drive many leds from a single dout pin

[polosid]

what can i use to drive groups of 16 or more leds from a single dout pin?

i don't want to use relays with mechanical parts. is there an alternative?

[Max Romantschuk]

I don't know about the exact details, but a technique called multiplexing can be used to drive more than one led from a smalled amount of pins. Try searching for "led multiplex" or "led rings" for some pointers in the right direction. Use the advanced search and check "Show results as messages" for more easily read results.

You do mean driving more than one led so that some can be on and some off, right?

In any case, relays shouldn't be needed regardless of the technique. A plain old solid state transistor can be used to switch a circuit on or off, relays are only needed when switching an independent circuit (say mains or something) on or off by a control voltage from another circuit.

[polosid]

no no... i don't need to control each led individually.

the leds are connected all together in a cluster...

[SLP]

see http://www.midibox.org/forum/index.php/topic,11642.0.html

especially:

use the uln2803 8 darlingtons in 1 handy pkg...