LED Question

Started by soggybag, September 24, 2006, 12:39:17 PM

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soggybag

Imagine you're wiring up an LED to the third pole on your 3PDT switch, does it matter where you put the resistor? Doe it make a difference if you put the resistor before or after the LED? Here's a picture:

Seljer

nope, no difference at all, doesnt even matter if you're switching the at the V+ side or the gnd side.

If you have a line of components wired in series without anything else shooting off, order is irrellevant

markm

Quote from: Seljer on September 24, 2006, 12:40:44 PM
nope, no difference at all, doesnt even matter if you're switching the at the V+ side or the gnd side.

If you have a line of components wired in series without anything else shooting off, order is irrellevant

....Because series is the total sum of said components, right  ???

soggybag

I figured they were both the same, but I also know that I don't really know what I'm talking about most of the time. This quesiton came up with a friend of mine. I remember reading something about the LED adding noise into the circuit and it occurred to me that the placement of the resister might effect this.

Meanderthal

 You got it Mark, when in series the components become one...
except capacitors...
but with resistors if you think of it as a valve in a water line it dosen't matter which side of the valve you're on, you still only get the same amount of water per min.(volts)
I am not responsible for your imagination.

Seljer

Quote from: markm on September 24, 2006, 12:54:03 PM
Quote from: Seljer on September 24, 2006, 12:40:44 PM
nope, no difference at all, doesnt even matter if you're switching the at the V+ side or the gnd side.

If you have a line of components wired in series without anything else shooting off, order is irrellevant

....Because series is the total sum of said components, right  ???

iirc, RG explained it really well in a thread a short while ago

The Tone God

Quote from: Meanderthal on September 24, 2006, 02:26:05 PM
You got it Mark, when in series the components become one...
except capacitors...
but with resistors if you think of it as a valve in a water line it dosen't matter which side of the valve you're on, you still only get the same amount of water per min.(volts)

Actually with capacitors they still become one when in series just as with resistors they just act in a different manner from what one might expect. If we are to continue with the water analogy a cap would be a holding tank or bucket. I know this sounds like nomenclature nit picking but hey gotta keep things clear around here.

To the OP you can wire the components in any order. The resistor's function is to limit the current to the LED. You can do that on either side of the LED. Current flow doesn't know which side of the part it is on, it just flows so limiting it on either side will result in the same thing in the end.

Andrew