Switching series to pararell  - Page 1
Forum section: electronics / projects

author: RAPo
author_rank: Super Contributor
timestamp: April 18, 2023, 04:35:14 pm
content: I have a set of 5 resistors in series in a circuit with a 10v power supply. I want to have them pararell by flipping a switch (and off course also the other way around).The transition should be as clean as possible, preferably first disconnecting the power. What is the way to do this?

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2023, 05:10:56 pm
content: You want all 5 in series to switch to all 5 in parallel? You could do it fairly easily with relays.Is there a reason you can't just have two separate groups of resistors or even just two resistors, one equivalent to the 5 you have in series and another equivalent to the 5 in parallel? If that would work then it would be easier to do.

author: Picuino
author_rank: Super Contributor
timestamp: April 18, 2023, 05:17:31 pm
content: Why do you need them to be the same 5 resistors? Couldn't you put another 5 resistors in parallel and switch between them?

author: Picuino
author_rank: Super Contributor
timestamp: April 18, 2023, 05:34:37 pm
content: Maybe this circuit can help you.https://www.analog.com/en/products/adg1219.htmlMore circuits like that.https://www.analog.com/en/parametricsearch/10624#/

author: RAPo
author_rank: Super Contributor
timestamp: April 18, 2023, 05:39:11 pm
content: Quote from: Picuino on April 18, 2023, 05:34:37 pmMany thanks, will look into it.

author: Zero999
author_rank: Super Contributor
timestamp: April 18, 2023, 05:47:08 pm
content: What values are the resistors? Analogue switches are only any good for low currents. Relays are required for high currents.

author: RAPo
author_rank: Super Contributor
timestamp: April 18, 2023, 05:48:05 pm
content: Quote from: james_s on April 18, 2023, 05:10:56 pmYes there is a reason: the whole contraption will work either as a set of reference resistors (where you can choose to set your measuring tips) or with the 10V power (precision) supply the same set of resistors can generate a precision current, all in a handy little box.Version 2 of the contraption will expand on that with a set of capacitors and inductors that can be connected either in series/independent/parallel (as displayed in).

author: RAPo
author_rank: Super Contributor
timestamp: April 18, 2023, 05:49:58 pm
content: Quote from: Zero999 on April 18, 2023, 05:47:08 pmThe resistors are precision SMD resistors ranging from 100 ohms to 10M ohm

author: themadhippy
author_rank: Super Contributor
timestamp: April 18, 2023, 06:07:17 pm
content: Quoteguess 630A is low current for a 4 pole double throw switch

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2023, 06:25:05 pm
content: Quote from: themadhippy on April 18, 2023, 06:07:17 pmWhat does that have to do with analog switch ICs?

author: Picuino
author_rank: Super Contributor
timestamp: April 18, 2023, 06:26:01 pm
content: I think making 5 series resistors into 5 parallel resistors is a bit complex and expensive. It is cheaper to duplicate resistors, unless they are of extremely high quality.An interesting projects:https://hackaday.com/2020/05/25/a-diy-electronics-lab-you-can-show-off-with-pride/http://conradhoffman.com/mini_metro_lab.html

author: themadhippy
author_rank: Super Contributor
timestamp: April 18, 2023, 06:34:05 pm
content: Quotenot a lot,however the quote i quoted made no mention of ic,in case you missed itQuote

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2023, 07:57:06 pm
content: Quote from: themadhippy on April 18, 2023, 06:34:05 pmAn "analog switch" is an IC, I've never heard a mechanical switch referred to as an analog switch. Context matters, and from the context it is obvious what he was referring to.

author: donlisms
author_rank: Frequent Contributor
timestamp: April 19, 2023, 06:19:59 am
content: This seems like all you'd need is a 4 pole single throw switch. If you draw the resistors in a zig-zag, you have two gaps to close on each side to make them all parallel. This does not address your "preferably turning off first" issue, but I think that's asking a lot. Maybe you need a 5 pole switch.

author: RAPo
author_rank: Super Contributor
timestamp: April 19, 2023, 11:35:24 am
content: Quote from: donlisms on April 19, 2023, 06:19:59 amThanks.Indeed I was tinkering/experimenting with a 4 pole switch, and the "turning off" aspect is troubling me.