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ApplicationNo. 410439 filed on 09/21/1989
US Classes:379/412, Protective circuit361/91.7, Protection by snubber circuitry361/119, In communication systems379/331, Having protective circuit379/413Power supply (e.g., battery feed)
ExaminersPrimary: Dwyer, James L.
Assistant: Shehata, Magdy W.
Attorney, Agent or Firm
International ClassesH02H 009/04
Foreign Application Priority Data1988-11-11 GB
AbstractAn overvoltage protection circuit for a pair of conductors carrying a balanced signal includes two similar protection elements connected in series between the conductors and two equal value resistors respectively connected in parallel with the elements, so that the junction point of the two elements is at a voltage midway between the voltages on the conductors and the protection elements present equal capacitances to the conductors. A third protection element is connected from the junction point of the two elements to ground to protect against excessive voltages relative to ground on the conductors. The voltage division provided by the resistors may be adjusted to improve the balance of the capacitances presented by the two protection elements.