I am currently working on a simple AC Mains Indicator and would love to have a blown fuse indicator on my primary circuit.

After some searching on google, I came accross this circuit:


What I'd like to know is what kinds of LED (the red and green ones) should I use here? Can I use the typical 5mm LED lamps?


closed as unclear what you're asking by clabacchio Nov 16 '17 at 15:32

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It has a 100K Ohm resistor, with 220V and V = I * R <=> I = V / R = 220 / 100,000 = 0.002 A = 2 mA it will barely light up but still ok. So yes, a typical 3 mm or 5 mm can be used. For a lighter diode you can use a less big resistor (most LEDs can have 20 mA or more).

I didn't take the forward voltage into account, but is negligible.

About the LED itself, it shows a bicolor LED, so you can use a typical 3mm or 5mm bicolored LED.


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