Timed diathermocautery comprising a timer unaffected by disturbances of electromagnetic origin

Claim 1

The combination of a timing device and a diathermocautery apparatus for use on a patient and including a power supply in which power is selectively supplied to a load from said power supply, said apparatus having a switch movable between an operate position and a non-operate position, said timing device being immune to electromagnetic disturbances and comprising: comparator means for establishing threshold levels of a timing voltage above which said power is supplied to said load; timer means for supplying said timing voltage to said comparator means, said timer means comprising a series connected capacitance and resistance in parallel across said power supply; and current duration limiting means for activating said timer means when said switch is moved to said operate position and for limiting the amount of time that said timing voltage is supplied to said comparator means when said switch is in said operate position and for providing a set time before which said timer means may be reactivated; whereby said timer means may not be accidentally reactivated prior to said set time because of dirty or faulty switch contacts or because of vibrations, and whereby electromagnetic disturbances may not affect the timing device as in electronic timing devices of the integrated circuit type.