230v mains powered Led

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rahnette

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230v led circuit

Hi,

Has anyone any suggestions for a simple circuit to power an LED from 230v 50Hz Mains voltage (UK).

grateful thanks for any response

rahnette
 

mains led

Use capacitor as resistor Rc=1/ωC.

for 10mA use 150nF, for 20mA use 300nF.


Regards.

Mr.Cube
 
mains powered led

Thanks mrcube_ns

But could you explain calculation in simpler terms my maths is a bit rusty;-)

I presume you mean to place capactor in series with LED?

regards
rahnette

Sorry if i'm asking twice but went to post reply before your attached file loaded in my browser.
 

led mains indicator

You will need to connect another silicond diode (1N4004 or similar) to protect LED against reversed polarity.

If you assume that he LED current will be 10mA then to drop 220V you need approximately 22000Ω.
As suggested by mrcube_ns you can use a capacitor (no heat) instead of a resistor.
So here are data necessary to performe calculations:

Rc(for 10mA @220V) = 22000Ω
ω=2 *Π * f
f=50Hz

C = 1/ωRc=1/2*Π*50*22000=144nF closesed available capacitor 150nF/400V...
 

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    rahnette

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led 230v circuit

Help is much appreciated.

I was a bit mystified by the symbol ω in the equation, it has been a long, long time since I used this kind of maths.

However I am still a little confused. I know that LED's are current driven devices but what will the forward voltage be? and what type of capacitor would be needed?

rahnette
 

230v led driver circuit

I am using 100kohm connecting series with LED and the circuit work fine
 

led from mains

I know that LED's are current driven devices but what will the forward voltage be? and what type of capacitor would be needed?
Click to expand...

1. you need a non polarisated capacitor
2. if you put the 1N4004 diode in antiparalel with the led, the maximum reverse voltage will be 0.7V

hope this help,
//a
 

mains leds

CAPACITOR: Good choice will be Class'X2' or Class 'Y' 250Vac Metallised Paper capacitors which are available, for example, from RS Components.

Other thing to do would be to check the current of the LED. For most standard LEDs the If(max) is somewhere around 25-30mA but there are some low consumption LEDs which work with currents below 3mA.
 

mains led indicator

Either the resistor or cap in series with the LED will work. The resistor will be cheaper, but will run hot. I would use a 1n4007 diode accross the LED (opposite polarity to LED). The 1n4007 has a higher voltage rating than the 1n4004 and is about the same price.
Use hi-brite or ultra-hi-brite LED, because a lower current is needed. 10 mA will be more than enough. The forward voltage of an LED is typically 2V depending on the color, but at 230V supply, this is irrelavant.
As mentioned above, use a 150N cap or 22K resistor (5W). You could probably get away with a 47K resistor or 68N cap if you use an ultra-hi-brite LED. Remember the cap's voltage ratings are usually DC, unless specified. Use 250V AC or 600V DC rating.
 

led powered by mains

haha - whoops i think i severely misread the question. 4001 in parallel with the LED, 100k in series with the lot. yup that will work fine, i guess i had interpreted it as 4001 in parallel with R+D which would not work.

hey a note i think should be in here though is that the power dissipation of that 100k will be 144mW, not the right region for a little 1/8 W resistor. use a bigger wattage, or put 5x500k (1/8W) in parallel so you don't smoke them.
 

led 220v circuit

I thank you all for your interest

Reason for question:

Have large Cooler unit in Potato store with many neon indicators these have had to be replaced many times due to failure or dimming over time. Would like to replace with LED indicators but these are relatively expensive. Since I already have a stock of LED's, diodes ect. I thought it would be nice to build a remote display unit which I could place next to the controller which is more accessable than the cooler unit itself.

I am now armed with ample info and will get experimenting.

rahnette
 

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