LED driver.

i want to make a LED light source, I have found a few on other places, but not sure of those.

I have a 9v battery, 4LEDS.  If anyone would be so kind, I have two set ups I am considering.

One will have a 555timer, to make the LEDS "pulse"   

The other is just direct connect battery to LED i am aware a resisitor or several are needed for this direct arrainagement, so my question for this setup is how to make the most of it.

a third option is to incorporate the two above. 

*did find an instructable which used a wall plug as the driver, with some modification of course.
thanks in advance.

kadris36 years ago
many white leds are 3.4 vdc. you will be happier with a 4.5 power supply as 9 v batts tend to get expensive. here goes both ways.
9 vdc batt will do 2 white leds in series with a 110 ohm resistor(series to limit current)
a 4.5 vdc supply requires a 55 ohm resistor in series with each led. more can be paralleled up for more light. good luck. unclecutheledguy.
ganglion7 years ago
The thing is to work out what the voltage drop of your LEDs is. Some multimeters let you measure this, or you might be able to find it in the specs. Usually it's between 1.5 and 4 volts depending on the colour. Once you know this (and also the maximum current they are designed to handle), you'll be in a better position to work out how to drive them properly. Your best bet is probably to go back to the website you ordered the LEDs through (if you bought them recently) and see if there's a spec sheet for that product. Hope this helps.
mossDboss (author)  ganglion7 years ago
thanks for your input. i should be getting the LEDS tomorrow and should be able to find the info needed. will update when I have the info