How can I turn on a LED light with samll DC current?

Question

I have 5 mA DC current with 0.9 volt from a galvanic metal circuit. I want to turned on a LED light using this current. Is it possible? If possble, I do not want to use a battery.

Answer 1

You need to use a "Joule Thief" circuit which is basically a blocking oscillator which bumps up the voltage to drive the LED. Two of your galvanic cells in series would be better but a Joule Thief can be made to work at 1.0V, perhaps just maybe 0.9V. There a couple of examples in the links below.

Answer 2

You need about 1.5V for lighting up an LED. It is like a wall 15 feet height. If one cannot get across it, you cannot LIGHT up. Presently your "height" is 9 feet, since voltage is 0.9V. see if you can make two of these, and connect them in series. In that manner you can get 1.8V at 5 mA. Then you can light up the LED.

Answer 3

sure.. just get a super low voltage LED