If you want or need to telephone in areas where this is normally not possible, you need a sound-powered telephone system. Operation without external power supply and complex equipment, sound-powered telephony is ideal for communications whenever there is no power supply available, e.g. at blast furnaces, in tunnelling or mining, or offshore on oil rigs or high-sea steamers, and provides a direct connection to the switchboard, base, bridge or colleagues on the surface. Or wherever. This surprisingly easy, but effective method is already used widely to call for material, report faults or save lives. The howl-call telephone is a soundpowered device with highly efficient dynamic transmitter and receiver capsules offering communication without power supply. The call signal is generated by turning the rotary knob with an audio frequency dynamo. All telephones are equipped with an extremely sturdy, impact-resistant and weatherproof housing and have successfully proven their worth in years of operation in mining, tunnelling, on building sites and in industrial operations. 10 km range
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sheet (PDF) EEx
Examination Certificates (PDF) User
Manual (PDF) 