hi at moment trying to light a dolls house have an abundance of 3mm 2/3v 20ma warm white leds am thinking of using 20 or so was hoping to use batteries so far have about 8 in at moment wired in parallel using 2 aa batteries and very dim like me! think am missing something do i need more power or?

 

Do you have current-limiting resistors for each LED? Are they pre-wired with resistors?

Pictures would be lhelpful along with a link to the LEDs.

 

sorry no link just chinese leds they are 3mm warm white polarity long lead (+) V(f) 3v - 3.2 1 (f) :20ma all i know sry. Dont have any resistors i think! just wired 8 up in parallel with 2 aa batteries and they are lit but dim.

 

From my experience with led lights for doll houses, they don't have any series resistors as they run on 3V batteries and rely on the internal resistance of the batteries. I rewired them with a 150 ohms resistor and run them on 5V phone charger they work perfectly fine.

 

I would use them wired as 4S powered by a 12V supply into a jack. Batteries won't last long. 5mm LEDs are more efficient and Vf ~ 3.1 and if ultrabright will be adequate and not have thermal runaway at lower Vf=12V

 

You said the ad for the LEDs say the max forward voltage is 3.2V. Then some of them will be dim when powered by 2 brand new AA alkaline batteries and even dimmer if the batteries are cheap (super-heavy-duty) or are old.

 

Thanks gentlemen will go with Dodgydave see how things go

 

Thanks gentlemen will go with Dodgydave see how things go

Put a resistor in series with each led, then put them all in parallel across the 5V supply.