Japanese Patent JPS3810862

B1

928,922. Transistor oscillator circuits. PHILIPS ELECTRICAL INDUSTRIES Ltd. Sept. 23, 1960 [Sept. 26, 1959], No. 32774/60. Class 40 (6). A pulse generator comprises a transistor having in its output current circuit an inductance which determines the rate of rise of output current and which provides positive feed-back, the circuit also including a winding on a square loop core which, when the output current exceeds a predetermined value, changes its state and initiates the cutting off of the transistor. In Fig. 1 two transistors 1 and 2 conduct alternately and are connected to an output transformer 5 which determines the rate of rise of current in the transistors when they become conducting and which provide feed-back to the opposite bases. A square loop core 10 is threaded by the emitter circuit leads so that when the current is such that the core changes its state a sudden reduction in the primary voltage of the transformer 3 takes place so that a reversal of the state of conduction of the transistors is initiated. This prevents the current spike which normally occurs at this point in the cycle. In Fig. 3 (not shown) the square loop core windings are arranged in the circuit connection between the right-hand terminal of battery 7 and winding 3. In Fig. 4 positive feed-back is provided by capacitors 11 and 12 and two square loop cores are provided, the resetting of the cords being effected by the opposite circuit through a coupling loop 17. A single ended circuit (Fig. 5, not shown) comprises an auto transformer positive feed-back path and a biasing winding connected to the supply source to re-set the square loop core when the transistor is not conducting. A further embodiment (Fig. 6, not shown) uses positive feed-back from a transformer connected in series with the secondary of the output transformer and the load and a square loop core winding in the emitter circuit biased by a permanent magnet to one state when the transistor is non-conducting. Appropriate biasing is applied to the transistor to ensure starting. It is stated that the square loop core winding could alternatively be arranged in the base circuit.

JP3905260A

July 01, 1963

September 26, 1960

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H02M7/5383; H03K3/30

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