Need some electronics help.

[rhubarb505]

I realise that this has little to do with dreamcast's but this is the only forum I know where there are some people who really know their stuff.

Im building (sort of) a clock. I'm using the timer from an old one that took apart. I was planning on using using my own LEDs and making my own display, but the voltage would be much too low if I just ran some LEDs off of the inputs that go into the tiny display for the old clock.

I need something that will allow me to, when current flows through it, to turn on a secondary power source (say an adapter plugged into a wall). This will allow me to use the current from the inputs from the timer to turn on a different power source to power the LEDs.

Does such a device exist?

[ninja]

Relay's my friend, Relay's

[rhubarb505]

I wikipedia'd relay and it looks to be exactly what I needed. Thanks!

[Roofus]

You guys should also look up "apostrophe."

[rhubarb505]

touche

[semicolo]

relays seem a bit too much just to power leds, use standard transistors/resistors (2n3904 should be ok, since i used them to power 8 high intensity leds)

something like this should do the trick (you may need to adapt resistors):

[semicolo]

well 4700 ohms is probably too much, if you use a 5V vcc and want 10mA flowing through the led, use 470 ohms.

[rhubarb505]

That does seem a bit more practical...