# 5mm 6 no of led for night lamp to plug in 230v 50hz power supply ?

i want to make 5mm 6no. led night lamp can directly plug in 230 v ac household power supply ? is it possible ..

i want to make 5mm 6no. led night lamp can directly plug in 230 v ac household power supply ? is it possible ..

I am thinking this night light thing of yours could be implemented using a capacitor in series with the LEDs, and maybe a small resistor also, although I would rely on the capacitor's impedance to 50 Hz AC to do

mostof the current limiting.The formula for this impedance is, X = 1/(j*2*pi*f*C). So, for example, a 0.1 uF capacitor, at 50 Hz, has an impedance of about 3.18e4 = 31800 = 31.8 K ohms.

The really neat trick to this is the capacitor is not dissipating any real power. In contrast a resistor of the same size would dissipate I^2*R. For example at 10 mA of current that would be I^2*R = (10e-3 A)^2*(31800 ohm) = 3.18 watts.

Regarding the capacitor, you kind of have to pick one that can actually withstand having around 230 V AC across it. An electrolytic, or any polarized type, capacitor will NOT work for this, since those kind of capacitors actually require the mean voltage across them to be DC.

Anyway, if you let me know how many (6?) LEDs, and what color they are, I will try to come up with a circuit diagram for this.

I'm also a fan of THIS wizard for LED arrays because it does the parallel/series calculation for you. Not a huge deal with such a small array but if you ever do something bigger or with an odd number it can save some trial and error on picking the number of strings.

Also note that these calculations we've posted are making an assumption about the forward voltage of your LEDs (one calculator used 3.6 V for white and the other 3.3) and output voltage of the transformer. You will need to rerun the calculations when you've picked out components.

The only safe way is to isolate the LEDs from the mains with a small transformer - Either the 'wall wart' type which plugs directly into the wall or an in-line one. You've probably got at least one spare around the house. A 9V or similar one would be ideal. The current doesn't matter as you'll be drawing very little.

For a 9V transformer I'd wire 3 strings of 2 LEDs across the leads, each string with an 82 ohm resistor in series. I got that figure from the calculator HERE. I'm assuming white LEDs and a current of 20mA. Use a higher value resistor if you want the LEDs dimmer.