| 摘要 |
An electronic switch for use in the tip and ring circuit of a rotary dial telephone pulsing system is disclosed. The electronic switch is a functional replacement for a single pole, double throw electromechanical pulsing relay having normally open and normally closed output terminals, with the state of the output terminals being reversed in response to the connection of an external impedance load to an input sensing node. Normally open and normally closed output nodes are driven by first and second output switching circuits. The operating states of the first and second output switching circuits are reversed in response to a switching signal generated by a binary switch. The binary switch is biased off with no switching signal being produced in the absence of the external impedance load so that one output terminal is normally open and the other output terminal is normally closed. When the external impedance load is connected to the sensing node, the switching signal is generated, thereby reversing the operating states of the output switching circuits. |
