Basic modules

4NPA. LF Interface Module

4NPA. LF Interface Module

At a Glance:

  • Low frequency (LF) control of third-party amplifiers in intercom systems
  • Connecting call stations with line control in public address systems
  • Low frequency call forwarding of/to radio module
  • Low frequency interface for external low frequency sources
  • Gate intercom (optional)

The DVS-21 is capable of connecting not just our own but also third-party de-vices. A low frequency connection and control through C and V points makes possible the use of the module 4NPA for four devices. In order to meet other control requirements the 24LI line module can also be used.

Application Description:

Application examples for intercom and public address systems with 4NPA
Fig. Application examples for intercom and public address systems with 4NPA

The 4NPA can be used for various applications.

With PA applications, for public address through a line-controlled call station, in addition to the 4NPA module also the line card 24LI and the amplifier V100 are required. The same applies for use with a signalling system (PABX) or radio modules.

For intercom functionality at least one further call station is necessary. This can be another third-party call station on the same or a second 4NPA module or a ProCom call station on a 4NSA module.

In standard use, a gate intercom is realized with ProCom call stations and the 4NSA module.

As alternative the gate intercom function can be realized with the 4NPA module and a third-party call station as gate call station. For this a ProCom call station connected over the 4NSA module and a line card 24LI are required. Here it must be taken into account that the third-party gate call station must have control points (-V and C points) to switch the microphone and the call station amplifier.

Further areas of application are LF control of external amplifiers as well as the LF connection of external sources (e.g. CD player).

Function Description:

The principle functions are illustrated in the following block diagram.

Block diagram 4NPA
Fig. Block diagram 4NPA

The 4NPA has four identical sets.

The -48 V output is fused with a cut-out fuse. If this is defective then a signal is generated through an opto-coupler.

The C point is required for switching on the call station amplifier. To use one less line, this can be switched using a solder bridge on the backplane over the mid-a/b output transmitter.

The microphone amplifier of a third-party call station can be switched on and off over the V point.

These points are switched using the ICS software.

The C and -V points are control requirements for third-party call stations. They are galvanically isolated by opto-couplers from the control circuit.

The La/b are connected to the output transformer. The incoming or outgoing ana-logue LF signal is converted analogue/digital by the codec.

The Front Plate Symbols and their Meaning:

The System Blinker The System Blinker
Addressing from processor taking place
I/O Input/Output
BUS output works as push-push operation with the system blinker
BUS input works as push-pull operation with the system blinker
↓↑ Sending/receiving status (depending on set)
LED blinking: LF signal being sent
LED lit: LF signal being received
Fuse Fuse(depending on set)
LED off: Fuse has been triggered

Technical Data:

Operating Voltage: 48 V (power level)
Operating Voltage: +/-5 V (control)
Feeding Current (48V): Max. 4x 1.5 A to the third-party call stations
LW Interfaces: 4x 300 Hz - 3400 Hz
Temperature Range: 0 °C to 45 °C
Weight: 300 g
Installation Height: 3HE
Installation Width: 6TE