Variable Resistor in Eagle

Hi all,

I'm looking to add a couple of variable resistor to my schematic. I looked in the library but didn't find any variable resistors - only potentiometers (granted they can easily act as variable resistors). My task involves a 3-5V voltage supply creating a 15-50 mA current (so resistance is low) so what model variable resistor or potentiometer do you think would work best? I'm new to Eagle so any advice would be great. Thanks!

0 fritzz over 12 years ago

How is a variable resistor different? Do you mean a trim pot?
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0 Former Member over 12 years ago in reply to fritzz

Well I was hoping for a smaller variable resistor (and while potentiometers can act as variable resistors using only two ports, I wanted to know whether they just had pure variable resistors on there like used in circuitry labs). The potentiometers all seem kinda big, but other concern is their ability to have a low resistance (< 3 ohms).
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0 fidelsalinas over 12 years ago in reply to Former Member

Are you looking for smd rheostat or smd trimmers?
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0 Former Member over 12 years ago in reply to fidelsalinas

Trimmers would work best - those would allow me to keep the resistance at a certain value and then change it if need be (but it would be screwed in). The problem is finding variable resistors that go that low (3 ohms and below).
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0 shabaz over 12 years ago in reply to Former Member

Hi Anup,

Could you share your circuit, component values, and what you're trying to do? It's confusing if you need a current source or something else. Either way, relying on a trimmer alone to provide 3 ohms doesn't sound right.
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0 Former Member over 12 years ago in reply to shabaz

My PCB design is shown above. I initially had put resistors but then realized that a variable resistor would be better in case I wanted to change the resistance to increase the current. What is not shown on here is that there will be a 3.5V-4.0V voltage source that will have each of its pins attached to a variable resistor for each set of LEDs, respectively. The ideal amperage is between 20 and 50 mA. Hope that helps, thanks!
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0 fritzz over 12 years ago in reply to Former Member

50ma is kinda high for an LED.
Maybe you want 20ma, and then less current like 5ma to dim?.

If so, that's about a 20 to 50 ohm resistor, and you could get a 50 ohm
trim pot, but they aren't cheap.
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0 fidelsalinas over 12 years ago in reply to Former Member

TE.com has 50Ohm trimmers
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