A very popular type of switchboard, being so simple in build, apparatus and operation.
The case is made of fine hardwood matt polished, and the size is standardised for all equipment's up to 20 lines.
The N4815D hand-restored drop indicators in the lines are 1000 ohms and are mounted in strips.
The indicators are permanently bridged across the lines so that they also give the clearing signal, their impedance is high and prevents any appreciable loss of speech currents.
The jacks are in strips fitted with removable labels numbered to correspond with the indicators.
The connecting cords are fitted with a plug at each end, thus providing straight through connections so that conversations cannot be interfered with by the operator.
A single cord and plug is provided for operating purposes.
For the operator's use a separate magneto telephone is required and should be installed by the side of the switchboard, a suitable instrument being telephone N2204.
The night alarm is fitted inside and the "on" and "off" switch outside the case.
These switchboards may also be used for earth circuits.
Last revised: October 12, 2019