GB651951A - Improvements in or relating to an electro-medical apparatus - Google Patents

Abstract

651,951. Electrotherapeutic apparatus. NEMEC, H. Nov. 10, 1948, No. 29181. [Class 81(ii)] Electromedical apparatus comprises two separate sources of variable current energizing separate pairs of electrodes and having inter-related control means so that interaction of the fields produced gives a desired stimulation in the depth of the tissue without influencing the surface areas. In the embodiment described a power transformer 1 supplies two separate rectifying and smoothing circuits, each giving a direct current across a potentiometer, from which an output for electrodes 11, 12 and 13, 14 is taken through a control circuit consisting of resistors 2, 3, condensers 5, 6 and coupled, mechanically driven contacts 7, 8, 9. Contact 7 is closed to charge condenser 5 and then opened, so giving a gradual increase of current between electrodes 11, 12, followed by an exponential decrease. as in curve 1, Fig. 2. Contacts 8, 9 are closed during charging of condenser 6 and, at a time before the opening of contacts 7, both are opened and contact 9 moves from position 10 to 10<1>. In this case the increase in current through electrodes 13, 14 is followed by a sudden decrease, as in curve 2, Fig. 2. The electrodes are so placed that their fields 15, 16, Fig. 1, overlap in opposition in the area 17 and although the rates of increase and decrease of the individual fields are not sufficient to produce any stimulation, the resultant field, (see curve 3, Fig. 2,) varies in such a way as to produce the desired effect in the internal area 17