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Trimmer

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SnaRf

New Member
Hey all.

OK, I am band new, both to electronics and to the forums.

So, I put a question to you all.
I did a search on the word "trimmer" and got a few hits.
But it didn't quite clear up my confusion.

I am attempting to build this.

however, the person did not go into a detailed "howto", and as I said I am pretty much a n00b.

Now, the actual question:
In there he uses a variable resistor/pot/trimmer.
I managed to sourse a trimmer, but I don't quite understand how it works.

It's got 3 pins at the bottom.
From the previous search I did, it seems like you only need to wire up 2 of them to use it
as a variable resistor (Increasin or decreasing the current that passes through it).

Can anyone explain to me in layman's terms how to wire this up?
I am guessing there's a + and - side on the trimmer, and that it is simply wired in serial.

Am I guessing right?
 

ChrisP

Member
Simply put, a trimmer is a three-terminal variable resistor. In the circuit described, two of these three termnals are used. The resistance measured from one end of the trimmer to the other is the nominal resistance of the device -- in this case, 10K-ohms. The ressitance measured from either end to the center terminal (the "wiper" or "traveler") will vary from a maximum of the devices nominal value to zero, depending upon the position of the traveler along the length of the resistive element.

Your circuit uses one end terminal and the traveler terminal. Which end terminal is used does not really matter -- the only difference that would be made by selecting one or the other is which way the effective resistance varies with control operation. With one terminal selected, the resistance will increase with clockwise rotation, while it will decrease with clockwise rotation if the opposite end terminal is used.
 

SnaRf

New Member
Thanks.

You'll see more of me here as I try and figure out how that circuit's gonna work

:)
 
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