Has anyone ever built one?
Basically, it's an LED indicator that let's you know when your battery drops below a certain voltage. I'd love to build one for my active bass. Here's an example of a commercial one, but it's $40... gotta be easier to make one yourself: http://www.bestbassgear.com/john-east-bli-01-led.htm
Boss pedals have a zener diode in the LED path. The LED dims before the pedal is affected by the dying battery - so you know to change the battery before your audio is compromised.
Andrew.
Interesting...
There's no LED on my internal bass preamp, but maybe there's a way to adapt that zener technology to add an LED that would only light up when the battery is dying?
That zener method.
http://www.dazatronyx.com/tech/low-battery-led-fading/
I would think the resistor value would need to be adjusted for your particular LED.
Just found this... it's something. Gotta learn vero!
http://www.paulinthelab.com/2012/11/low-battery-indicator-9v-stripboard.html