| 摘要 |
933,028. Electro-plating circuits. WESTING- HOUSE ELECTRIC CORPORATION. May 15, 1962 [June 27, 1961], No. 18677/62. Class 41. [Also in Group XXXV] An electro-plating system providing periodically reversed current flow to a bath from a polyphase A.C. source comprises a transformer 14 having a plurality of first controlled rectifiers 16, 18, 20 connected to each phase poled to conduct in one direction, and at least one second controlled rectifier 24 connected reversely across one or more of the first rectifiers. The first rectifiers are held non-conducting by a negative bias applied across a resistor 66 to which is added a first square wave through a secondary winding VS1 of half supply frequency from a bi-stable circuit 90 triggering rectifiers 93, 94 into a transformer 96, giving a varying negative potential. The first rectifiers are fired by superimposing on this potential pulses from circuits 50, 60, 70 which operate by charging a capacitor, e.g. 54 through a resistor 55 which fires rectifier 57 through a resistor 58, the amplitude being clipped by a Zener diode 52. The pulse circuits are controlled by a common resistor 69. The second rectifier is fired in a similar manner by pulses from a circuit 80 added to a second square wave displaced by 180 degrees from another secondary winding VS2 and fixed bias across a resistor 104. The system gives three positive and one negative past cycles every two cycles of the supply. Specification 906,524 is referred to. |
