Magnetic amplifiers of the balance detector type

IN PRACTICAL APPLICATIONS of electronic amplifiers in the field of electrical measurements and control problems two serious disadvantages of tube amplifiers must be considered. First, the life of vacuum tubes is limited, and second, shocks or vibrations are dangerous to such tubes. In order to maintain the various advantages introduced by suitable use of electronic amplifiers and to avoid the serious disadvantages mentioned, a tubeless amplifier has been developed in different countries, namely, the magnetic amplifier, also called d-c controlled reactor, saturable reactor, and transductor. This amplifier consists of electric and saturable magnetic circuits so interlinked that a direct current controls the reactance of an a-c circuit. The magnetic amplifier, which is a real d-c amplifier containing no moving parts and not requiring any servicing, will be of great importance in future development of numerous technical fields offering rough working conditions. This amplifier will undoubtedly have extensive use, chiefly in the electrical control of military equipment, in commerce, and for control of various manufacturing processes and automatic devices for private use.