Help with Wiring an Octopus Tester - Page 1
Forum section: electronics / testgear

author: Generalquark
author_rank: Contributor
timestamp: February 01, 2020, 10:59:41 pm
content: Hi,I am trying to build the circuit below, and I know I have a dumb question, but I am struggling to figure it out. I have a switch that is supposed to be 2 pole 3 positions, but I am struggling to determine how to wire this switch to the board.This is the switch I havehttps://www.digikey.com/products/en?keywords=CKN11018-NDIt has 8 pins.These are the shorted connections in each of the 3 switch positionsSwitch Position 1: 1 to 2 shorted and 5 to 6 shortedSwitch Position 2: 1 to 8 shorted and 4 to 5 shortedSwitch Position 3: 2 to 3 shorted and 6 to 7 shortedCould someone help with the wiring of the switch. I am struggling with the single tap off the ground pots.Thanks

author: Whales
author_rank: Super Contributor
timestamp: February 02, 2020, 01:38:40 am
content: Am I blind? The datasheet for that part doesn't show any wiring info or pattern info. Maybe it's an assumed pattern in the industry? Your results from buzzing out the pins are not what I'd expect at all either.If you can: make it without the switches for now. Test it with some resistor values and make sure this particular design works the way you want it to before trying to make it perfect.N.B thedesign I once usedwas much simpler.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 02, 2020, 02:17:40 am
content: It doesn't look like that part has a common connection for each of the poles so I don't think it will work for your circuit.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 02, 2020, 02:24:18 am
content: Whoops. I think this is the right screenshot from the datasheet.

author: tooki
author_rank: Super Contributor
timestamp: February 02, 2020, 09:55:08 am
content: The datasheet says: “F1XX, F2XX models: No common terminal is present. Switching function is provided by movable contacts shorting adjacent pairs of stationary contacts.”You have an F203.I don’t think it can be used for your application.

author: Generalquark
author_rank: Contributor
timestamp: February 02, 2020, 01:47:41 pm
content: Even though that's unfortunate (because I purchased two), I am thankful that 3 days of racking my brain over why this would not work was not because I missed something easy. Is the schematic wrong then when it calls out for a 2 pole 3 position switch? Should it Be 3 pole 3 position or is there a 2 pole 3 position with a common? I don't have much experience with higher complexity switches. Does anyone have a suggestion on a good switch to use. (Trying to stay on the lower cost end.) Thanks a bunch for the help.

author: Generalquark
author_rank: Contributor
timestamp: February 02, 2020, 02:02:35 pm
content: Do you think I could purchase this kit and use the 2 pole 6 way switch, but tie A and C together?https://www.amazon.com/3pdt-Rotary-Switch-Assortment-Positions/dp/B07148LW93/ref=sr_1_2?keywords=rotary+switch+assortment&qid=1580651828&sr=8-2

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 02, 2020, 04:42:03 pm
content: Quote from: Generalquark on February 02, 2020, 02:02:35 pmYou wouldn't want to tie A and C together but could use the switch by tying 1 & 4, 2 & 5, 3 & 6, 7 & 10, 8 & 11, and 9 & 12.

author: Generalquark
author_rank: Contributor
timestamp: February 02, 2020, 06:15:51 pm
content: So then would Position 1 be 1, 4, and CPosition 2 be 2, 5, and CPosition 3 be 3, 6, and C?If yes, then wouldn't there always be current going to through all 3 paths, but only one at a time going to the common and therefore to vertical axis?

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 02, 2020, 07:16:45 pm
content: The A and C terminals are the two poles (commons.) All the numbered terminals are the throws (positions.)For the A pole...Positions 1 and 4 would short to A.Positions 2 and 5 would short to A.Positions 3 and 6 would short to A.For the C pole...Positions 7 and 10 would short to C.Positions 8 and 11 would short to C.Positions 9 and 12 would short to C.The poles correspond to the 'Vertical Y Axis' node of your schematic. The throws would connect to the trim pots.I see that there are 2P3T switches on Amazon. Unfortunately, they don't show a diagram of how they are connected, so if you were to buy one you might wind up with something similar to what you already have. I doubt that you would, though, since that is not a common type of 2P3T switch. I don't know if the manufacturer should even use that term since '2P3T' would normally mean the type of switch used in your schematic.

author: AVGresponding
author_rank: Super Contributor
timestamp: February 03, 2020, 11:15:00 am
content: Lorlin make multi-position multi-pole switches with properly defined poles. They also make modular "wafer" switches, where you can custom build the number of poles and positions you need.https://lorlinelectronics.co.uk/product/ptUsing "wafer switch" as a search term might help you find a more local supplier/manufacturer.