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LED power indicator? Answered

Just wondering how to to wire up a LED to show when a project is powered. Eg. push button switch doesn't show on/off.


Use a double-pole switch. These are effectively two switches in one unit, switch the LED on on one side and the project on the other.
Or if it's easy to use the same power supply, run the LED from the same power you switch to the project.


Brilliant! So Simple. Thanks Much!!

I'd venture a guess that paralelling an led + compatible resistor with the regularly switched power supply would do it; shouldn't affect 99% of circuits out there to have a few extra mA draw from the power supply.

I would too, but it may be conceptually simpler to tie the LED to the switch.


It's easiest and the most common practice among engineers if you connect the led up via the board that's being powered, so you can utilize any onboard regulator to reduce the voltage to a usable value, especially if your power source is AC or a higher DC value. It also gives you somewhere to put the limit (dropping) resistor and a single point of contact for both the positive and negative leads to the panel-=mount led.

What's the voltage of the equipment?  If it's 12 v. or less d/c, then just add a regulator and hook an led to the switch so that the switch controls the led also.

This instructable is a good start.