Railroad Car Personal Emergency Intercom
PEI Description
Our MPL-2 microphone with integral pre-amplifier, line-driver, talk button and talkback speaker, is available in a variety of custom metal enclosures to fit most railroad car installation requirements. This mic has the important advantage of overriding all electrical noise in transit vehicles. This property permits placing microphones conveniently accessible to passengers in any location within the transit vehicle.
Model MPL-2 provides distortion free output in extremely loud sound fields, over 110 dB SPL. The electronic circuit amplifies the signal and filters the sound to cover the voice range while removing extraneous vehicle noises. The line driver boosts the output power for routing to the central control module of the public address or monitoring system.
Built for transit use, the MPL-2 meets the stringent environmental needs of wide temperature range, sparks from electrical commutation, constant vibration, and long term use. Over 12,000 are installed in the passenger rail systems around the United States.
The MPL-2 can be modified to meet many special requirements.
PEI Microphone and Line Driver Specifications
Microphone
- Electret element w/FET
- Pattern: Omnidirectional
- Bias: 2 to 5 volts
- Max Sound level: 120dB SPL
- Integral moisture screen
- Acoustical shield
Pre-Amplifier System
- Sensitivity: 2 Vrms/100dB SPL
- Overload Level: - 19 Vpp @ 24 Vdc - 8 Vpp @ 12 Vdc
- Frequency Response:150Hz-10kHz
- 18dB/oct HP and LP Filters
- Distortion: <2% up to clipping
- Noise: -80 dB re 1 Vrms
Line Driver
- Output Impedance: 100 ohms
- Recommended load: 1k-10 k ohm
- Withstands continuous short circuit
- Unconditionally stable
Supply Requirements
- Nominal power: 12 Vdc
- Operates from 6 to 36 Vdc
Transient Protection
- Output Line decoupling
- Input and output RF filters
- All leads safe for transients of
- +/- 100 Volt, 100 microsecond
Physical
- Size: 2.75 x 1.45 inches
- SMT and thru-hole components
- Coated Circuit Board.
- Rubber Grommet mounts
- All component references marked
- Manufactured to IPC-610 standards
Environmental
- Temperature: -30 to + 65 deg Celsius
- Humidity: 5% to 90% non-condensing
- Vibration: 8G's for 20 ms
- Splash Proof