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Standby LEDs Answered

I got this idea from a flashlight we happened to get in at work. When the flashlight was in the off position there was a little dim red light by the power button indicating that it was off I guess but when turned on the red light turned off. I tried to find this flashlight again so I could rip it apart and figure out exactly how it does it. Anyways, my first thoughts were capacitor but as I thought about it I don't think this is true because this thing can stay lit forever. I'm guessing that it is somehow hooked up to the batteries through a resistor but I'm not understanding how it lights up when its off but turns off when its on. Maybe switch related? Anyways, I've only been messing with electronics for about a week. If someone could shed some light it would be most appreciated. 


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7 years ago

It uses a simple 2 position switch. When in one position it allows the power to go to the main LED of the flashlight. When in the other position it turns on the power to the indicator LED. Nice option if you have to search for the flashlight in the dark but not so nice for keeping good batteries in the light.

See attached schematic.