How to drive several LEDs

[CraigC]

I am building a project that requires LEDs to light a faceplate for several seconds. That is all figured out. Problem is the on paper, the output of a monostable vibrator drives 4 to 6 LEDs. Is there a pull up/ down resistor array or something else I can use to reliably drive the LEDs? Thanks. Drawings always help.

 

[Jaw174]

well, i would use the singla output to trigger a transistor, whouch would allow current to flow into an array of leds, wired in parallel with individual series resistors.
ill just assume your going to use somewhere between 5 and 12 volts for this..

the value of the resistors is depentant on the led and the voltage... if its 5 V , itl be between 100- 250 Ohm leds, for 12V itl be between 180 and 330 ohm resistors... i ususaly just guess, but if you use Ohms law, and u know how much amperage the leds drop in normal operation, you can find the exact resistance for the leds

then, depending on the leds used and how manny will determin what type of transistor you can use... if you use ALOT, then you must use a higher wattage rated resistor, if you are oly using a few, then a lower... for the higher i would use a 2n3055. for the lower you might be able to use a 2n3904

here is a small schematic of the circuit