Running LEDs from mains power

[samuel2801]

Hi i am building a sculpture at uni and i need to power some LEDs. Once the sculpture is finished i wont be able to access inside to change batteries. Im looking to power around 4 to 8 5v LEDs from a 240v plug and wanted to know what is the best (and safest) way to go about this. Though i'd ask before i got myself electrocuted.

thanks

 

[colin55]

You need to know exactly the characteristic voltage of the LEDs. It is probably NOT 5v.

 

[samuel2801]

**broken link removed**

"required voltage/optimal current for these - Rev volts 5v forward 25mA"

 

[Ubergeek63]

I told you in another thread-12V hockey puck and simple transistor current sources

 

[Andy1845c]

Are these just small LEDs or big multi watt LEDs? If they are small, I would suggest using a wallwart transformer to power them. Post a little more about the exact LEDs you want and how you want them hooked up and we can assist better.

 

[Ubergeek63]

he has junk red 5mm LEDs

 

[Andy1845c]

Are you sure this is the same guy? I know 2 sculpture lighting topics in the span of 2 days is a bit unlikely, but odder things have happened around here....

samuel2801, is this also your topic? https://www.electro-tech-online.com/threads/lighting-up-my-sculpture.90125/

 

[colin55]

""required voltage/optimal current for these - Rev volts 5v forward 25mA""

What is the FORWARD voltage.

 

[Divtech]

Hi
Rev voltage of a red LED is +_ 2.8V the current is ok, (25mA)
It is possible to run it directly from 230V 50Hz or 110 V 60 Hz .How ever it is very dangerous.

 

[tcmtech]

Here is a real world circuit and device I built around six years ago. ITs been plugged in and working ever sinse!
You will still have figure out your capacitor values based on the actual line voltage, frequency and number of LEDs and related voltage drop and running current you are actualy going to use.

D5-D18 are the LEDs in series.

 

[colin55]

Diode D1 is around the wrong way.

 

[ronsimpson]

I usually add a resistor in series with C1. It helps when there is high frequency noise on the power line.

 

[audioguru]

The cheap KingBright LEDs are very dim. Their forward voltage is 2.5V each.

 

[tcmtech]

almost two days before someone noticed and commented?
I am giving that a D- for effort!
Yea I saw that shortly after I drew and posted it. It was an oops at first but I figured I'd leave it as a simple land mine for the read and build students that dont actualy think about how the circuits they pull of chat sites to finish thier homework actualy work!

How many do you think copy and paisted it then tried to build it for an electronics class? Just to get beat down by a simple circuit?

 

[Divtech]

Hi there

To calculate the value of C 1 in your circuit is: Xc = 1/ 2pifc in ohms.
f is the frequency of your apply voltage i.e. 50hZ 230V and C is the value of the capacitor in Farads.