摘要 |
A one-to-one line switching system for switching between a hot line and a standby line in a one-to-one correspondence. To enable removal of a switching unit while in use, from a mother board for change over or repair, a pair of switching units (1 and 2 or 3 and 4) is provided at the transmitting part and at the receiving part, respectively, the earth element in one of the pair being connected to the other of the pair and the other of the pair being pulled up by a voltage, whereby, when one of the pair in use is removed, the other of the pair can pass the input signal.
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