| 摘要 |
<p>PURPOSE:To achieve muting for a sufficient time including the time when a circuit is stabilized by alternating recording and reproduction according to the sum of the time from the closure of a trigger switch to the muting of a detection switch and the time until the flip-flop circuit is reset. CONSTITUTION:With a recording button pushed, a switch 6 is closed in a short time to turn on a control transistor (TR) 20, and the output of the 1st comparing circuit 9 makes the output of a flip-flop circuit 8 go down to a level L to turn on a TR14, thereby starting muting operation. At the same time, a TR16 turns off to start the charging of a capacitor 18. Then, a detection switch 19 is short- circuited to charge the capacitor 18 to the earth potential, and the switch 19 is reset to start the charging of the capacitor 18 again. Then when the 2nd comparing circuit 10 generates an output H, a signal is applied to the reset terminal of the flip-flop circuit 8 to turn off the TR14, resetting the muting state.</p> |
