XTRProf
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Pssst ! Got any spare capacitors ?
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Post by XTRProf on May 10, 2012 5:20:21 GMT
Well, the last Neon bulb on my faithfull extension cord for the Hifi set decided to leave this world to enternity. So I'm thinking of instead of changing to Neon bulbs again, might as well upgrade the tech to the latest hotrod LED. For 230VAC, what is the resistor value and wattage I should use for normal LED brightness when connected to 230 VAC? Here is my quarter of the last century extension cord:
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joethearachnid
Been here a while!
Old head on young shoulders.
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Post by joethearachnid on May 10, 2012 10:39:28 GMT
Pardon me if I'm wrong, but don't LEDs only work connected to DC? I thing you'd need a rather more complicated circuit in that case.
-JoetheArachnid
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Deleted
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Post by Deleted on May 10, 2012 11:25:29 GMT
Pardon me if I'm wrong, but don't LEDs only work connected to DC? I thing you'd need a rather more complicated circuit in that case. -JoetheArachnid www.jaycar.com.au/images_uploaded/ledlaser.pdfYou can also use an appropiately chosen value film type capacitor with suitable voltage ratings, instead of, or in addition to, the series resistor in the .pdf
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XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
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Post by XTRProf on May 10, 2012 15:07:17 GMT
Pardon me if I'm wrong, but don't LEDs only work connected to DC? I thing you'd need a rather more complicated circuit in that case. Actually, since LED is a diode, it will still light in the positve half. As it's at 50 Hz, the LED will not blink much. Only must get the correct value 1/4 or 1/2 W resistor to do the job at 3V.
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Post by gommer on May 10, 2012 15:49:50 GMT
If you would do it with a resistor
power in resistor = 230V * I_led /2 (only half sine conduction).
For only 2mA that means 1/4W, that's going to be blazing hot.
And what about reverse breakdown voltage of the LED?
Nah, I wouldn't risk doing it with a resistor.
Marc
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Deleted
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Post by Deleted on May 10, 2012 20:56:53 GMT
Pardon me if I'm wrong, but don't LEDs only work connected to DC? I thing you'd need a rather more complicated circuit in that case. Actually, since LED is a diode, it will still light in the positve half. As it's at 50 Hz, the LED will not blink much. Only must get the correct value 1/4 or 1/2 W resistor to do the job at 3V. Chong I suggest that you read that Jaycar .pdf, which although worthwhile, only gives a brief explanation,.As Marc has said there is more to it.You should have a minimum of a reverse connected diode across the LED.You could also use a red/green 2 lead LED without the additional diode. Alex P.S. See also, the LED circuits at www.qsl.net/yo5ofh/hobby%20circuits/led_circuits.htm
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XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
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Post by XTRProf on May 11, 2012 0:53:35 GMT
Actually, since LED is a diode, it will still light in the positve half. As it's at 50 Hz, the LED will not blink much. Only must get the correct value 1/4 or 1/2 W resistor to do the job at 3V. Chong I suggest that you read that Jaycar .pdf, which although worthwhile, only gives a brief explanation,.As Marc has said there is more to it.You should have a minimum of a reverse connected diode across the LED.You could also use a red/green 2 lead LED without the additional diode. Alex P.S. See also, the LED circuits at www.qsl.net/yo5ofh/hobby%20circuits/led_circuits.htmThanks for the links. No worries as I wouldn't be doing anything until I'm dead sure as it involves 230 VAC mains. Don't play play there for anyone wanting to mode to LED too.
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