero when the arm is positioned such that
the screw which holds the string holder is aligned over
the motor shaft.

➂ Power Supply: Plug the leads from the Oscillator/

Driver into a 12 V (0-0.3 A) variable DC power supply.

➤ NOTE: Do not exceed 12 V.

➃ Frequency Adjustment: To adjust the frequency,

change the voltage of the power supply. An increase
in the voltage corresponds to an increase in the fre­quency.

➄ Measuring the Frequency: Mount a photogate onto

the Oscillator/Driver using the slot located below the
motor. Each period, the arm will block the photogate.
See Figure 1.

Harmonic

Oscillator/Driver

Suggested Uses for the Oscillator/Driver

➀ Attach a spring to each end of a dynamics cart. Con-

nect the free end of one spring to the adjustable end
stop at one end of the dynamics track. Connect the
free end of the second spring to a string tied to the
Oscillator/Driver and threaded through the string
guide. Drive the spring and cart system at various fre­quencies to find the resonant frequency of the system.

➤ NOTE: It generally takes the system a little
time to respond to a change in frequency of the
driving force so some patience is needed to see the
resulting change in amplitude.

➁ Use two carts and three springs to find the resonant

frequencies of the two different modes of oscillation.
See Figure 3.

Other Suggested Uses Requiring Additional
Push/Pull Accessory

➂ Mount the Oscillator/Driver on a rod stand and hang a

Longitudinal Wave Spring (WA-9401) from the hook
on the Push/Pull accessory. Create a transverse wave
in the spring to demonstrate that the wavelength varies
down the length of the hanging spring.

➃ Drive a set of hanging balls (see Figure 4) at various

frequencies to show different modes of oscillation and
chaotic motion.

Springs

Dynamics Carts

Dynamics Track

Figure 3: Resonant Modes of Oscillation of Carts and Springs

2

Adjustable

End Stop

®