ERICSSON TELEPHONE
No's O/815 & O/816

IRON CASED MAGNETO TELEPHONE

FOR USE IN MINES AND EXPOSED POSITIONS
WATERTIGHT AND EXPLOSION-PROOF

CASEWORK
Cast iron, enamelled black, with wide machined flanges on cover and case to render the instrument flame-proof.

RECEIVERS
Two double-pole receivers are provided, held normally in a rigid position by means of cradles.

TRANSMITTER
Capsule pattern, protected by moisture-proof shield and metal grid.

SWITCH
For connecting speaking battery. The switch is automatically operated when the receivers are raised for use.

TERMINALS
These are mounted in a separate compartment which can be sealed up with compound. Terminals are provided for an extension bell and for external batteries if required.

CONNECTIONS
A diagram is supplied with each instrument.

BATTERY
Two large-size primary cells are provided for the speaking battery.

TYPES
No. O/815 - Bridging type. For use up to five instruments in parallel.
No. O/816 - Heavy Bridging type. For use up to 30 instruments in parallel.

GENERATOR
Armature insulated from frame.
No. O/815 4-magnet pattern.
No. O/816 Special heavy bridging pattern.

RINGER
Gongs mounted outside the main case, well protected.
No. O/815 - 1000 ohms resistance
No. O/816 - 2000 ohms resistance

INDUCTION COIL
This is arranged so that the primary and secondary coils cannot be reversed.

PROTECTOR
An efficient instrument protector is fitted, guarding against lightning or other high-tension disturbances.

DIMENSIONS
Length 1 ft. 4 inches, width 1ft. 03 inch, depth 9 inches.

WEIGHT
76 lbs. (approximate)

Taken from the Ericsson Telephone Catalogue 1912

Last revised: April 10, 2000