I swear, sometimes I think this stuff is making me dyslexic. So please forgive me for asking a dumb question.
I'm working on a circuit where I need to reduce resistance with a pot.
Let's say, I have a linear pot rated at 100k.
I need the pot to be 100k when turned to all the way down and 0k when turned allt he way up.
Do I need a reverse pot to do this? The problem I have is that reverse pots are typically not linear.
Can I accomplish this just by connecting to pins 2 and 3 and leaving pin 1 unconnected with a standard linear pot?
I'm working on a circuit where I need to reduce resistance with a pot.
Let's say, I have a linear pot rated at 100k.
I need the pot to be 100k when turned to all the way down and 0k when turned allt he way up.
Do I need a reverse pot to do this? The problem I have is that reverse pots are typically not linear.
Can I accomplish this just by connecting to pins 2 and 3 and leaving pin 1 unconnected with a standard linear pot?
Yes. Pins 2 and 3, or if that works the wrong way round just use pins 1 and 2. Do note though that the wiper of a pot is not designed to carry much current, it is only the full element of the pot that is rated at 1 watt or whatever.
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Exactly. Plus, it doesn't hurt to connect the "left over" pin (1) to your wiper – keeps any stray noise that might appear at the "other" (unused) end of the pot from creeping in.
i.e.
__/\/\/\/\/\/\___
|_____↑
I use the maximum rated current for the "whole" pot as an indicator of the absolute maximum current that can pass through the wiper.
i.e. a 400mW 10k pot has a maximum current rating of 6mA.
The wiper current must never exceed 6mA and for long life probably better to aim for <0.6mA
i.e. a 400mW 10k pot has a maximum current rating of 6mA.
The wiper current must never exceed 6mA and for long life probably better to aim for <0.6mA
So, if you connect pin 1 to pin 2, I guess it wouldn't matter if you used pin 1 or pin 2 as the output. Or would you still need to use pin 2 as the out?
Good points about limiting current though the pot. I hadn't considered it, but I'll put on a decoupling cap on it.
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