Intercom for ML070 Track Maintenance
Vehicle
The scope was to design and build a simple but reliable intercom, to
be used between the two driver's cabs and the operator's console in the
trailer car.
Sufficient audio output is ensured by the choice of PA stage and speaker.
Balanced audio lines are used between the three units and between the
unit and the microphone to minimize any hum or interference.
An additional feature is included which, if a pushbutton is pressed on
one of the units, sets off an alarm at the other two units. This is to
ensure that contact can be established, even if the volume setting has
been turned down. This feature utilizes a low frequency tone on the same
audio pair as the speech and, consequenctly,
only one speech pair is required to connect the three units. |
