Defibrillator with diode protection for capacitor-charging circuit - incorporates additional diodes with faster switching capability in series on secondary side of ultrasonic-frequency transformer

摘要

The charging circuit is protected by a high-voltage flyback diode (16) in parallel with the storage capacitor (2) against negative phasing of the defibrillation pulse connected by a switching device (4) through a choke (3) to external body electrodes (8, 9). To protect the voltage-doubling circuit (5) the sec. winding (18) of its transformer (19) is AC-coupled (22) to the junction (17) of two further diodes (14, 15) with higher breakdown threshold voltage, connected in series across the capacitor (2). A transient increase in voltage across the slower flyback diode cannot consequently lead to a destructive current through these diodes. ADVANTAGE - The circuit operating at around 30 kHz to reduce charging time and transformer wt. is protected against abrupt voltage increase due to short-circuit defibrillation.