| 摘要 |
985,528. Electrotherapeutic appliances. S. YAMASHIKI. March 22, 1962, No. 11044/62. Heading A5R. The natural waveform transmitted through a nerve is a highly damped L.F. and this is simulated in the output of an electrotherapeutic appliance but, in order to avoid pain, a highfrequency wave is superimposed upon it. In the valve circuit shown a series of damped L.F. waves is obtained from the valve V1, connected as a blocking oscillator, and tuned by the condenser C and feed-back transformer T. A separate oscillation generator O.S, giving an output of between 20 and 100 kilocycles per second, is also connected into the circuit so that its output can be combined with that of valve V1 in the double triode V2 and the patient is connected across the load resistance at P. Circuits incorporating transistors are also described and in these a transistor is connected as a blocking oscillator to provide the low-frequency and the high-frequency component is obtained by, in effect, tuning the output transformer. In order to avoid excessive voltage drop when the patient is connected to the output, in the transistor circuits, the electrodes are connected respectively to the slider and one end of a potentiometer connected across the output. A 1000 ohm resistor is then also connected between the slider and the other end of the potentiometer. |
