Re: very simplistic potentiometer question

Barbara wrote:
> I am just beginning to tinker with electronics. I've decided to start
> very simply and work my way up to the fun stuff. I like the thought
> of playing with LEDs for some reason so I'm starting there. I've
> figured out already that without a resistor that LEDs last about .2
> seconds before they fry. Now that I can keep one going for more than
> 5 seconds I'd like to add a pot to control the brightness. I know a
> pot is a variable resistor that basically adds resistance. I had this
> idea that I would simply insert it between my resistor and the
> positive lead on my power source (a 9 volt battery in this case.) I
> bought an assortment pack of pots and was astonished to find they have
> 3 leads. This doesn't fit into my notion of how they work so I am
> obviously missing the big picture here. I figure the answer is simple
> sow I've done a lot of searches on Google and yahoo and I can't find
> simple enough circuits to make sense of how they work. I need some
> basic info on how to wire a circuit using one led, a resistor, a pot
> and a battery.
>
> Barb

The outside pins connect to the ends of a resistive track. The middle pin
is the wiper. You can just use the middle pin and one outside pin to get a
variable resistor like you imagined. You'll get best results from low-value
pots (try 1K) and, of course, you *must* retain the fixed resistor in series
as well to avoid frying the LED when the wiper reaches the end. With this
rather crude method, you'll find the brightness varies non-linearly along
the track.


.

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