| 摘要 |
1,168,610. Spark erosion. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 13 Oct., 1966 [16 Oct., 1965], No. 30847/69. Divided out of 1,167,853. Heading B3V. [Also in Division H3] In the spark erosion of a workpiece 35, a capacitor 61, 62 is connected between the workpiece and an electrode 33 and is charged from a pulsed voltage source 40, each charge period commencing with the beginning of a pulse and terminating during discharge across the spark gap. The capacitance 62 may be the parasitic capacitance between the electrode and workpiece and the variable capacitance 61 may be the anode capacitance of the pentode 33. The grid of this pentode is controlled by a double tetrode 62 which also controls the grid of a cathode follower pentode 31. This grid receives pulses from tetrode 30 supplied from the pulse source 40. During a spark discharge, the resulting voltage drop across the spark gap triggers the grid of double tetrode 32 causing it to conduct. This in turn biases pentodes 31, 33 to cut-off whereby the charging of the capacitors ceases. Specific examples are given of the values of the components used in the circuit. |
