Fat General / LED question

[ryugu]

I got my FG built up and when I first plugged it in, I noticed that only one green LED lit up. I was surprised b/c I put extra special care into building this one. It sounds very good though and I can easily hear the compression. Are the LEDs supposed to flicker on and off with the input signal? Any idea why only one LED lit up?

I should add that I only did a quick test drive with it outside of its case

 

[Cybercow]

From what I can make of the circuit, and your expressed experience, I'd say it's performing as it should. Only one LED lights up at the start is likely just the initialization voltages. Once the circuit gets a signal, the LEDs should flicker a bit, each of the two LDR/LED pairs each manipulating the upper (positive) & lower (negative) swings of the signal.

What is the state of the LEDs after a signal stops while the circuit is powered?

 

[Alan W]

And you really need it in a case to test it (aurally)—the circuit relies on a photo-resistor that is reacting to the LED that is mounted right next to it, so it needs darkness to have a sense of how much signal there is.

Take close up shots of the board, from both sides if possible, and post them. That will help people see if there’s a cold solder joint, etc.

 

[ryugu]

Thanks for this input. I'll give it another try.

 

[Alan W]

Thanks for this input. I'll give it another try.

Try it in the open, but in as dark a room as possible. Chunk some chords, and watch the LEDs.