Dear all,

I have a multimeter and want to measure from multiple power sources - switching with rotary switch. I planned to use 2pole Xposition switch to connect one positive and one negative poles at a time but unfortunately I was totally unable to find a suitable one 2P6T, 2.5A... (spent 8 hourch searching). I am considering using single pole switch to switch only positive poles and all negative poles join together - is this possible? The sources will be completely separated (battery, adapter, generator,...) so I don't know what joining all negative poles results in. I guess that their potentials may vary including negative poles.

Please see an image of my original plan (just two sources shown).

Thank you for your help.
BR, joachym

 

hi joa,
Welcome to AAC.
Check this link
https://uk.farnell.com/c/switches-r...witch-positions=4-position&no-of-poles=2-pole

E

 

Do be sure you get a break-before-make switch. That way no unwanted connections will be made.

 

I was totally unable to find a suitable one 2P6T, 2.5A.

The current specification is irrelevant as you will only be switching a voltmeter which will need a very, very low current.

 

The current specification is irrelevant as you will only be switching a voltmeter which will need a very, very low current.

Hi Al,
The switch connects the power source with the output (load) so I all amperage (2,5A max as designed) goes "throught" the switch...
j.

 

hi joa,
Welcome to AAC.
Check this link
https://uk.farnell.com/c/switches-r...witch-positions=4-position&no-of-poles=2-pole

E

Hi Eric,

The first link does not contain what I need - 2 pole, 6 positions (5 different sources plus "disconnect all"), and 2,5A DC (30V, or so)
The second looks more promissing - Although, it is 20V DC maximum and the price is over 400 USD ...

 

Although you will have to deal with \( \text{Rds}_{on} \), it might be good to consider MOSFETs instead of a mechanical switch.

It’s more complicated but will cost less than an oddball switch.

 

Hi Al,
The switch connects the power source with the output (load) so I all amperage (2,5A max as designed) goes "throught" the switch...
j.

OK

 

Although you will have to deal with \( \text{Rds}_{on} \), it might be good to consider MOSFETs instead of a mechanical switch.

It’s more complicated but will cost less than an oddball switch.

Hi Yak,

Unfortunately, I have no idea what you are talking about My vision was simple - choose between wire 1 and wire 2 - more complicated circuits are outside my abilities.

So regardless of other deepness, can I "join" negative poles of different sources without burning my house?

Thanks. j

 

Hi Yak,

Unfortunately, I have no idea what you are talking about My vision was simple - choose between wire 1 and wire 2 - more complicated circuits are outside my abilities.

So regardless of other deepness, can I "join" negative poles of different sources without burning my house?

Thanks. j

IF the power sources are isolated from each other, that is if they are three batteries, for example, there will be no way for current flow to happen. If they are mains supplies, that is powered by being plugged in to the wall, then it is very important that there is no connection from the mains side of the supply to the DC side of the supply, it will also be safe.

BUT you must confirm there is isolation by empirical measurement for safety.

I can imagine the possibility of a switch matrix with multi-pole toggle switches that could prevent connecting more than one source at a time. It might be simplified by using relays acting as an interlock so that all switches must be off before it is possible to select a source, so that if one is on, the others do nothing. If you use a scheme like this, you should include indicators so that you can tell which source is active even if two switches are in the on position.