Chapter I: Preface

Among all the applications of electricity to domestic or commercial uses, few are as widespread as the electric bell. Practically every building used for a dwelling, storage or manufacture requires an electric bell, annunciator or alarm system.

This book was written to explain in practical language how an electric bell system operates and how it is installed; its success shown by its large sale has resulted in this new edition which brings the subject up to date.

Many new diagrams of annunciator and burglar alarm systems have been added, together with descriptions and illustrations of wiring elevators for electric bells, wiring for door openers, the use of transformers for furnishing suitable ringing current from electric light circuits; and high voltage bells intended to be used on other than the customary low voltage battery circuits.

The author expresses his acknowledgment to the Western Electric Company for diagrams of door opener circuits in connection with their interphone systems, to Edwards and Company of New York for diagrams of fire alarms, burglar alarms and annunciators, and to the Westinghouse Company for illustrations of bell-ringing transformers.

CONTENTS

INTRODUCTION

PAGE
Introduction. The principle of an electric bell. ix

CHAPTER I

The Leclanche cell--Polarization--Setting tip--The dry
cell--The gravity cell--Connecting up cells 1

CHAPTER II

The single stroke bell--The shunt bell--The differential
bell--The continuous ring bell--The waterproof bell--Forms
of gongs--The buzzer--Long distance bells--The relay--The
push--Three point or double contact push--Floor push--Door
pull--Indicating push 9

CHAPTER III

Bell wires--Joints--Running wires--How to put up a door
bell--Combinations of bells, pushes and batteries--Faults
in bells, faults in wiring--How to locate and remedy faults 23

CHAPTER IV

Fire alarms--Thermostats--Metallic thermostats--Mercury
thermostat--How to connect thermostats--Water level
indicators--Burglar alarms--Open and closed circuit
alarms--Window, door and shade springs--Alarm matting--Yale
lock alarm--Door trip alarm 40

CHAPTER V

The annunciator drop--The needle or arrow drop--The pendulum
drop--Wiring up annunciators--Return or fire call
systems--Double wire system--Western Electric single wire
system 55