Me and my dad, made a fitted cuoboard a while ago. I wanted to put hyper bright leds inside the cupboard, so i can see a bit better . Its a corner cupboard. I wanted to connect the leds to a light switch (mains). I know that leds can work of 12v with the use of the right resistor. So i thought i can make the leds work in the same way of the 12v spot lights you get for your house. So i bought a step down transducer ( i think thats what it is called, cant remember), from 230v to 12v, (the ones you use for spotlights) then that would normaly connect to the series of 12v down spot lights, but i though i can connect it to the resistors then leds. BUT.... Leds work on DC, and some were i read the tranducer uses AC, but am not sure. Can some one clear this for me. DO down spot lights use AC or DC?? I thought i can use a simple adapter, but i use so many power points already, so i am just tring to cut it down, and make my room a bit more better. Thanks for reading.
Getting stabilised DC out of a switching supply or transformer is an extra step with extra components, so that is skipped for powering lightbulbs since they work off AC just as well. You can get DC with a rectifier bridge and a capacitor to stablise. But remember that you might not get exactly 12V, and allso you may need a minimum load on the switching adapter to get a stabile output. The minimum and maximum load is usualy marked clearly on the supply.
ok actually since an led is a diode it doesnt NEED a rectifier bridge to work and since most electricity is 50 or 60 hz u dont need a capacitor to filter the wave because its faster than your eye anyway. all you need to do is calculate the resistor you need. do this be taking the rated mains volts and multiply by the square root of 2 or 1.4 to find the peak voltage. subtract the rated led voltage from this and then divide by the rated current on the led. just put the resistor and led in series. i have successfully done this in the US but i have not used the led for any extended amount of time so you might want to check up on this or wait for someone to correct me. i have seen people put another diode in parallel with the led but reversed polarity so the ac can flow both ways this should help the life span of the led. hope this helps
Some people get headaches or discomfort from lights that flicker at 50-60Hz, and they allso look strange if you move fast (strobe lights anyone?)
Why not wire half 1 way and the other half the other way so that you have light on which ever way the current is flowing. The light would then be flickering at 100-120Hz which isn't so bad. Heck, why not even build a bridge rectifyer out of LEDs?
