All About Circuits Forum Toggle Switch Terminology
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#1
10-14-2013, 10:20 PM
 jvcmarine New Member Join Date: Mar 2012 Location: SE Mass Posts: 3
Toggle Switch Terminology

I know I'm getting old when I can't recall basic stuff, or maybe I'm just a dumb ass!

Looking at toggle switches.

DPDT. I assume this switch would have six contacts and have three detente positions, down, middle up, or left, middle right. LOL.

Below are the descriptions from the Carling data sheet.

I have two questions:

1: What is the difference between Off and None.
2: What do the parenthesis mean.
3:Why don't they provide a switch schematic.
ok I know that's three.

ON-NONE-OFF

(ON)-NONE-OFF

ON-NONE-(OFF)

ON-NONE-ON

ON-NONE-(ON)

ON-OFF-ON

ON-OFF-(ON)

(ON-OFF-(ON)
#2
10-14-2013, 10:27 PM
 #12 Senior Member Join Date: Nov 2010 Location: 15 miles west of Tampa, Florida Posts: 9,048 Blog Entries: 9

The parenthesis means momentary.
Who knows what, "none" means?
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#3
10-14-2013, 10:36 PM

Quote:
 Originally Posted by jvcmarine DPDT. I assume this switch would have six contacts and have three detente positions, down, middle up, or left, middle right. LOL.
DPDT = 4 contacts, and if not specified 'Center Off' then only two positions.

Quote:
 Originally Posted by jvcmarine I have two questions: 1: What is the difference between Off and None. 2: What do the parenthesis mean. 3:Why don't they provide a switch schematic. ok I know that's three. ON-NONE-OFF (ON)-NONE-OFF ON-NONE-(OFF) ON-NONE-ON ON-NONE-(ON) ON-OFF-ON ON-OFF-(ON) (ON-OFF-(ON)
Never seen most of those descriptions, I am assuming the NONE means centre off?
Max.
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#4
10-14-2013, 10:37 PM
 WBahn Senior Member Join Date: Apr 2012 Location: Larkspur, Colorado Posts: 8,068 Blog Entries: 9

It means there is no center position at all, as opposed to OFF, which means that there is a stable center position in which neither of the circuits is connected.

So a typical SPDT switch used for a stairwell light would be ON-None-ON.
#5
10-14-2013, 10:43 PM

That seems a bit redundant specifying NONE for a position that does not exist?
I am used to SPDT - Centre Off, or ON-OFF-ON for a three position switch.
If simply SPDT then this would automatically be assumed as a two position switch?
Max.
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#6
10-14-2013, 10:44 PM
 WBahn Senior Member Join Date: Apr 2012 Location: Larkspur, Colorado Posts: 8,068 Blog Entries: 9

If those are the options listed specifically for a DPDT switch, then I don't have any idea what something like ON-None-OFF would mean. It's a double throw switch, which means there needs to be two "ON" states in there somewhere. So the first three listings don't make sense to me.

Other possibilities, though probably custom order, would be something like

ON-ON-(OFF)

meaning that the one side and the center positions connect the common pole to the two circuits and that the other side is a momentary that disconnects both circuit but that returns to the center ON position when released.
#7
10-14-2013, 10:50 PM
 MrChips Super Moderator Join Date: Oct 2009 Posts: 8,994 Blog Entries: 23

SPST OFF-None-ON
SPDT ON-None-ON
SPDT-Center Off ON-OFF-ON

Any (ON) means it is momentary, i.e. spring return to previous position when released.

For example,
(ON)-OFF-(ON) is a SPDT that returns to centre OFF when pushed to either side and released.
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#8
10-14-2013, 10:58 PM
 WBahn Senior Member Join Date: Apr 2012 Location: Larkspur, Colorado Posts: 8,068 Blog Entries: 9

Using the None simply makes it so that data sheet tables can be made in a consistent way. For instance:

 Option Code Left Center Right A3 ON OFF ON B7 (ON) OFF ON B9 ON NONE ON C1 (ON) ON (OFF)

It also allows unambiguous encoding in a parts database.
#9
10-14-2013, 11:01 PM

Then what would a maintained SPDT centre off be, in post #5 the ON-OFF-ON would be maintained, if not it would be labeled Momentary. ?
It seems to me those descriptions by the OP is confusing and using descriptions that vary from the industry norm, which usually are self explanatory?
Max.
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#10
10-14-2013, 11:07 PM
 WBahn Senior Member Join Date: Apr 2012 Location: Larkspur, Colorado Posts: 8,068 Blog Entries: 9

Quote:
 Originally Posted by MrChips For example, (ON)-OFF-(ON) is a SPDT that returns to centre OFF when pushed to either side and released.
How do you know this is a single pole switch and not a double pole or even an 8-throw switch?

This encoding tells you how many throws there are, but nothing about how many poles.

It also doesn't given any hint about make-before-break conditions designed into the switch. I've seen a simple encoding that included that but can't recall for sure exactly what it was. I believe it just an added a '+' or '-' between adjacent positions with a '+' meaning make-before-break and a '-' meaning break-before-make. Either could be used if the adjacent is an OFF but I think the '-' was used as a default.

So something like

(ON)+ON-OFF

meant that the two adjacent ON positions, the extreme one of which was momentary, and that a make-before-break action joined them.

Using this encoding, a two position (no center position) SPDT switch with make-before-break would appear as

ON+NONE+ON

while the same switch with break-before-make would appear as

ON-NONE-ON

 Tags switch, terminology, toggle

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