Dying battery indicator

[jeff]

 Hi I don't really use pedals much, but when I did I seem to remember as the battery died the led would light faintly when the battery was going to let you know it's time to replace it.

 I understand using a 3PDT  to light an led when the pedal is on and make it go off when the pedal is off but how do you make the led go on when the battery is dying?

Schematic would be helpful.

Thanks
 Jeff

[HotBluePlates]

As the battery is dying, you want a light (eating the battery) to tell you it's dying? That doesn't seem to make sense.

If you just unplug your guitar from the input jack, it'll usually switch the battery off so it doesn't die. At least, that's how most pedals are set up.

[jeff]

As the battery is dying, you want a light (eating the battery) to tell you it's dying? That doesn't seem to make sense.

Yeah, Some indicator of how fresh your battery is without having to take it out and measure it with a volt meter. That way you'll know if you can make it through the show and prevent the need for putting in a new battery before you need to, just to be on the safe side.

 I haven't used a pedal in a while but I thought when you had a fresh battery, the LED would light when the effect was on and when it was off the LED would go out.  But as the battery died, when the effect was off the LED would light faintly to tell you it was time for a new battery.

 Not a seperate LED but the effect on/off LED. Maybe I'm remembering it wrong(once I started messin' with tubes I gave away all my pedals)

[sluckey]

My MS wireless mouse 5000 has a low battery indicator light. It will pulse slowly whenever the battery gets below some threshold voltage.

You could build a threshold detector using a comparator chip. Google it.

Or, you could do the reverse. Have a LED lit up as long as the voltage is 'above' a certain threshold by using a zener in series with the LED. Much easier. For example, 9 volt battery, 2 volt LED, 5 volt zener, current limiter resistor. If the battery drops below 7 volts, the LED should go dark.

[Ed_Chambley]

Yea, I know what you mean.  I have some old pedals with no light or the ability to use a power supply.  All of my amps have an extra AC socket for plugging in a power supply and 3 of my amps have them built in.  On some of my older pedals I have used a 9v battery snap and connect them to the one in the pedal then this is soldered to a plug to fit the power supply so I don't have to modify them.  Some of them bring stupid prices.

Anyway, it doesn't take long for the cost of batteries to exceed the cost of a power supply.  Players have been using pedals for a long time and a pedal does not change a tube amp into SS.  We can get amps to have overdrive and distortion, nice reverb and tremolo.  It is those darn things like delay, chorus, treble boosters, phaser, etc...............that makes it so I cannot just plug into the amp.