PASCO SE-8657 MOTOR ACCESSORY - Manual (Page 7)

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012-06247A Motor Accessory
¨
source. This is impractical at frequencies
much above 30 Hz, and some students may
require assistance even a lower frequencies.
Maintenance and Storage
- A small box is provided for storing the parts of
the motor not installed on either the Variable
Gap Magnet or Coils and Cores Set.
- The commutators and brushes will experience
wear, oxidation, and pitting and will require at-
tention from time to time. Rotate the armature
slowly by hand and monitor current flow or
sense the force developed to determine whether
proper contact is occurring between brushes and
commutator. To restore proper operation, clean
the contacts with emery paper or shift the
brushes somewhat to expose new surfaces.
- Careless installation of the armature onto the
shaft might bend the brushes. You can easily
bend them back into their original shape with
finger pressure.
➤
NOTE: If you are using a PASCO CI-
6502A Power Amplifier (for the CI-6500
Interface System), the distorted waveform light
will turn on during operation of the motor, but
no damage is being done to the Power Ampli-
fier; you can ignore the light.
Starting the motor
- The motor is not self-starting. Immediately after
you apply the power, start the motor manually by
grasping the black plastic bushing at the top of
the armature assembly between your thumb and
forefinger and spinning the armature.
- With the Motor Accessory configured as either a
DC or universal motor, almost any attempt you
make at spinning the armature will result in suc-
cessfully starting the motor; only the direction of
the spin is important.
- When configured in an AC synchronous mode,
the motor must be spun at a speed that approxi-
mately matches the frequency of the power
Operation
Options for electrical connections
- Banana-style plugs may be inserted into openings
in the ends of the black plastic brush holder.
- Large alligator clips may be attached to the brass
posts that hold the brushes.
- Small alligator clips may be attached directly to
the ends of the brushes where they protrude from
the slits in the brass posts.
Options for Power Sources
It is important to limit the current of the power source
to 1.0 A to avoid damaging the coils of the armature.
Either choose a power supply that can be set to deliver
a maximum current of 1.0 A, or use your power
source connected in series with a multimeter or
ammeter to monitor the output current. (Alterna-
tively, to avoid possible damage to a sensitive
ammeter, you can measure the voltage drop across
a low-value series resistor, such as a 0.51 ohm, 1
watt resistor, and calculate the output current.) You
will also need to adjust and measure the output
voltage, so if your power supply does not have this
capability, you will need a multimeter or voltmeter.
(See Table 1 for specific suggestions for power
sources.)