| 摘要 |
PURPOSE:To detect a time signal accurately by arranging a circuit for detecing 880Hz as time signal of a radio or television, a circuit for detecting the non- signal state immediately before the time signal and a rising detection circuit for transmitting pulses according to outputs of both the detection circuits. CONSTITUTION:An operation amplifier 1 amplifies a vioice input sent from a radio or a television via a voice input terminal 11 and inputs it into an operation amplifier 3 after conversion to a voltage change with a circuit A. The non- signal output thereof is extended with a circuit B to obtain a non-signal detection output. Output of the operation amplifier 1 is branched into another operation amplifier 2 which inputs an 880Hz detection output into an AND circit 4. When the 880Hz detection output is ANDed with the non-signal detection output, voice constitutes a non- signal state which permits the outputting of 880Hz pulses only at the moment of rising with 880Hz. |
