Center 320 User manual

Center Technology Corporation
320
SOUND LEVEL METER

Title Page
I. Safety Information……..………………1
II. General Description……..…………….2
III. Specifications…..……………………….2
IV. Name And Functions…..………….….5
V. Calibration Procedures….……………9
VI .Measurement Preparatio.n………..10
VII. Operating Precautions…….………..11
VIII. Measurement…..………………….…..12

1
SOUND LEVEL METER
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
Meter is protected throughout by double insulation or
reinforced insulation.
When servicing, use only specified replacement parts.
Comply with EMC

2
SOUND LEVEL METER
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.
This Sound Level Meter has been designed to meet the
measurement requirements of safety Engineers, Health, Industrial
safety offices and sound quality control in various environments.
RRanges from 30dB to 130dB at frequencies between 31.5Hz
and 8 KHz.
RDisplay with 0.1dB steps on a 4-digits LCD.
RWith two equivalent weighted sound pressure levels, A and C.
RBoth AC and DC signals output is available from Both standard
3.5mm coaxial socket suitable for a frequency analyzer, level
recorder, FFT analyzer, graphic recorder ; etc.
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

3
SOUND LEVEL METER
Display : LCD
Digital display : 4 digits
Resolution:0.1dB
Display Updata: 0.5 sec.
Time weighting : FAST ( 125mS ), SLOW ( 1 sec. )
Level ranges : Lo: 30 - 80 dB
Med: 50 - 100 dB
Hi: 80 – 130 dB
Accuracy :±1.5dB ( under reference conditions )
Dynamic range : 50 dB
Alarm function : “ OVER ” is show when input is more than
upper limit of range.
“ UNDER ” is show 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. 50Ω
FS: means the upper limit of each level
range.
DCoutput : 10mV / dB , output impedance approx. 100Ω
Power supply : One 9V battery, 006P or IEC 6F22 or NEDA
1604.
Power life : About 50hrs ( alkaline Battery )

4
SOUND LEVEL METER
AC adapter : Voltage 9 VDC ( 8-15VDC Max )
Supply current: > 30mADC
Socket:pin →Ground
Casing →Positive
ExternalDiameter →3.5mm
InternalDiameter →1.35mm
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 : 275g ( including battery )
Accessories : 9V battery, carrying case. Screwdriver,
Instruction manual.Windscreen, 3.5ψ
plug.

5
SOUND LEVEL METER
IV. Name And Functions

6
SOUND LEVEL METER
{Windscreen
If you operate at wind speed over 10m/sec, please put
protective accessories in front of the microphone.
|Display
SYMBOL FUNCTION
LCD 4 digits
MAX Maximum Value hold
MIN MinimumValuehold
Over range
Under range
FAST Fast response
SLOW Slow response
dBA A-Weighting
dBC C-Weighting
Range Indicate
Low-Battery
Under range 20dB
}Power Switch
the
Ikey turns the sound level meter ON or OFF.

7
SOUND LEVEL METER
~MAX / MIN hold switch
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.
Sampling rate: 160ms
Level range control switch
Each time the UP switch Vis pressed. The level range
increments from “ Lo ” Level to “ Hi “ Level range.
Each time the DOWN switch Wis pressed. The range
decreases from “ Hi ” Level to “ Lo “ Level range.
Frequency Weighting select switch
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 )
 Time weighting select Switch.
FAST : for normal measurements

8
SLOW : for checking average level of fluctuating noise.
SOUND LEVEL METER
 Microphone
1/2 inch Electret Condenser microphone
CAL potentiometer
Calibration control , For level calibration adjustment.
AC output terminal
1 Vrms Corresponding to each range step.
Output impedance ≒50Ω
Output signal by standard 3.5mm coaxial socket signal on pin.
11 DC output terminal
Output : 10mV/dB
Output impedance ≒100Ω
Output signal by standard 3.5mm coaxial socket signal on pin.
12 External DC 9V power supply terminal
For connection with AC adapter.
13 Tripod mounting screw.
Signal
Ground

9
14 Battery Cover
SOUND LEVEL METER
V.
Calibration Procedures
Using a standard Acoustic Calibrator (94dB , 1KHz Sine wave )
Acoustic Calibrator
Screwdriver

10
SOUND LEVEL METER
(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 .
Our products are all well calibrated before shipment.
Recommended Recalibration cycle : 1 year.
VI . 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,
mark appears . If it appears, battery should be replaced
with new one.
(3) AC Adapter Connection
When the AC adapter is used , insert the plugs of the adapter
into the DC9V connector on the side panel.

11
SOUND LEVEL METER
VII. Operating Precautions
(1) Wind blowing across the microphone would bring additional
extraneous noise.
Once using the instrument in the presence of wind , it is a
must to mount the windscreen to not pick up undesirable
signals.
(2) To achieve more accurate measurement, use an extension
cable to separate the Microphone from the main body so that
the effect of unexpected sound reflection can be eliminated.
(3) Calibrate the instrument before operation if the instrument
was not in use for a long time or operated at bad
environment.
(4) Do not store or operate the instrument at high temperature
and high humidity environment.
(5) Keep microphone dry and avoid severe vibration.
(6) Please take out the battery and keep the instrument in low
humidity environment. When not in use.

12
SOUND LEVEL METER
VIII. Measurement
(1) Open battery cover and install a 9-volt battery in the battery
compartment.
(2) Turn on power 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.

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4 / F NO. 415, Jung-Jeng Rd., 238 Shu-Lin Chien, Taipei, Taiwan
E-Mail : [email protected]
http : / / www.centertek.com
320-01
CENTER TECHNOLOGY CORP.