I am making a voice recording and playback device based on the ISD4004 voice chip. I don’t know where it is except the problem. The sound is always loud during playback and the playback sound of the recording is very small. Could you please tell me what is wrong with my circuit?
Jenna Posted on August 20, 2020
It is wrong to take VCC to supply power for mic, and it must take a regulated power supply.
Mason Posted on August 20, 2020
Is it necessary to add a voltage regulator to VCC?
Poppy Posted on August 20, 2020
1. LM386 refers to the peripheral circuits in the manual as much as possible, and the phase compensation circuit of the audio output is best to be supplemented to avoid the noise caused by self-excitation;
2. The capacitance value of C13 can be increased to 4.7uF;
3. The power supply of audio IC U3 and U4 should pay attention to the ripple quality. It is best to use a linear voltage regulator to stabilize a power supply separately. At the same time, the VCC pin accessory is connected in parallel with a 103 or 104 filter capacitor.
4. R3 and R4 can be increased to 10K (as far as possible in accordance with the reference circuit of the IC data)
