how to read the lugs of a pot?

[888guitars]

If you read from the top (shaft up) is lug #1 on the left? I cant find a standard?

[Steve Conner]

I've never thought of pots as having #1, 2 and 3 terminals. The terminals are called counterclockwise end, clockwise end and wiper.

[loudthud]

Most schematic programs have this need to give numbers to the terminals on pots, resistors, capacitors, transistors and just about any other component you can name. Even a turret used as a test point gets a pin number of 1. This is necessary so the program can generate a "netlist" that will be used to layout a printed circuit board. Great care must be used when generating symbol and footprint libraries or things won't be connected correctly. A common mistake goes like this: A resistor has two "pins", 1 and 2. An EE fresh out of college can't find the symbol for a pot so he modifies the resistor symbol by adding the wiper and calls it pin 3. He hands the schematic off the a drafter for PCB layout. That person finds in a Bourns data book that terminals are numbered 1, 2, 3 so he uses that for the footprint in the PCB layout. Trouble is, Bourns calls the wiper pin #2. When the circuit boards come back, the pot isn't connected right... Ha Ha. The same thing happends with transistors. Pin 1: Emitter, Pin 2: Base, Pin 3: Collector. Makes perfect sense doesn't it ???

[Enzo]

What they said. There is no 1-2-3 on a pot. The numbers are only there for the convenience of whoever drew the schematic.

The lesson is you should just learn what the terminals do - it isn't cosmic. Then when you read the schematic for something, you see the wiper rather than terminal 2.

Likewise, I don;t like the terms left and right terminals. (middle is still OK to me) Left and right how? Legs up? Legs down? from the shaft side? from the rear?

[Steve Conner]

A common mistake goes like this...
When the circuit boards come back, the pot isn't connected right... Ha Ha.

It's happened to us all I just did the schematic capture for a large board that had a couple of right-angled USB connectors on it. Partway through, we decided we had to change them to vertical mounting ones. I just changed the part codes and sent the revised netlist off to our layout guy, not realising that the vertical ones also had a different pinout, so I should also have swapped those 1, 2, 3 and 4s around in some way. The first I realised was when plugging in a USB mouse shorted out the power supply.

On the bright side, it was only one of a bunch of mistakes on that board, so it's going to need redone anyway.

[Casey4s]

What they said. There is no 1-2-3 on a pot. The numbers are only there for the convenience of whoever drew the schematic.

The lesson is you should just learn what the terminals do - it isn't cosmic. Then when you read the schematic for something, you see the wiper rather than terminal 2.

Likewise, I don;t like the terms left and right terminals. (middle is still OK to me) Left and right how? Legs up? Legs down? from the shaft side? from the rear?

I agree exactly. When I draw a schematic for MY use I number the pots and a few other things to make assembly easier. I like multi can caps and i number those lugs 1 to 5 or 6, it works for me.

But enzo is rigth many of these things have no real standardized numbering system.