PURPOSE:To avoid malfunction by a short signal such as noise, by using a time constant circuit so that FF circuits can not be inverted when no signals are received within a specified time or more. CONSTITUTION:When a reproducing signal (a) is absent and non-recording is made, a DC signal is lost, a transistor 10 turns on, and the state of a tape recorder is switched from a normal reproducing state into a stop state or from high speed reproduction into the normal one. When a positive pulse signal is absent, a transistor (TR) 13 turns on. If a signal such as noise is recorded only for a short time at non-recording, the TR13 is kept short-circuit. Thus, when a short reproducing signal b is lost, even if a signal is generated in a non-recording signal generating circuit 4, operation is made that no pulse signal is applied to a control circuit 8. Thus, malfunction due to a short signal such as noise can be avoided.
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