Captain Stupid strikes again...

So there are two ON positions and one OFF?

In article , Jerry Peters writes

We call those intermediate switches in the UK (in the context of premises wiring).

scroll down to the "Contact terminology" table.

Ok, something other than an "X" such as a blank box on the data sheet. In my warped mind, "NONE" means "no connection" or "not connected" which sorta implies that there is a terminal or position present. Perhaps organizing the data sheet by the number of positions, instead of the number of poles, might have been useful.

I never make the same mistake twice. It takes about 5 or 10 times for me to get the clue.

BSEE 1971 from Cal Poly, Pomona. I think there's somewhat of a resume on LinkedIn: The education part got truncated when LinkedIn morphed into looking like Facebook. Add CSU Northridge add Santa Monica City College. None of my post employement consulting jobs are listed. For additional entertainment, search for my name in Google Groups: Hmmm... 82541 postings. However, you are correct about being self-taught. Most of what I learned that was useful was post graduation, when I discovered that I really didn't know everything. I read, design, built, and of course, repair.

Should it really require a formal education in electronics to decode a toggle switch data sheet? I don't think so.

Rhetorical question: What's the schematic symbol for a center off switch? I couldn't find anything definitive:

Jeff Liebermann skrev:

No connection is NC

I'd make the viper of the switch rest on a non-connected dot or circle.

Leif

Would "n/a" have worked for you?

It's damn near impossible to get a rattler to do tricks.

The two ends, use 3-way switches, the 4-way switches go in series in the 2 "hot" conductors between the 3-ways. The 4-way switch just exchanges the 2 poles. Say you have inputs 1 & 2 and outputs A & B, the two positions are Position 1: 1->A, 2->B Position 2: 1->B, 2->A.

You may be right, perhaps it was center off. I replaced it for my dad with a regular toggle type dimmer at least 10 years ago. That's the only one I've ever seen, the house was built in 1984-85.

Come to think of it, it may have been center off. Oh boy, knob and tube. I'm trying to deal with that right now.

Greg

True. Unfortunately, this doesn't solve any of the problems and questions I mentioned.

I was hoping to find something in IEC 60617 or ANSI Y32.16 specs.

Incidentally, the proper designation seems to be SPCO (single pole center off) or SPTT (single pole triple throw) as found in: Note that the schematic symbol does not distringuish between these and an ordinary SPDT switch. The problem is that's not the offical ANSI/IEC symbol. See Pg 15 4.3A.1.4 shows a SPDT switch with a center off position. It shows the armature half way between the contacts. There are also many other switch designations that I've only seen on industrial control system schematics. Perhaps a college degree might be helpful in untangling such switches.

How about SPMO (Single Pole Middle Off)?

Yes, one of the on positions is dim, the other full bright. I assume there's a diode in there.

The diode would have to be a selenium rectifier.

Because there weren't a lot of silicon diodes available in the 1930's? (I'm just guessing. I wasn't the one who said it.)

I don't think there were many germanium diodes in the thirties, either.

WWII required development of radar, and that meant going higher and higher in frequency for better resolution. And while they had no problem making transmitting tubes for the higher frequencies, receiving tubes were an issue. So they went back to the "cat's whisker" detector, turning that into a prepackaged germanium diode. And then silicon diodes appeared after the war at some point.

So unless you wanted a tube rectifier, you had no choice but to use a selenium rectifier between the point they came into use (I'm not sure when) and WWII or more likely later. I don't see signs of power solid state diodes till after the war.

Michael

I remember those old selenium rectifiers, they had a distinct smell if they warmed up during their usage, I remember them being used in car battery chargers in the 1940's.

First solid-state rectifier I remember was a 1N34 that I used in a crystal radio in the 1947-48 time frame.