no more center negative DC-plugs!

[fusionimage]

just started this fanpage
https://www.facebook.com/No-more-center-negative-DC-plugs-108361362856194/

just for fun and not for commecial use, of course

[crispy_tofu]

Sorry I'm a noob, but what's wrong with centre negative DC plugs?

[fusionimage]

nothing; i simply don't like them, as a lot of others

they work well, but most of the dc-plugs are center +

[Stonent]

I just like knowing that the outside is negative so that it is less likely to short out when being pulled out with some shielding nearby.

[fusionimage]

yep, usually you connect the outer side to gnd

[IanB]

I just like knowing that the outside is negative so that it is less likely to short out when being pulled out with some shielding nearby.

yep, usually you connect the outer side to gnd

Well, suppose positive is ground? Then the outside should be positive.

[DimitriP]

Sorry I'm a noob, but what's wrong with centre negative DC plugs?

a) Yes 
b) makes  sense to those that express a preference.
b.1) (Plus witha center positive tucked away, you can't very easily short a +3 and a +20 together by the two outer contact touching each other accidentally (or on purpose).

[DimitriP]

I just like knowing that the outside is negative so that it is less likely to short out when being pulled out with some shielding nearby.

yep, usually you connect the outer side to gnd

Well, suppose positive is ground? Then the outside should be positive.

sounds sparky.... bzzt

[crispy_tofu]

b) makes  sense to those that express a preference.

But it's nice to see why people have preferences for things... 

[jwm_]

I had two experiences with polarity reversal recently.

One is a (cheap. beyond cheap) laser cutter I decided to tear down and see why the fan wasn't working. I was probing around and things sure looked odd... turns out, the "ground" pour was the positive voltage and strapped to the chasis. The connector for the fan had the polarity reversed. it is clear the board was designed for negative ground and somehow bodged to be a positive ground from the weird wires on it and the silkscreen having caps polarity reversed from how they were installed... why or how that was a good idea and cost effective I have no idea. they had a lot of extra PNP power transistors to use up?

Another was more dangerous jumping my friends car battery. I open it up, nice big red terminal and black terminal on the battery, I start hooking up the jumpers and get this uneasy feeling, that red terminal sure looks sort of like it connects to the chasis and the black one sure looks like it feeds into a fuse box... pulled out my fluke 101 (pure coincidence I had it with me. the thing is so tiny I forget i have it) and wouldn't you know it, red terminal was negative, black was positive. That could have been a disaster and them some.

now in my best J walter weatherman voice:
"And that's why we don't have center negative dc plugs."

[Galenbo]

just started this fanpage
https://www.facebook.com/No-more-center-negative-DC-plugs-108361362856194/

I think making DC plugs with negative center is a crime, too.

I have a box with all kinds of adapters, I cut all connectors off from the inverted ones. 

[tautech]

just started this fanpage
https://www.facebook.com/No-more-center-negative-DC-plugs-108361362856194/

I think making DC plugs with negative center is a crime, too.

+1
Except when a reverse polarity protection diode worth a few cents is installed. 

[Jeroen3]

There is a special place in hell for people who chose center negative dc plugs.
That place also exists for those adapters that are sized in a way they take up 3 sockets of the strip. Or that they cover the socket above by hanging over a few mm.

[Gribo]

So what about all those Fluke scope meters? Can I have few of them?

[G7PSK]

I had two experiences with polarity reversal recently.

One is a (cheap. beyond cheap) laser cutter I decided to tear down and see why the fan wasn't working. I was probing around and things sure looked odd... turns out, the "ground" pour was the positive voltage and strapped to the chasis. The connector for the fan had the polarity reversed. it is clear the board was designed for negative ground and somehow bodged to be a positive ground from the weird wires on it and the silkscreen having caps polarity reversed from how they were installed... why or how that was a good idea and cost effective I have no idea. they had a lot of extra PNP power transistors to use up?

Another was more dangerous jumping my friends car battery. I open it up, nice big red terminal and black terminal on the battery, I start hooking up the jumpers and get this uneasy feeling, that red terminal sure looks sort of like it connects to the chasis and the black one sure looks like it feeds into a fuse box... pulled out my fluke 101 (pure coincidence I had it with me. the thing is so tiny I forget i have it) and wouldn't you know it, red terminal was negative, black was positive. That could have been a disaster and them some.

now in my best J walter weatherman voice:
"And that's why we don't have center negative dc plugs."

I had a Vauxhall combo van like that the ground terminal was brown and the live was black. The vehicle was of course negative chassis, I never really noticed the colours were reversed until my father borrowed the van to jump start his car, the next thing I heard was a loud bang as the battery blew up.

[bitslice]

I had a Vauxhall combo van like that the ground terminal was brown and the live was black. The vehicle was of course negative chassis, I never really noticed the colours were reversed until my father borrowed the van to jump start his car, the next thing I heard was a loud bang as the battery blew up.

I had a Vauxhall Corsa and I was trying the same thing, except I noticed the hissing sound before anything melted.

In fact the whole wiring loom was the same combination of weird colours (and labelled in French)

I'm never buying another one 

[BradC]

Center negative DC plugs are used because that way the switched element is +ve not gnd. Don't want to be switching ground references when you are using audio or music gear, so they make the center pin negative.

I always thought it made perfect sense.

[Mashpriborintorg]

The worst I have seen: two modems from the same brand, one in 28.8, the other in 33.6. Same case design, same power supply design and voltage... but one with center negative. Magic smoke was released when I mismatched the power supplies... 

[karoru]

I love the way Nintendo manufactured their NES console (at least American version, don't know about European). Adapter with just transformer inside (same thing was in my old Zoltrix modem from what I remember), rectifier was in the console itself. You could connect anything to it, AC, DC, negative everywhere you wanted, and if the voltage is high enough to power the 7805 and low enough to not melt it it works a treat. Sadly that's not longer a viable options since all that switched mode power supply rubbish;)

[rx8pilot]

DC into a transformer is not a treat.

Sent from my SAMSUNG-SM-G890A using Tapatalk

[karoru]

Transformer was in the wall wart? In the unit there is your usual barrel input, followed by bridge rectifier.

[rx8pilot]

Oh of course. ...yes. SMPS has made things far smaller, lighter, and more efficient. All that at the expense of complexity. Shade tree mechanics step aside......

Sent from my SAMSUNG-SM-G890A using Tapatalk

[John Coloccia]

Center negative DC plugs are used because that way the switched element is +ve not gnd. Don't want to be switching ground references when you are using audio or music gear, so they make the center pin negative.

I always thought it made perfect sense.

That and some other reasons specifically having to do with how effects pedals with batteries and DC jacks are made.

I really don't see the big deal. Transformer output is isolated, so what's the difference where that voltage is sitting? It can't do anything unless it find a path back to the transformer.

[karoru]

Oh of course. ...yes. SMPS has made things far smaller, lighter, and more efficient. All that at the expense of complexity. Shade tree mechanics step aside......

Come on, we're in a topic about reverse polarity on wall wart plugs, and I've pointed out that some old day design has its merits, that's all, I should probably change "SMPS rubbish" to "SMPS black magic" to be more tongue-in-cheek:)

[rx8pilot]

Come on, we're in a topic about reverse polarity on wall wart plugs, and I've pointed out that some old day design has its merits, that's all, I should probably change "SMPS rubbish" to "SMPS black magic" to be more tongue-in-cheek:)

I think you took my post in the wrong way. The intention was to agree with you and point out the down side of the advancement of SMPS.

On the topic, I can't stand center negative DC plugs. In fact, I think the barrel DC plugs are a design past it's day. I only use them when forced and never put them in my designs.