Abstract: A speech synthesized answering circuit for use with a telepone subscriber station. A microprocessor control circuit monitors a telephone line for detection of a predetermined number of ringing signal bursts. A read-only-memory contains a vocabulary of digitized words. The microprocessor answers the line and forms a telephone answering message by retrieving selected digitized words from the read-only-memory. This message is transferred to a speech processor which converts it to analog format and couples it onto the calling telephone line.

Abstract: A speech synthesized time announcement circuit for use with a telephone line control circuit. Upon detection of a predetermined number of ringing signal bursts or a predetermined keypad provided data pattern or a predetermined time period, a control microprocessor determines the current time of day and forms a time-of-day message by retrieving selected digitized words from a read-only memory. This message is transferred to a speech processor which converts it to analog format. If the time of day request was received over a telephone line, the control microprocessor causes the speech processor to answer the line and couple the time-of-day message onto the line. If the request was received by internal interrupt or via the keypad, the control processor causes the speech microprocessor to announce the message locally by applying it to a local speaker.

Abstract: A circuit which monitors air flow by comparing the speed of a fan to a predetermined frequency. A Hall effect device detects magnetic pulses representative of the fan speed and provides a corresponding electrical signal. This signal is compared with a predetermined threshold frequency by a retriggerable monostable multivibrator. A digital delay circuit isolates pace conditions and a relay circuit provides an indication of the fan speed status.