Specifications
4
A-M Systems, Inc.
131 Business Park Loop, P.O. Box 850 Carlsborg, Wa 98324
Telophone: 800-426-1306 * 360-683-8300 * FAX: 360-683-3525
E-mail: sales@a-msystems.com * Website: http://www.a-msystems.com
Theory of Operation
One of two inputs may be selected using the CHANNEL switch. The selected input is
then amplified according to the setting of the GAIN switch. After amplification, the signal
can be filtered at the frequency of the power line by use of the NOTCH filter.
Particular narrow ranges of frequencies of the processed signal can then be boosted or
attenuated using the GRAPHIC EQUALIZER. Maximum boost or attenuation is +/-
12dB, centered on the frequency indicated under each slide knob.
The output of the graphic equalizer feeds directly into the VOLUME control and LINE
OUTput. Setting the LINE OUT Switch to
Variable
will produce the processed signal with
the additional variable gain provided by the VOLUME control at the BNC jack. Setting
the LINE OUT Switch to
Fixed
will provide the processed signal at the gain indicated by
the GAIN switch (taken prior to the GRAPHIC EQUALIZER) at the BNC output jack.
The signal is then amplified using a power amplifier circuit in order to provide enough
current to drive either the internal speaker or an external user-supplied set of headphones.
Inserting a mini-headphones plug into the headphones jack will disable the internal
speaker.
Figure 1. Main circuit block diagram
GAIN
NOTCH FILTER
50/60Hz
OFF
ON
FIXED
LINE
OUT
VARIA BLE
POWER
INPUT
AMPLIFIER
AMPLIFIER
HEADPHONES
INTERNAL
LOUDSPEAKE
R
INPUT 1
INPUT 2
x1
x10
x100
GRAPHIC
EQUALIZER
HEADPHONE
JACK
VOLUME
160Hz 400Hz 800Hz 1.6kHz 3.2kHz 8.0kHz