Rotary Switch Parallel Connections

[graphtronics]

Hello Community

How to wire a rotary switch for parallel connections?

Should consider, more than one pole, single dec?

[TimFox]

Please re-write your question for clarity.

[graphtronics]

Parallel connection for passive components

Easy approach use a SPST for each one.
But it take a lot of space and is cumbersome to use.

Ideal approach use a rotary switch add a component in parallel with each position.
Takes less space and easier for user to use.

For instance could use one 4 pole, or 4 deck, to connect 4 components in parallel.
May need to add additional ones for more than 4 components.

[Ian.M]

Four SPSTs and four passives lets you select 16 possible combinations.  Granted, five of the combinations don't have any passives in parallel (either no or a single passive selected) so you *may* be able to reduce it to 11 combinations, i.e. switch ways, but you still need a switch pole for each component and nowadays rotary switches with more than 10 ways and more than 3 poles are as rare as hen's teeth, so a simple solution without any relays and auxiliary power for them is probably impractical.

If you want a better answer you will need to clarify which parallel combinations are required/permitted/desirable, and if there are any extra constraints e.g. operating frequency, max. contact resistance, or max. stray capacitance.

[graphtronics]

Thanks Ian.M

The Hex approach works great up to 16 positions with 4 SPST switches.
Some may find it difficult to grasp the binary approach to select all levels in sequence.

Greyhill series 51 has up to 4 poles with 3 contacts per pole.
Did not find the hen with teeth yet, but will keep eyes open. 
Up to 8 parallel connections can be achieved with two of them.
It requires a bit of creativity for the last one.

Perhaps it can be better explained as a rotary dip switch.
This allows sequential parallel connections.
These are not meant for heavy use.

[Ian.M]

So you want *all* the combos, including the open circuit, and all the single component cases?  You *USED* to be able to buy rotary switches with hexadecimal (4 bit binary) output, e.g. https://www.digikey.co.uk/short/p4z5jw2q but good luck finding one even NOS!  If you find one simply connect the passives in binary order of their effect on the parallel combo each to one bit of the switch, common the other ends and your parallel combo is between the switch common and the passives common.

Greyhill do make the elusive hen's tooth, with 16 positions and 5 decks, but its sealed milspec and you wont like the price or lead time: https://mou.sr/4xvYcBQ

Each deck will have half the ways wired to a particular passive, with the switch wired for hexadecimal coded output.  i.e LSB has every other position wired, next bit up skips two, wires two repeated all the way round, then skip 4, wire 4, and finally the MSB which simply wires the last eight positions.  That leaves you with a spare deck you cant use as the switch doesnt have enough ways for another passive.

IMHO € 330 and 16 week lead time is too much simply to accommodate the hard-of-thinking!  I'd put the binary conversion table directly below or above the SPST switches so its simply find value in the right column of the table then flick switches to match that line, while grumbling about the cost of the panel space to accommodate users who cant math . . .

[Obin]

Maybe to broaden your scope: Switches like these can be very expensive. It might be useful to go for a cheaper rotary switch, like SP16T https://www.digikey.co.uk/en/products/detail/grayhill-inc/51P22-01-1-16N/418013 (which are already quite expensive when buying from non-eastern suppliers), and have it control something like a CD4066 to get more complex patterns.

Do note the internal resistance can be higher on a classic like the CD4066, compared to a mechanical switch.

[themadhippy]

  You *USED* to be able to buy rotary switches with hexadecimal (4 bit binary) output, e.g. https://www.digikey.co.uk/short/p4z5jw2q but good luck finding one even NOS!  I

wot this sorta ting?
https://uk.farnell.com/c/switches-relays/switches/rotary-switches/rotary-coded-switches

[Ian.M]

Well, that's a nice surprise.  There are even some panel mount ones for under a tenner!