The Natural Philosopher wrote:

LED
----RES180R---||----
| |
SWITCHED-FEED----||--||--||--||------LAMP
| |
---------||---------


Thats quite neat. Not sure 4 diodes are good ebnough to light the LED
tho. Maybe a power Zenert?

That looks like it ought to put 13mA through the LED with a RMS forward
voltage of about 2.4V which should be plenty.

Must admit I did something similar for a "on charge" indicator in a
constant current battery charger I built a while ago. I found I could
actually get a decent light level out of the LED with only 3 series
silicon diodes (even though by "design" it should have needed more).

(although for this application I think I would just use a neon between
switched live and earth - or across the switch if you want the neon lit
when the switch is off)



--
Cheers,

John.

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