ACR&Artex Megaphone - Manual (Page 4)

4 Y1-03-0014 Rev. AC
SECTION 1 – DESCRIPTION
The ACR/EM-1A or ACR/EM-1D is a battery operated solid state megaphone specifically
developed for use in enclosed areas such as in the interior of an aircraft or ship cabin. It
has been designed to minimize regenerative acoustic feedback that results in whistling and
other oscillations of this nature. It has a 90° sound projection angle to direct the sound to
persons in its immediate vicinity, as well as in the rear sections of any aircraft. The amplifier
frequency band-pass has been selected to produce a crisp, clear reproduction of voice
signals. The operating power level is also sufficient to provide adequate sound under high
ambient noise level conditions without being over-powering. Specific attention has been
given to the physical size so that it can be used effectively in a crowded environment.
The integrated circuit amplifier only uses a small current when turned “ON”. This extends the
life of the batteries so that several hours of operation may be expected when used normally
in an intermittent manner. A simplified block diagram of the megaphone is shown in Figure
1 (shown on page 5).
The ACR/EM-1A & ACR/EM-1D are the same except for installed options:
1.1 Options Matrix
MODEL MANUAL GAIN ALARM ACTUATOR BATTERY MONITOR
Visual Audible
ACR/EM-1A Yes Yes Yes No
ACR/EM-1D Yes No Yes Yes
SECTION 2 – OPERATION
A siren, incorporated into the megaphone, is automatically activated by unplugging the alarm
plug pin. (ACR/EM-1A only)
Note: A long lanyard with an alarm plug pin is supplied with the megaphone for use
as an anti-theft alarm (optional).
Squeezing the handle stops the siren, and the megaphone is ready for use. Re-insert the
alarm pin so that the alarm will not be reactivated when the handle is released.
Hold the megaphone in one hand. Place your mouth almost in contact with the microphone
mouthpiece at the rear of the assembly. Squeeze the handle, which will flex slightly, turning
the megaphone “ON” and speak slowly with loud, crisp, clear tones.
Adjust the volume control knob to a suitable sound level. The volume control may be adjusted
with the thumb of the same hand holding the megaphone.
When not in use, carry the megaphone by the neck strap, attached to top of unit.
2.1 Battery Monitor
Two types of battery monitors are available on the ACR/EM-1 series megaphones.
Visual -
when the megaphone is activated by squeezing the handle, a green LED
indication means the remaining battery capacity is greater than 50% of initial capacity. If the
green LED is out, replace batteries.
Audible -
when the megaphone is activated by squeezing the handle, a chirp heard in
the speaker means the remaining battery capacity is greater than 50% of initial capacity. If
the beep is not present, replace the battery. (ACR/EM-1D only)