BA5104/BA8206 audio remote control circuit diagram

It would be great if you could design a remote control circuit for the audio system . Haha today we are using Tesco’s fan IC BA5104/BA8206 as the control chip. Through reasonable design, we can maximize the function of the chip. It has worked very well after using it, and I would like to introduce it to everyone. It can achieve the following functions:

　　①Manual control/remote control;

　　②Volume remote control;

　　③Sound source selection;

　　④ Delayed shutdown;

　　⑤Speaker protection when switching on and off;

　　⑥ Sound and light display.

The principle of the transmitting circuit is shown in Figure 1.

The receiving and main control circuit principles are shown in Figure 2. IC2 is the fan circuit chip. This article introduces its working principle as follows.

1. Manual control/remote control: Press the remote control button in Figure 1 to realize manual control/remote control, which is convenient to use.

2. Sound source selection: Press the on/select button, IC2 pin 13 first outputs low level, causing the red LED6 to light up to indicate that the power is on, and V4 is turned on, K1 is powered on, and the power amplifier is turned on. After 3 seconds, pin 13 returns to high level, and pin 14 turns to low level, causing green LED7 to light up to indicate that audio source 1 is connected. V5 is turned on, causing K2 and K3 to be powered on, and the connection is shown in Figure 2. Source 1 signal and power in (a). Due to the action of VD2, V4 is still conductive, causing K1 to pull in and turn on the power amplifier. At the same time, K4 is powered through VD8 to turn on the speaker.

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If you want to use audio source 2, you need to press the on/select button again. Pin 14 of IC2 returns to high level and pin 12 is low level. Blue LED5 lights up to display audio source 2, and turns on V3. K5 is powered to connect the power of audio source 2, and then K4 is connected through VD9 to connect the speaker. At this time, K2 releases the signal to turn on the sound source 2, and K3 releases the signal to turn off the power of the sound source 1.

If you want to mute, just press the on/select button to keep the red LED6 on.

Because BA8206 has a memory function, it will automatically restore the working state before the last shutdown the next time it is turned on. If you were listening to audio source 2 before shutting down, the next time you turn on the phone, pin 13 will be at low level first, and after 3 seconds, pin 12 will be at low level to connect to audio source 2. It is convenient to use without having to re-select the audio source every time you turn on the phone. .

3. Volume remote control: The 20th and 11th pins of IC2 in Figure 2b are two independent bistable output terminals. When adjusting the volume, if you press the volume + button, the 20th pin of IC2 outputs a low level, causing V8 and VD3 to cut off, and LED8 Lights up for display and makes V6 conductive. The power supply V+ passes through V6, volume motor M and V9 to the power supply V- to achieve volume increase. If the volume - button is pressed, the 11th pin of IC2 is low level, causing V9 and VD4 to cut off, LED9 lights up for display, and V7 is turned on. Power supply V+ goes to power supply V- via V7, volume motor and V8. Reverse the motor to reduce the volume.

Adjust the volume above to the appropriate level. You need to press the volume + or - button again to restore pin 20 or 11 to high level. Normally, V8, V9, VD3, and VD4 are all on. Because V6 and V7 are cut off, the volume motor stops rotating because there is no current flowing through it.

4. Delayed shutdown: Press the timing button after turning on the computer to make the delayed shutdown time accumulate from 0.5-7.5 hours, and LED1~LED4 will display accordingly. During the delay process, LED1~LED4 will display corresponding decrements, and all will go out at the end, which is very intuitive. This feature is great for night use.

5. On/off airport speaker protection: Each time the power is turned on, IC2 pin 13 first outputs a low level to turn on the power amplifier, and then turns on the selected audio source 1 or 2 after 3 seconds, and makes K4 pull in to turn on the speaker to avoid This eliminates the current impact on the speaker when it is turned on. When the power is turned off, pins 12, 13, and 14 are at high level at the same time, but due to the action of VD1 or VD2, C2 is charged to a low level, so that V4 is still turned on and the power amplifier is turned on. At this time, audio source 1 or 2 and the speaker has been disconnected, which also avoids the current impact on the speaker when shutting down. According to the capacitance of C2 in the figure, it takes 3 seconds for V4 to cut off and turn off the power amplifier.

Protection circuit: After the voltage is divided by R1, R2 and R3 from the midpoint of the power amplifier output, no matter when the positive or negative bias of the midpoint of the power amplifier reaches 2V, V1 or V2 will be turned on, and the ③ pin of IC2 will be connected to the ground to achieve shutdown protection. .

6. Sound and light display: Various control functions in the picture have corresponding LED displays. Already introduced above. At the same time, HTD will chirp once, which is very intuitive.

IC 1 in Figure 2b is an infrared receiver, and the LED in Figure 1 is used as a button for remote control transmission display. 3mm high-brightness light-emitting tubes are selected for LEDs of various colors.
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