US2252941A - Oscillating circuits for electrotherapeutics - Google Patents

Description

g- 19, 1941- E. MITTELMANN 2,252,941

OSCILLATING CIRCUITS FOR ELECTROTHERAPEUTICS Filed May 24, 1940 Patented Aug. 19, 1941 OSCILLATING CIRCUITS FOR ELECTRO- THERAPEUTICS Eugene Mittelmann, Chicago, Ill., assignor of onethird to Henri C. Marcy and one-third to Le Roy W. F. Roedell, both of Chicago, 111.

Application May 24, 1940, Serial No. 336,988

3 Claims.

The invention relates to oscillating circuits and particularly to those used in diathermy and electro-surgery.

In short wave diathermy and high frequency surgery only a fraction of the available high frequency power or total power output of the oscillating tubes is utilized in the patients circuit, but due to the unfavorable matching conditions, by reason of the fact that the impedance of the load is lower than the impedance of the generator, tubes of high power output have to be used.

The necessity for usinghigh power output tubes with their rectifier circuits and power supply equipments makes it diflicult to build portable short wave diathermy equipments which are relatively small in weight yet meet all the requirements as far as the useful power output is concerned.

It is an object of my invention to provide circuits in connection with electronic tubes which enable the design of highly eflicient oscillators for the aforementioned purposes.

Another object is the provision of a high frequency oscillator wherein a small transformer comprising a single winding may be used which yields the same power for the load circuit as now obtainable with a transformer having a double or center tapped winding.

A still further object constitutes the provision of a high frequency oscillator wherein the oscillating tubes are alternately energized even though a single winding transformer is used.

Other and equally important objects will become apparent from a perusal of the invention which comprises the means described in the following specification, particularly pointed out in the claims forming a part thereof, and illustrated in the accompanying drawing, in which the figure is a diagram of an oscillating circuit embodying my invention.

As shown in the figure, the oscillator tubes l and 2 have a common tank circuit constituted by the inductances 3, 4 and the capacities 5, 6. The capacity 5 has a very low impedance in comparison to the impedance of the inductances 3, 4 and acts as a short circuit for the oscillating circuit.

The tank circuit is tuned by the variable condenser 6. The filaments of the oscillating tubes are heated by two independent filament transformers I and 8, respectively, or by any other suitable source of power supply.

Between the two filaments, connected in series, is the secondary or high tension winding of the transformer 9. The ends of the high tension transformer windings are connected crossway to the inner ends of the inductances 3 and 4, respectively. Thus, in one half cycle of a full period of the supply frequency, the tube I will oscillate, having the plate potential positive in respect to the filament potential. In the next half cycle tube 2 will oscillate as at this time the anode of tube 2 is energized by a positive plate potential. In each half cycle the tank circuit forms part of a complete oscillator circuit, including the coupling condensers l2, l3 and the grid leak resistances l0, II, respectively.

The load I! is shown as coupled through capacities M to the treatment electrodes 16. Any other suitable type of coupling between load and oscillator might be selected, depending upon the nature and electrical characteristic of the load. The use of such an oscillator is, of course, not limited to the purpose of short wave diathermy, but can be used with advantages everywhere, where signals of modulation, for example, are required, as for instance in the ship to ship, or ship to shore service of maritime transmitters.

While the drawing shows an embodiment of my invention, various changes and alterations may be made.

I, therefore, do not limit myself to the details of arrangement, as shown, but include all changes and variations which fairly fall within the scope of the invention as defined in the appended claims.

I claim:

1. In an oscillating circuit, a split inductance, a pair of oscillating tubes, said inductance being connected at its ends to the plates of said tubes, separate source of energy for the filaments of said tubes, and a single winding plate transformer connected between the filaments of said tubes, the filaments of each tube being connected to the inner end of that portion of the split inductance which is adjacent to the plate of the other tube.

2. In an oscillating circuit, a split inductance, a pair of oscillating tubes, said inductance being connected at its ends to the plates of said tubes, and a single winding plate transformer, each end of said transformer being connected to the filament of one tube and to that portion of the split inductance whose end is connected to the plate of the other tube.

3. In an oscillating circuit, an inductance split in two portions, a condenser interposed between the portions of said inductance, a pair of oscillating tubes, said inductance being connected at its ends to the plates of said tubes, and a single winding plate transformer, each end of said transformer being connected to the filament of one tube and to that portion of said inductance which is adjacent to the other tube.

EUGENE MITTELMANN.

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