Indicator
Power-On Indicator and Battery Monitor for Active Basses & Guitars
JTEX Indicator solves two common problems with active basses and guitars:
It continuously indicates that the instument is on by flashing green for as long as the instrument is powered and the battery is good (>7V). The flashing will catch your eye, reminding you to unplug the cord when you're done playing, to keep the battery from draining.
It notifies you that the battery is running low by turning a steady red when the voltage drops down to 7V. This is before your tone starts suffering and long before you risk a sudden power loss on stage. Just remember to replace the battery soon.
The Indicator's own current draw is negligible (30 microamps while flashing), so it won't reduce battery life. It is designed for 9V power, but an 18V version can also be made, with a low battery warning at 14V.