4-Channel Selector Stereo Audio Circuit Diagram

This is the 4-Channel Selector Stereo Audio Circuit Diagram. This scheme is used for connecting stereo outputs to four different channels of inputs and only one selected for output at any time.



4-Channel Selector Stereo Audio Circuit Diagram

When choosing the circuit breaker per channel (AR and AL). If there is no audio on channel A, waits scheme for some time, and then select the next channel (channel B) .The search continues until until it detects a sound in one chenal.The delay between channels or wait can be adjusted using preset VR1. If time is no longer necessary, you can replace the capacitor C1 with a higher value.

Jump manually from one channel to another channel active active, simply press the jump switch (S1) to the correct input channel is selected. The selected channel (A, B, C or D), denoted by the corresponding bright LEDs (LED 11, 12, 13 or 14).

IC contains 4 analog switches CD4066, these switches are connected to four channels. These analog switches controlled by IC CD4017 outputs. CD4017 10-bit ring counter IC. Since only one of its products is high at any time, only one switch closed at a time. CD4017 IC is designed as a ring counter 4-bit by connecting the fifth output Q4 (pin 10) on the reset pin. Capacitor C5, in connection with the resistor R6 form a power-on-reset IC2, so that the initial change in the power supply, the output Q0 (pin 3) is always ensured high. The signal IC1 CD4017 NE555, which operates as an astable multivibrator when the transistor T1 is in state court.

KA2281 IC5 is not only used to indicate levels of stereo audio channels selected, but also bias the transistor T1. Once a particular sound detection threshold in the selected channel, the pin 7 and / or 10 pin IC5 goes low. This low level is coupled to the base of transistor T1 through a combination of diodes D2-R1 / D3-R22 resistor. As a result, the transistor T1 conducts and causes the output of IC1, in order to remain low until the output signal level of the selected audio channel exceeds the threshold.

VR3 VR2 and Presets are included for adjusting each of the threshold levels for audio left and right stereo channels as desired. Once the action multivibrator IC1 is disabled, the output of IC2 is not changed more. Therefore, searching through the channels continues until it receives an audio signal above the threshold. Jumping the switch S1 is used to jump from one audio channel, even if present in the selected channel. The number of channels can easily be extended to ten by 4066 the use of additional integrated circuits.