GB1390732A - Electrotherapy machines - Google Patents

Abstract

1390732 Electrotherapy device NEURO SYSTEMS Inc 11 Jan 1973 1534/73 Heading A5R [Also in Division H1] An electrotherapy device, particularly for inducing sleep, comprises a first circuit producing a train of electric pulses, and a second circuit responsive to said first circuit to produce on electrodes 8, 9 a train of periodic bursts of alternating current with intervening dwell periods, each of said bursts comprising a plurality of positive and negative pulses of similar amplitude and having a zero vectorial current run whereby to avoid impressing net direct current on a patient. A relaxation oscillator comprising an R-C timing circuit 21, 22, 23 (or 24 or 25) and a unijunction transistor 20 activates a monostable multivibrator, comprising dual gate 29 and R-C timer 31, 32, 33, to repetitively open transistor gate 34 for the monostable period whereby an oscillator is energised repetitively for periods corresponding to the monostable period. The oscillator comprises a dual gate 36 with the output of each gate fed to the input of the other gate via R-C tine constant circuits, the output of the oscillator passing to a push-pull amplifier 46, 47 feeding electrodes 89 via a manually adjustable attenuator 51 and a timer attenuator 11, the instantaneous power output being limited by resistors 35, 44, 45. A neon 52 and a loudspeaker 54 provide visual and auditory stimulation. The device 11 acts to provide a gradual increase in signal current amplitude over a fixed period, e.g. 5 minutes, to a maximum level at which it remains for a preselected period, e.g. up to 50 minutes, whereafter a gradual decrease to zero occurs over a further fixed period, e.g. 5 minutes. The timer 11, Figure 6 (not shown) comprises a clockwork mechanism (60) driving a shaft (61) carrying wiper arms (67) and (71) of variable resistors (62) (63). On starting, wiper (71) runs over a high resistance part of the track of resistor (63) whilst wiper (67) runs over a low resistance part of the track of resistor (62). After the current increase period both wipers run over low resistance track portions for the pre-selected period, after which wiper (71) continues over its lowresistance track whilst wiper (67) runs over a high resistance track to reduce the current amplitude to zero. The period at maximum current amplitude is selected by rotating a winder knob (69) of mechanism (60) to a selected point on a time scale, such movement rotating the track of resistor (63) relative to its wiper and relative to the resistor (62), resistor (63) being retained in this position by a spring (74) as the mechanism (60) runs down. Movement of knob (69) from the zero position closes a switch 12 (68) in the power supply line to the alternating current burst generator.