2N Lift emergency phone 2N SingleTalk - Manual, 1514 v6.3.0 - Manual (Page 39)

Installation
– Compact Version
2.6
38
Notes
 5 - 24 dc voltage of any polarity can be used. Make sure that the power
supply is backed up properly.
 Where activation from multiple places is necessary, voltage control can be
combined with buttons.
 A buzzer or horn can be connected in parallel, see the figure to the right.
Inversion Voltage Control
Voltage Activation
The figure to the right shows a configuration where voltage is present and
activation is caused by non-presence of voltage.