| 摘要 |
A voltage actuated switch coupled to a telephone line for actuating a tape recorder or other apparatus with a transistor in series with the apparatus and a power source; a circuit within the switch biases the transistor into conduction when the telephone line voltage is low, "off-hook" causing the tape recorder or apparatus to operate; when the telephone line voltage is high, "on-hook", the circuit biases the transistor off, current ceases to flow to the tape recorder or apparatus that is then turned off.
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