| 摘要 |
A protection circuit employing a pair of SCR devices cross coupled between a telephone line tip conductor and ring conductor. The SCR devices are of the type providing internal semiconductor resistors between the gate and cathode terminals for sensing overcurrents in the telephone line conductors, and providing voltage sensitive semiconductor regions so that the SCR devices are sensitive to overvoltages on the telephone line conductors. When employed with a telephone line termination transformer, the internal resistor of one SCR device provides the series resistance, together with the transformer winding resistance, for reliably allowing the other SCR device to be triggered into conduction and remain in a latched condition in response to an overcurrent condition.
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