Author Options:

I tried to create a 2 led driver from the mains. Can you please check it? Answered

(This is just an experiment)

The first circuit failed due to my mistake of using polarized caps. I replaced it with non polarized now.
Can you please check if it would work? I don't want a loud explosion again :)

Capacitors: 0.47uF 250V
LED: 3V White
Diode: 1N4004



Best Answer 6 years ago

Those capacitors  Must be rated 200V or more each preferably 400V
The diodes are wired correctly,
the equivalent series capacitor is 235 nF
capacitive reactance is Xc = 1 / 2*Pi*F*C = 109 / ( 2*3.142*60*235 ) = 11.2K
Peak LED current = VAC*1.414  /  Xc = 230*1.414 / 11200 =  o.029 amps.

This current is a bit higher then 20 ma but it flows for only a peak moment
and only a half cycle at a time.

Put a o.1A fuse in series with the capacitors.

AndyGadget and Re-design both offer good safety advice !
You are only 18.........  Do you know how to work
with one hand in your pocket when the power is ON ??

If one of your caps is miss-marked or there is a surge in the line,
your nice face could be scared for dating ;-(
This is only for an experienced technician.

Take great one handed care !!!


Thank you for checking this circuit.

Btw "Do you know how to work
with one hand in your pocket when the power is ON ??"

What does this phrase mean? Is this literal? :)
Sorry for that.

Thanks for the best answer.
If you literally have one hand in your pocket,  you cannot place your hands
across the mains power by a thoughtless accidental move and
draw Lethal current across your chest cavity going through your heart
thereby possibly extinguishing your life.
Whatever work takes two or more hands. First, one hand turns-off,
unplugs, disconnects a clip cord  to the dangerous power. 
Then use all your hands to make the the changes :-)

Yes, one can still get a shock across the fingers, it may even burn off
your a finger or two but you will live.......   to regret it :-)

"First, one hand turns-off,
unplugs, disconnects a clip cord"

don't worry i always do that.
i know the dangers of mains.
i will be very cautious.

This is very dangerous - It is possible to drive LEDs this way but there are so many things to go wrong - possibly fatally -  it's not worth the risk.

Get yourself a wall-wart and experiment with the output from that.

i first test it using a 9v transformer. its not a dangerous voltage, right?

You'll be perfectly safe with 9V.  Connect your 2 LEDs across it with a 220R resistor in series and your LEDs will light (as long as the LEDs are connected the right way around).
HERE is a LED tutorial to get you started - There's many more if you google for them.

I agree. There is no way I would try this without working on the safe end of a transformer.

Caps have a nasty habit of shorting when they fail and this would be very dangerous.