IRON CASED MAGNETO TELEPHONE
FOR USE IN MINES AND EXPOSED POSITIONS
WATERTIGHT AND EXPLOSION-PROOF
Cast iron, enamelled black, with wide machined flanges on cover and case to render the instrument flame-proof.
Two double-pole receivers are provided, held normally in a rigid position by means of cradles.
Capsule pattern, protected by moisture-proof shield and metal grid.
For connecting speaking battery. The switch is automatically operated when the receivers are raised for use.
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.
A diagram is supplied with each instrument.
Two large-size primary cells are provided for the speaking battery.
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.
Armature insulated from frame.
No. O/815 4-magnet pattern.
No. O/816 Special heavy bridging pattern.
Gongs mounted outside the main case, well protected.
No. O/815 - 1000 ohms resistance
No. O/816 - 2000 ohms resistance
This is arranged so that the primary and secondary coils cannot be reversed.
An efficient instrument protector is fitted, guarding against lightning or other high-tension disturbances.
Length 1 ft. 4 inches, width 1ft. 03 inch, depth 9 inches.
76 lbs. (approximate)
Taken from the Ericsson Telephone Catalogue 1912
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