Re: 6v pilot lamp

On 3/14/2024 12:31 AM, UFO wrote:

 Been hearing that a lot for responses.
Since the LED needs I guess 1.5V to be on,
and can burn out with too much voltage, it
did not seem to be a suitable option.

Here's a diagram:
+6V ---resistor---LED---ground
Assuming a red LED you need roughly 1.5 volts
applied to it. That means the resistor has to
drop about 4.5 volts. We want the current to
be 20 mA or less, so we'll choose 10 mA. The
formula to determine the resistance is R=E/I
where E is the voltage to be dropped and I is
the current through the LED. So R = 4.5/.010
That equals 450 ohms, and the closest standard
value is 470 ohms, which will work just fine.
A 1/8 watt resistor is the smallest trough hole
size and may be easier to fit in than a 1/4 watt.
It depends on what you have on hand that will physically
fit - the resistor will use only about .05 watt
The current through the LED does not have to
be exact - anything from say 2ma (often much
lower, depending on the LED) to 20mA will light
it up nicely.  If you want to use a white LED
you can. A white LED needs roughly 3.2 volts
so the resistor value changes to roughly 280 ohms,
which means using a 270 or 330 ohm standard size.
I'd use 330.
Ed