I'm sorry I know I already asked for the similar question but now I learned how to properly ask my question and I will detail it more on this thread.
I have a DIY mixer on breadboard right now.
It's only 1 channel for the moment and I used a SPDT switch to pass the signal on or off. The center pin of the SPDT is connected to the output. Left pin is at the input where the signal comes from, and the third pin is on ground to minimise the noise when the switch is on the muted status.
I successfully added an LED with a 3904 transistor on this channel so when the SPDT is on, passing the signal to the output, this audio signal (AC I guess) is turning the 3904 transistor on and lets the green light monitors the signal, this LED reacts to the audio signal, like a level meter LED bar graph but only 1 LED, it flickers as the sound frequencies are being played.
Now my question is I want to add another LED, a red one, that would turn on ONLY when the SPDT switch is turned off (this is the muted state for the chanel mixer.)
I tried many things already, with 3906 or other simple circuits I found online for toggling 2 leds but since all I find online is using a steady voltage instead of an audio signal like I do right now, it makes my circuit light up both leds when the signal is on.
So I guess either I would have to block some portion of the audio signal triggering both LEDs (which should trigger just the green ON LED) or convert the audio signal to a DC voltage like something 3V for on and 0V for off. If I can know how to convert this audio signal to 0V or 3V it would solve my problem because right now K can turn on the muted red LED when the audio signal is muted but I can't make it so that when the spdt switch is on it only light up the green led, not the red led.
I hope it is more clear now, I'm sure this is basic electronics but 'm new to all this so it's complicated for me.