| 摘要 |
PURPOSE:To enable the reception of a tri-state data with a simple constitution, by operating an exclusive use diode switch and a rectifying circuit depending on an input signal whether it is a mark or a space and cutting off the said diode when the input signal is zero. CONSTITUTION:When a space signal of minus polarity is applied to a terminal 22 based on a terminal 21, diodes 29 and 31 are turned on, and an AC current from an oscillator 23 is transmitted to a transformer 35 via the diodes 29 and 31. The current is converted into a DC with a rectifying circuit 37 and a data signal with minus polarity is obtained at a terminal 41. When a mark signal with plus polarity is inputted, diodes 32 and 34 are turned on, the AC current from the oscillator 23 is rectified at a rectifying circuit 38 and a data signal with plus polarity is obtained at the output terminal 41. On the other hand, if the input data signal is zero, the diodes 29,31 and 32,34 are all turned off, the AC current from the transformer 24 is interrupted and the output at the output terminal 41 is also brought to zero. |
