Center 321 User manual
CONTENTS
Title Page
I. SAFETY INFORMATION………..………..…………..1
Environment conditions………………………………..1
Maintenance & Clearing……………………………….1
Safety symbols………………………………………… 1
II. GENERAL DESCRIPTION……………………..……..2
III. SPECIFICATIONS..…………………..………………..3
IV. NAME AND FUNCTIONS..………….………………..5
V. AUTO POWER OFF……….………………….……… 6
VI. CALIBRATION PROCEDURES….………………….. 7
VII . MEASUREMENT PREPARATION………….……….7
VIII. OPERATING PRECAUTIONS………………………. 8
IX. MEASUREMENT………….………………………..…8
SOUND LEVEL METER
1
I. SAFETY INFORMATION
Read the following safety information carefully before attempting to operate or
service the meter.
Use the meter only as specified in this manual; otherwise, the protection
provided by the meter may be impaired.
Environment conditions
Altitude up to 2000 meters
Relatively humidity 90% max.
Operation Ambient 0 ~ 40℃
Maintenance & Clearing
Repairs or servicing not covered in this manual should only be performed by
qualified personnel.
Periodically wipe the case with a dry cloth. Do not use abrasives or solvents
on this instruments.
Safety symbols
Comply with EMC
When servicing, use only specified replacement parts.
II. GENERAL DESCRIPTION
Thank you for using our Sound Level Meter. To ensure that you can get the
most from it, we recommend that you read and follow the manual carefully
before use.
This unit conforms to the IEC651 type2, ANSI S1.4 Type2 for Sound Level
Meters.
It uses RS232 interface to perform bi-directional communication with PC.
SOUND LEVEL METER
2
III. SPECIFICATIONS
Standard applied : IEC651 Type2, ANSI S1.4 Type2.
Frequency range : 31.5Hz ~ 8KHz
Measuring level range : 30 ~ 130dB
Frequency weighting : A / C
Microphone : 1/2 inch electret condenser microphone
Display : LCD
Digital display : 4 digits
Resolution: 0.1dB
Display Update: 0.5 sec.
Analog display : 50 segment bargraph
Resolution : 1dB
Display Update : 100 mS
Time weighting : FAST ( 125mS ), SLOW ( 1 sec. )
Level ranges : Lo : 30 – 80 dB
Med : 50 – 100 dB
Hi : 80 – 130 dB
Auto : 30 – 130 dB
Accuracy : ±1.5dB ( under reference conditions @ 94dB, 1KHz )
Dynamic range : 50 dB
Alarm function : “OVER” is when input is more than upper limit of range.
“ UNDER ” is when input is Less than lower limit of range.
MAX/MIN hold : Hold readings the Maximum and Minimum Value.
AC output : 1 Vrms at FS ( full scale ).
Output impedance : Approx. 100Ω
FS: means the upper limit of each level range.
DC output : 10mV / dB , output impedance approx. 1KΩ
Power supply : One 9V battery, 006P or IEC 6F22 or NEDA 1604.
Power life : About 50hrs ( alkaline battery )
AC adapter : Voltage 9 VDC ( 8-15VDC Max )
Supply current : > 30mADC Socket : pin →Ground
Casing →Positive ExternalDiameter →3.5mm
Internal Diameter →1.35mm
SOUND LEVEL METER
3
Electromagnetic Compatibility:
RF field = 3V/m
Total accuracy = specified accuracy + 0.5dB
Operation temperature : 0 to 40℃( 32 to 104℉)
Operation humidity : 10 to 90%RH
Storage temperature : -10 to 60℃( 14 to 140℉)
Storage humidity : 10 to 75%RH
Dimensions : 275 (L) ×64 (W) ×30 (H)mm
10.8 (L) ×2.5 (W) ×1.2 (H)inch
Weight : 285g ( including battery )
Accessories : 9V battery, carrying case, Screwdriver, Instruction manual.
Windscreen, 3.5ψplug.
Optional : Software, RS-232 cable.
IV. NAME AND FUNCTIONS
OPEN
MANUAL FOR SAFETY
NEDA 1604 6F22 006P
PLEASE READ
9V BATTERY
IEC 651 TYPE II
80dB
100dB
130dB
Lo = 30
Med= 50
Hi = 80
LEVEL
FASTMAX
A/C
2
1
3
4
5
7
6
8
9
DC 9V CAL
OUTPUT -
RS 232
SOUND LEVEL METER
4
○
1Windscreen
If you operate at wind speed over 10m/sec, please put protective
accessories in front of the microphone.
○
2Display
SYMBOL FUNCTION
LCD 4digits
MAX Maximumindication
MIN Minimumindication
Over range
Under range
FAST Fast response
SLOW Slow response
dBA A-Weighting
dBC C-Weighting
Range Indicate
Low-Battery
Under range 20dB
AUTO Auto Level range selective
○
3Power & Backlight button
The ○
Ikey turns the sound level meter ON or OFF and backlight ON &
OFF.
Press it once to turn on the sound level meter.
Press it again for moment to turn ON or OFF backlight .
Press and hold this button 3 second to turn OFF the power.
SOUND LEVEL METER
5
○
4MAX / MIN hold button
Press button to enter the maximum and minimum recording mode.
Select the proper Level range before using MAX/MIN to ensure that reading
value will not exceed the measurement range. Press once to select MAX
value. Press again to select MIN value, and press again to select current
value with “ MAX MIN “ annunciator blinking.
Press and hold down button for 2 seconds to exit the MAX MIN mode.
Note: If change sound level range or change A-C weight, the MAX.MIN
mode will clear.
○
5Level range control switch
Each time the UP button Vis pressed. The level range increments from
“ Lo ” Level to “ Hi “ Level range and to “Auto” Level range.
Each time the DOWN button Wis pressed. The range decreases from
“Auto” Level range to “ Hi ” Level and to “ Lo “ Level range.
○
6Frequency Weighting select button
A : A - Weighting. for general sound level measurements.
C : C - Weighting. for checking the low-frequency content of noise.
( If the C-Weighted level is much higher than the A-weighted level, then
there is a large amount of low-frequency noise )
○
7Time weighting select button
FAST : for normal measurements
SLOW : for checking average level of fluctuating noise.
○
8Microphone
1/2 inch Electret Condenser microphone
○
9CAL potentiometer
Calibration control , For level calibration adjustment.
○
10 RS-232 Interface:
The RS-232 signal output is a 9600 bps N 8 1 serial interface.
SOUND LEVEL METER
6
DC Signal
AC Signal Ground
○
11 Signal output terminal
AC: 1 Vrms Corresponding to each range step.
Output impedance ≒100Ω
Output signal by standard 3.5mm coaxial socket signal on pin.
Note: At “Auto” level range, output signal is Auto select on “Lo” or “Med”
or “Hi” level range.
DC: Output : 10mV/dB
Output impedance ≒1KΩ
Output signal by standard 3.5mm coaxial socket signal on middle.
○
12 External DC 9V power supply terminal
For connection with AC adapter.
○
13 Tripod mounting screw.
○
14 Battery Cover
V. AUTO POWER OFF
By default, when the meter is powered on, it is under auto power off mode.
The meter will power itself off after 30 minutes if no key operation and no
RS232 communication and no recording combination at power on can
disable auto power off.
One may press and hold “FAST/SLOW” button and then power on the meter
and the will not show up to indicate that auto power off is disabled.
SOUND LEVEL METER
7
OUTPUT
DC 9V CAL
RS-232
IEC 651 TYPE II
POWER-UP OPTIONS
MIN
MAX SLOW
FAST
LEVEL
Auto=
Hi =
Med=
Lo = 50
30
80
30 100 dB
130 dB
130 dB
80 dB
AC
VI. CALIBRATION PROCEDURES
Using a standard Acoustic Calibrator
( 94dB , 1KHz Sine wave )
(1) Make the following switch settings.
Display : dBA
Time weighting : FAST
Measurement mode : MAX MIN Mode function disable.
Level range : 50 to 100dB
(2) Insert the microphone housing carefully into the insertion hole of the
calibrator.
(3) Turn on the switch of calibrator and adjust the CAL potentiometer of the
unit . The level display will indicate the desired level .
All products are well calibrated before shipment.
Recommended Recalibration cycle : 1 year.
VII . MEASUREMENT PREPARATION
(1) Battery Loading
Remove the battery cover on the back and put in one 9V Battery.
(2) Battery Replacement
When the battery voltage drops below the operating voltage, this symbol
will appear . Replace 9 Volt battery.
Acoustic Calibrator
Screwdriver
SOUND LEVEL METER
8
(3) AC Adapter Connection
When the AC adapter is used , insert the plugs of the adapter into the
DC9V connector on the side panel.
VIII. OPERATING PRECAUTIONS
(1) Wind blowing across the microphone would bring additional
extraneous noise.
When using the instrument in the presence of wind , it is a must to mount
the windscreen to not pick up undesirable signals.
(2) Calibrate the instrument before operation if the instrument was not in use
for a long time or operated in bad environment.
(3) Do not store or operate the instrument at high temperature and high
humidity environment.
(4) Keep microphone dry and avoid severe vibration.
(5) Please take out the battery and keep the instrument in low humidity
environment. When not in use.
IX. MEASUREMENT
(1) Open battery cover and install a 9V battery in the battery compartment.
(2) Turn power on and select the desired response Time and Weighting. If the
sound source consists of short bursts or only catching sound peak, set
response to FAST. To measure average sound level, use the SLOW setting.
Select A-weighting for general noise sound level and C-weighting for
measuring sound level of acoustic material.
(3) Select desired Level.
(4) Hold the instrument comfortably in hand or fix on tripod and point the
microphone at the suspected noise source , the sound pressure level will
be displayed.
(5) When MAX MIN ( maximum, minimum hold ) mode is chosen. The
instrument captures and holds the maximum and minimum noise level for a
long period using any of the time weightings and ranges.
Press the MAX MIN button 2 seconds to clear the MAX/MIN reading .
“ MAX/MIN ” symbol disappears.
(6) Turn OFF the instrument and remove battery when not in use.
4 / F NO. 415, Jung-Jeng Rd., 238 Shu-Lin, Taipei, Taiwan
FAX: 886-2-26763925 http : / / www.centertek.com 321-00
CENTER TECHNOLOGY CORP.
Distributor in Australia
Pacific Sensor Technologies Pty Ltd
Unit 4, 3 Neutron Place Rowville, VIC 3178 Australia
1300 662 720 | [email protected]
www.pacificsensortech.com.au
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