Ultrasonic generator for medical use e.g. echography - includes signal generator and variable modulator feeding signal to small transducer for localised treatment

摘要

The ultrasonic appts. includes a 28 kHz sine wave signal generator whose output is applied to the input of a modulator (11). A modulation clock circuit (12) is connected to a number of switched networks (13-17) comprising resistor (131) and switches (132) in series. The switched networks may be used to control the frequency of the clock circuit. The clock circuit output is fed to a programmable divider (18). The divider is controlled by a second set of switched circuits (179-185) to give division factors from 180 to 12. The divider output is connected via a switch (110) to the modulator, to modulate the ultrasonic signal. The modulated signal is fed via a power amplifier (19) to an ultrasonic transducer which is used to apply the signal to a small area on the patient's body.