Standard pot pinout?

Go To Last Post
10 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi - I'm planning on using this pot (specifically, the RK09D1130A1L in a board. I want to mark on the silkscreen of my PCB what direction means what. Problem is - I can't tell from the datasheet .

My guess is that, if you place a pot at the center of a clock with the shaft sticking up out of the clock, and with the pins closest to the 6:00 marker, that when you turn the knob clockwise the resistance between the center pin and the pin on the right decreases. That's how I've designed my PCB - but is that correct? I'm going to be sad if my silkscreen is wrong. I don't have time to order the pot in before I have to send out the board, either (well, unless I overnight - which would also make me sad).

Thanks!

edit: I just tested the only two pots I could find around the lab (completely different family from the above mentioned pot) and they both behaved as I had guessed. Is this a standard or a coincidence? Does it mention this on the datasheet somewhere and I'm just not seeing it?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Get one at radio shack, check it with your ohmmeter. Cheaper than turning the board again. I think your analysis is correct.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

You have figured out the standard construction. The resistance is an arc between the two outside pins, and the center pin connects to a wiper that traverses the arc. When the wiper is fully CW, the wiper (center pin) will essentially be touching the right-side pin.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I think you are right. BUT, I have seen a few (very, very few) pots with different pinout. I'd give you c;lose to 99 in 100 that you are right.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

bobgardner wrote:
Get one at radio shack, check it with your ohmmeter. Cheaper than turning the board again. I think your analysis is correct.

I'm paying $12.50 to have the PCBs fabbed. It's cheaper to re-order the PCB than to overnight the pot!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Foo. Boston has BeauCoup electronics stores. Just take one out of an old guitar pedal.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

bobgardner wrote:
Foo. Boston has BeauCoup electronics stores. Just take one out of an old guitar pedal.

Ooo - good reminder for me to change my location in my profile. I just moved and started a new job!

I've checked two pots already - and they both matched what I expected. I just don't have the exact model pot. So I have to hope that the ones I am using match the two I tested.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I've played electric bass for more than 3 decades and done a lot of mods with both amps and instruments, I have never seen a pot being different from what you describe. I'm sure they exist but are extremely rare.

What do differs is how pins are laid out. Can be a straight line or more V-shaped.
Trim pots often have smaller footprint than "normal" pots.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The linked data sheet does have two graphs under "Resistance taper" (page 387)
showing percentage of output vs rotation travel, however rotation direction is not specified.
Most of the outline drawings do state "Shaft shown in full CCW position."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Weird pot functions to watch out for.... 300 deg rotation of shaft but only 90 or 180 deg of variable resistance before the wiper hits the end... used for pan pots or ??. Also 'log' pots where 50% rotation give 10% resistance change, or antilog where 50% rotation gives 90% change.

Imagecraft compiler user