Possibly stupid LED current limiting resistor question.

[skiraly017]

I think I know the answer to my own question but I'm hoping for some confirmation.

I posted earlier about an issue I am having with super bright LED's dying early. General consensus was to up the value of the current limiting resistor. I am using LED holders that have a 2.2k resisitor built in. The current "charge flow" for lack of a better term is -

9v+ > 2.2k resistor > LED > 3PDT switch

I've read before that when it comes to limiting the current to a LED that the resistor can be attached to either side of the LED. If I wire it like this -

9v+ > 2.2k resistor > LED > 10k resistor > 3PDT switch

Have I upped the resistance to 12.2k total? I know the simple solution would be to insert the 10k before the 2.2k, but I'd like to know if a second resistor could be placed between the LED and 3PDT and achieve the desired result. I have placed a resistor between the LED and 3PDT when using two different color LED's in order to make them equally bright so I think that would be limiting the current. Thanks for the help.

[MikeH]

If my "Physiscs of Electricity 102" memory serves correct, you can put the resistance anywhere along the path.  That includes on both sides.  So yes, you are limiting the LED by a total of 12.2K.

You cannot put the resistance in parallel with the LED though.  That is a no-no.

[R.G.]

Have I upped the resistance to 12.2k total? I know the simple solution would be to insert the 10k before the 2.2k, but I'd like to know if a second resistor could be placed between the LED and 3PDT and achieve the desired result.

You and MikeH are both correct. A series string of things acts the same way no matter what order you put them in, as long as you don't look at or tamper with any of the intermediate connections.

[skiraly017]

Thanks, much appreciated!