2
markings.
Between these two markings, a Hall
sensor is built into the bearing rod. It is aligned in
such a way that field lines run in the direction of
the chip when the pendulum is at rest, meaning
that there is then no Hall effect detectable. An
electronic module for sensing angle is screwed
onto the bearing rod. This transducer detects the
angle of deflection of the pendulum and converts
it into an electric signal which is proportional to
that angle. If the pendulum is deflected from the
vertical by an angle
, a horizontal field compo-
nent arises, which results in a positive or negative
output voltage depending on the direction.
A disc-shaped weight serves as the pendulum
bob.
Power is provided via a 12-V AC plug-in supply
which is included with the apparatus.
Rod pendulum
1000762 is designed for a mains
voltage of 115 V (±10%), while 1000763 is de-
signed for 230 V (±10%).
Note:
The angle sensor is matched to the pair of
magnets of the needle bearing such that the out-
put voltage from the BNC socket is approximately
zero in the rest position. Fine adjustment can be
carried out using the offset adjustment knob. The
arrangement of the needle bearing and the angle
sensor is indicated by a number on the housings.
If equipment with differing numbers is used, it may
be that high offset voltages occur due to the scat-
tering that results from the specific properties of
the magnets.
3. Contents
1
Pendulum rod with U-shaped bracket and nee-
dle bearings
1 Pendulum bob
1 Bearing rod with V-shaped groove and angle
sensor attached
1 Plug-in power supply, 12 V AC
4. Technical data
Operating voltage:
12 V AC
Output voltage:
±5 V
Output resistance:
500 ohms
Maximum length of pendulum: 1 m
Mass of pendulum bob:
1 kg
Weight of angle sensor:
0.3 kg approx.
Bearing rod:
10 mm diam.
5. Operation
The following additional equipment is required to
set up the rod pendulum in order to carry out ex-
periments:
For set-up:
1 Bench clamp
1002832
1 Stand rod, 1000 mm
1002936
1 Universal clamp
1002830
For measurement:
1 Computer
1 PC Oscilloscope 2x25 MHz
1020857
1 HF patch cord
1002746
or
1 Voltage Sensor 10 V
1021682
1 Adapter, BNC Plug/4 mm Jacks
1002750
1 Data logger
1 Software
More information about digital measurement can
be found on the product's webpage in the 3B
Webshop.
5.1 Set-up for rod pendulum
To set up the rod pendulum, attach the stand
rod to the bench in an upright position by
means of the bench clamp.
Attach the bearing rod to the stand rod at a
suitable height by means of the universal
clamp.
Insert the needle bearings for the pendulum
into their intended positions (marked by cir-
cles).
If the bearing rod is not horizontal, then level
it with the help of the adjusting screws.
Move the pendulum bob along the rod to set
up the effective length of the pendulum
L
and
secure the bob with the knurled screw.
Plug in the power supply to connect the angle
sensor to the mains and connect it to the os-
cilloscope via the BNC socket and the patch
cord or to the data logger by means of the
adapter and the voltage sensor.
5.2 Setting offset
Turn on the oscilloscope or the data logger.
If a value other than zero is read when the
pendulum is in its rest position, you can use
the offset adjustment knob to compensate.
