piclist 1998\10\21\091218a >
Thread: Simplest way to drive LED from mains 230V
face BY : cousens@@spam@her.forthnet.gr

Nigel Orr- Underwater Acoustics Group wrote:
> This is a little different from the discussions which have been going on
> recently- I don't need to power a circuit from the mains, but a simple
> isolated logic level input.  My feeling is that it would be best to drive
> the LED in an opto-isolator from a stepped down mains supply, but I'm not
> sure what the easiest way is to do it.
> Simplest would seem to be a resistor, series diode, and zener, to give some
> protection to the LED, with maybe a capacitor and bleed resistor in
> parallel to stop the LED flashing at 50Hz- is this worth pursuing,

Though 15ma 220v = 3.3 watts waste heat, a .22uf cap will give you 15ma
bridge rectified, as mentioned before use mains rated cap and
a series resistor as fuse/inrush limiter.
after the bridge a 5v6 zener 10uf cap and a 220 ohm to your led
(max approx 18ma)

Peter Cousens
email: spam_OUTcousensspamspamBeGoneher.forthnet.gr  phone: + 3081 380534
snailmail:  Folia, Agia Fotini, Karteros, Heraklion  Crete, Greece.

Is it true that they have, on the new version of windows
managed to increase the MTBF from 95 to 98 minutes ?
(That's why they called it 95)

<362DEB05.3C07@her.forthnet.gr> 7bit

See also: www.piclist.com/techref/displays.htm?key=led
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Subject (change) Simplest way to drive LED from mains 230V

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