Wiring for a Rotary Switch Mod - Adding Switch to Circuit for Different Cap Valu

Started by trailer, July 02, 2018, 06:11:30 AM

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trailer

July 02, 2018, 06:11:30 AM
I have never wired a rotary up, much less added one to a circuit that doesn't call for it. I have a circuit with a mod to add a rotary on one of the cap pads and then have different cap values on each rotary click. How would I wire a 2p6t rotary into this circuit? I'm looking to have 3-4 clicks on the switch and then have the washer block the remaining spots.

Thanks!

HamSandwich

#1
July 02, 2018, 08:17:11 AM
Your rotary will have the 2 poles in the center and then 12 pigs around the outside. Each pole has a corresponding 6 lugs around the outside, that as you turn the shaft, get connected. This picture should help you out.



For your application, you only need one of the poles. So you'd send a wire from one side of the cap on the board to the center pole you want to use. Attach one leg of each cap to each of the outer lugs. The other end of each cap get soldered together and then all run back to the other pad for the cap on the board.

You can get thrifty and mount the caps across to the other side of the switch, then short all of the unused side of the rotary together and run one wire back from there.

trailer

#2
July 03, 2018, 05:27:04 AM
Quote from: HamSandwich on July 02, 2018, 08:17:11 AM
Your rotary will have the 2 poles in the center and then 12 pigs around the outside. Each pole has a corresponding 6 lugs around the outside, that as you turn the shaft, get connected. This picture should help you out.



For your application, you only need one of the poles. So you'd send a wire from one side of the cap on the board to the center pole you want to use. Attach one leg of each cap to each of the outer lugs. The other end of each cap get soldered together and then all run back to the other pad for the cap on the board.

You can get thrifty and mount the caps across to the other side of the switch, then short all of the unused side of the rotary together and run one wire back from there.

Thank you. I can't say I fully understand but this helps a bunch. The confusing part for me is adding the caps to the rotary. If anyone has a picture of a similar rotary in one of their builds and can snap a picture that would help me a ton.

HamSandwich

#3
July 03, 2018, 06:22:03 AM
This is from Google, but is similar. The only difference is the center lug of your switch is connecting to one side where the cap goes on the PCB, and in the photo, where all of the caps connect together at ground, you're connecting them all together to the other side of where the cap goes on the PCB.

trailer

#4
July 03, 2018, 06:43:27 AM
In my barren brain I thought this is how it would be wired! Maybe I'm learning something? Thanks Ham!

HamSandwich

#5
July 03, 2018, 04:48:41 PM
Quote from: trailer on July 03, 2018, 06:43:27 AM
In my barren brain I thought this is how it would be wired! Maybe I'm learning something? Thanks Ham!

I found the key to understanding switch wiring is the understand how the switch works AND what you want to accomplish. A picture helps, but putting your DMM on connectivity (or resistance) and measuring between pins of switches as you change state really helps. Combine that with knowing what you want to do and visualizing what the circuit looks like with the switch being a simple connection (removing all the bits that are not in the circuit when the switch is in one state), you can tackle and switching problem!

Drawing it out certainly helps too, then tracing your switch in different colors That the signal will take when the switch is in different positions to visualize it.

trailer

#6
October 02, 2018, 06:32:30 AM
I'm back! I have a new request. So I have a 1 pole, 12 position rotary switch (Alpha). How would I lock this switch into less positions like if I only wanted 6 positions? I checked Alpha's site but didn't see anything about it. There is a rubber boot around the guts of the switch and I don't want to take it apart till I know I can get the job done.

Thanks!

HamSandwich

#7
October 02, 2018, 06:52:29 AM
There's a washer with a little nub underneath the nut that mounts the rotary switch to an enclosure. You have to put that nub down into one of the numbered (I think they are numbered) holes. That will set how far you can turn the switch.

trailer

#8
October 03, 2018, 05:42:16 AM
Quote from: HamSandwich on October 02, 2018, 06:52:29 AM
There's a washer with a little nub underneath the nut that mounts the rotary switch to an enclosure. You have to put that nub down into one of the numbered (I think they are numbered) holes. That will set how far you can turn the switch.

I took a look at the switches I have and don't believe mine can be locket into less positions. I definitely don't have the washer with the tab. Mine are this style...

https://www.taydaelectronics.com/rotary-switch-1-pole-12-position-alpha-sr2511.html

Anybody have any suggestions or better yet, a link to the style you have used?

trailer

#10
October 03, 2018, 08:19:51 AM
Quote from: dan.schumaker on October 03, 2018, 05:47:56 AM
This one would work for you.  It has the pin to set the number of positions.

http://www.smallbear-electronics.mybigcommerce.com/26mm-enclosed-1p2-12t/

I figured my switch just wasn't going to work. No worries though. I'll just make a full 12 positions on some fuzz down the line.

Thanks for the help folks. I'll update when I get this thing fired up.
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