Magnetic amplifiers

Direct current controlled transductors, now known as magnetic amplifiers, were used successfully by the Germans in the 1939-1945 war for the amplification and mixing of powers down to a microwatt. The desire to know more about their operations than has been given in various periodicals prompted this thesis. An explanation of magnetic amplifier action is given and the waveforms of flux and output current predicted. The behaviour of circuits containing a magnetic amplifier is then explained by the use of waveforms and a mathematical investigation is made. A use for a magnetic amplifier in an oscillator tank circuit is described. Graphs of the characteristics of the magnetic amplifier and photographs of the waveforms are shown and the observed waveforms compared with the predicted ones. A sensitivity test on three circuits containing a magnetic amplifier is described and results given showing that by placing a condenser across the supply windings increases the sensitivity considerably but decreases the power amplification. The proper way to secure a thorough understanding of the properties of the magnetic amplifier by the use of an oscilloscope is discussed and the thesis concludes by listing the advantages and disadvantages of a magnetic amplifier. The mathematical approach to the solution of the magnetic amplifier problem using Frolich's equation for the magnetization curve is given in a special appendix.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat