ADD - ON STEREO CHANNEL SELECTOR by PRABHASH K.P.

The add-on to the circuit presented here is useful for stereo systems.
This Circuit provided for connection Stereo outputs from four different
Sources / channels as inputs and a single chosen by them is / are connected
Exit at any time.

When power is turned "on" Channel A (A1 and A2) is selected. If not,
The audio is on Channel A, the circuit waiting for some time and then
the next channel (channel B), The The search operation continues until it is detected
The audio signal on a channel. The other channels have to wait or delay
The time can be set by Preset VR1. If the time longer
necessary, you can replace C1 Capacitor with a higher value.

Suppose that is, Channel A-line is connected to a tape recorder and the channel B
a radio receiver. The first time A channel is selected, the audio
the tape recorder be present Edition. After the tape is played entirely
or if you have enough rest between successive shots, the circuit automatically launch
radio receiver. To manually from a jump (selection) active channel, press the jump
switch (S1) at the time, one or more times until the desired input channel
selected. The selected channel (A, B, C, or D) is indicated by a light
LED (LED 11, LED 12, LED13 and LED14, respectively).

Analog IC CD4066 contains four switch. These switches are four separate channels. For stereo operation, two similar chips CD4066 as shown in the circuit. These analog
The switches are controlled by IC CD4017 outputs. CD4017 is a 10-bit ring
IC against. Since only one of its outputs high all the time, only a
Switch is closed at a time. IC CD4017 is a ring of 4-bit configuration
Connecting the fifth counter output Q4 (pin 10) on the reset pin. Capacitor
C5, in conjunction with R6 forms a power-on reset circuit for IC2, so that
the first step "in the" power Supply, output Q0 (pin 3) is always 'Strong'. The watch is expected CD4017 IC1 (NE555), which acts as a astable multivibrator when transistor
T1 is in state court.

IC5 (KA2281) is not used here just to point out that the audio level
selected channel stereo, but also transfer Polarization of the transistor T1. Only
a certain threshold of audio detected in a selected channel, the pin 7 and /
or pin 10 of IC5 goes "low." This low Level is the base of the transistor, along
T1 with diode-resistor combination of D2-R1/D3-R22. As a result, the transistor
T1 conducts and the cause of the output IC1 to remain "low" (off), if
selected channel's output exceeds audio threshold setting.

Preset VR2 VR3 were recorded and Set individual audio- The thresholds of the left stereo channels, if desired. Once the multivibrator Effect of IC1 is disabled, the output of IC2 does not change. Therefore, research through the channels until receives an audio signal and "higher preset threshold. The jump S1 is also used to move a channel when the selected sound in the channel. The number of channels can extended to ten, the use of new 4.066 chips.