1200/2200 Sound Level Meter Operator’s Manual
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Operation
4.4 Data Recording:
The model 1200 has a DC output that is linearly related to the deciBel
reading on the LCD display by 16.7mV/dB (1V/60dB).
This output, capable of driving up to 100 feet of shielded or twisted pair
cable, is intended for use with a chart recorder or data acquisition device
that has a high input impedance. The output impedance is 1000 ohms.
Recorder input impedance may cause loading of this output, which should
be taken into account. Multiplication factors for the above numbers are
given below for various recorder input impedances.
INPUT IMPEDANCE
MULTIPLY DC VOLTAGE
OF RECORDER:
BY:
10 KOHM
1.100
20 KOHM
1.050
50 KOHM
1.020
100 KOHM
1.010
1200/2200 Sound Level Meter Operator’s Manual
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Figure 5. 1200/2200 Block Diagram
5. TECHNICAL INFORMATION
5.1 Principles of Operation:
The Quest model 1200 uses low noise, low power analog and digital
integrated circuirty to ensure long battery life, maximum stability, and
superior reliability over a wide range of environmental conditions. Figure
5 is a block diagram of the model 1200/2200’s internal circuit operations.
5.2 Microphone:
The model 1200 is designed to accept a prepolarized (electret)
Type 1 microphone Quest P/N #059-523 (BK #4936). The impedance of
this microphone is approximately 12pF. The microphone screws directly
onto either the remoteable preamp or the fixed microphone extension of
the meter case. A typical response curve for the Type 2 microphone is
shown in Figure 6.
The model 2200 is designed to accept a prepolarized (electret) Type 2
microphone Quest P/N #056-316 (QE7052). The impedance of this micro-
phone is approximately 15pF. The microphone screws directly onto either
the remoteable preamp or the fixed microphone extension of the meter
case. A typical response curve for the Type 2 microphone is shown in
Figure 7.
Technical Information
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