 | Circuits, Formulas and Tables Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 201 p.) |
 |  | 2. Bell Circuits |
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2.1. Direct-current Bell
Direct-current bell to be actuated
from one place
Direct-current bell to be actuated
from two places
Bell installation for reciprocal
calls
Sell installation for reciprocal
calls with key change-over switch
Bell installation for reciprocal
calls with switch-on push-button, line-saving
Bell installation for reciprocal
calls,
line-saving
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