555 continuous recording keeping sound control circuit

Published:2011/6/16 1:47:00 Author:TaoXi | Keyword: 555, continuous recording, keeping, sound control | From:SeekIC

As the figure 14-9 shows, the sound control circuit uses the 555 as the core, the monostable delay circuit is composed of the 555 and R2, C3. The recording signal gets into the circuit from port A, when there is no signal, VT1 cuts off, pin-6 has the high electrical level to reset 555, pin-3 outputs the low electrical level, VT2 cuts off, the motor M stops working, the circuit will not tape. When port A has the signal, the signal is amplified and rectified by D1, D2 and C2, the VT1 conducts, pin-2 has the low electrical level, 555 sets, VT2 conducts, the motor M starts working, the circuit will start taping. When there is no recording signal in a short time, the 555 will not reverse immediately, only when the C3 is charged to the 2/3VDD of pin-6 through R2, the 555 resets, pin-3 has the low electrical level, the delay time td=1.1R2C3, it is about 5 seconds.



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