Call indicator and memory for half:duplex exchanges - has bistable flip flop keeping callers light on after message end

摘要

The call indicator and memory, for half-duplex exchanges, indicates the calling subscriber with eg a flashing light that also keeps the engaged light associated with the calling subscriber alight even after the message has ended so that the called subscriber can identify the caller requiring an answer. - Each connection circuit has a bistable flip flop (T1,T2). After a given time the flip flop changes state and reverse biases the diode (Gr9) that connects the flashing pulses (J) to the lights