Basic question - input selector switch

rayma

Member
2011-04-29 8:37 pm
I'm designing a simple 3 pole 4 input selector switch and need a little help:
is it important what I connect first? Ground or lines? Or it doesn't matter?

Usually the input grounds are all permanently connected. If you want to switch the grounds also,
use a make before break type of switch so you don't get loud noises. This will keep all the grounds
connected while the inputs are switched.
 
I'm designing a simple 3 pole 4 input selector switch and need a little help: is it important what I connect first? Ground or lines? Or it doesn't matter?


There is a fairly universal rule: Connect grounds before signals, and inputs before outputs.

So if all are present as separate lines, then the Ideal Order becomes:

To connect when all four lines are present the order then becomes as needed:

(1) Connect input ground.
(2) Connect input signal and output ground.
(3) Connect output signal.

To disconnect when all four lines are present the order then becomes as needed:

(1) Disconnect output signal
(2) Disconnect output ground and input signal
(3) Disconnect input ground


Often the grounds are permanently connected together, as others have observed. YOu have no choice, so just leave them permanently connection.
 

peroz

Member
2014-03-24 9:52 pm
I decided to go with a bought switch and got myself the one in the picture. It is a 3 pole 4 position switch, so as far as I understand, I can either swotch the grounds or use the third pole for switching indicator LEDs.
But what I don't quite get is, why the switch clicks 11 times from left to right, if it is a 4 pos switch:) Any ideas?
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Most 3-pole 4-way switches are mechanically similar to a 1-pole 12-way switch (so 11 clicks). They have extra contacts for the extra two poles, and a device for limiting rotation to just 4 positions. If this rotation limit is missing, or not fully inserted - often the case before the switch is mounted in a panel - then you can turn all the way.