The light bulb of the pilot light on my Perreaux SM3 was broken when I bought it. As far as I can tell the bulb is 5mm. The voltage leading to the lamp measures 42.4v. Any idea what lamp I should go for?
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Photo? Bulbs come in many formats. I have a large collection, some use sockets, some have wire leads. The socketed one use all manner of socket types. SOme bayonet, some fuse clip style, etc.
A bulb might run on such voltage, but if it is open, a series resistor will not be able to drop any voltage. Same for LEDs in fact. A dropping resistor requires current to flow to drop voltage.
LEDs come as parts, but there are also LEDs in small housings with integrated resistor.
A bulb might run on such voltage, but if it is open, a series resistor will not be able to drop any voltage. Same for LEDs in fact. A dropping resistor requires current to flow to drop voltage.
LEDs come as parts, but there are also LEDs in small housings with integrated resistor.
This is a photo of the light bulb. It's attached to two wires directly via a 'socket' (round disc with two holes at the top of photo).
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and a bit of heatshrink to avoid shorts but probably best not to cover the resistor body.
White or blue LED.
The LED will not need its full rated current for an indicator lamp.
Check the resistor dissipation - 42V is a lot to drop.
White or blue LED.
The LED will not need its full rated current for an indicator lamp.
Check the resistor dissipation - 42V is a lot to drop.
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40v at 10ma (ballpark LED current) gets ma a 4000 ohm resistor. And that current would dissipate about 400mw, so a 1 watt resistor or maybe 2w to be nice.
AC or DC supply? Might need a protection diode in series.
If AC supply, a series cap can limit the current.
If AC supply, a series cap can limit the current.