Active Electronics Led Indicator

[GGW]

I ran across a circuit that looks like a good idea. It's a LED that lets you know when your battery is loosing power to your active pickup system.

LoBat

I've checked around and can't find an equivalent DIY circuit. Shouldn't this be fairly a simple design of dropping the voltage across a resister to just above the trigger voltage? I'm not sure what the intregrated circuit is doing there and why they claim their circuit uses so much less power; they still have to light the LED, right?

[mammoth guitars]

I'm not sure what the intregrated circuit is doing there and why they claim their circuit uses so much less power; they still have to light the LED, right?

It does not use much power until it needs to turn on the LED at which point the LED drain does not matter since its an indicator of a low battery.

[psw]

I have built a circuit like this, the op-amp is important but is a fairly simple and cheap device and will indeed draw very low power. They have made it with SMD parts so it is very small, but you can get the same thing in a kit form from various places down here Low Battery Indicator Kit This one uses a dual color LED so the color will change when low and serve to show power is on as well!!! A$8.95 is pretty cheap, couldn't see what the LoBat goes for.

[lovekraft]

Here's a simple one using an LTC1440, uses about 4uA in standby:

http://www.discovercircuits.com/DJ-Circuits/9vbatmon1.htm

Here's a really flea-powered example, from EDN:

http://www.edn.com/article/CA318716.html

HTH

[GGW]

Thanks everyone. I wasn't understanding how the circuit worked. I was thinking it was more of a power on indicator. That seems to be more the way I'd want it to work. I just find it a bit strange to have a light on your guitar that is always off. The circuit from PSW looks good and thanks lovecraft; I'll look into building one of these as well.