Single-ended self-balancing magnetic amplifiers for changing the effective impedance of ink recorders

Announcement was made in 1952 of a magnetic amplifier of the self-balancing potentiometer type1 combining the very stable operating conditions of d-c instrument transformers2,3 with the unique features of self-balancing potentiometer devices and negative-feedback amplifiers. Thus the door was opened to widespread application of such ¿self-balancing¿ magnetic amplifiers4 in fields which are far beyond the capabilities of the conventional magnetic-amplifier circuits. Actually, since then, this subject has engaged the attention of many research and development groups with regard to design5,6 and analytical investigations.7¿10 As a result of the development of various types of self-balancing magnetic-amplifier push-pull circuits utilizing either differential external feedback11,12 or self-saturation,13,14 the field of application is continually being broadened.