Modding your standard AC/DC 12V power adapter -- which is which?

[BonzaiDuck]

I probably picked up the little 12V power-brick six months ago so I could power fans in my HT("stereo") cabinet crowded with AVR, record-DVD-and-tape players, Gigabit Ethernet switch and my Silly dust HDHR'-'s and tuning-adapters.

These little power bricks are very similar going back decades, whatever the voltage or maximum amperage rating. The DC power connection has an external metal barrel, and a hole in the center for a pin in the matching receptacle.

Instead, I want to strip the two conductors, solder in a Molex plug with yellow and black wires, and from the Molex to a rheostat four-knob fan controller and the fans -- the rest is easy.

So . . . . which part is the +12V, and which is ground? I would suspect there is a consistently-applied convention for these power-pack connectors, regardless the size of the plug.

While I'm waiting for the enlightenment, I'll check the adapter again to see if there's any fine print on the conductor insulation . . .

[But someone among y'all has got to know . . ]

 

[Valantar]

Have you checked if the polarity is marked on the adapter's label? I've seen quite a few laptop power bricks with output polarity marked on them, at least.

 

[bononos]

......

Instead, I want to strip the two conductors, solder in a Molex plug with yellow and black wires, and from the Molex to a rheostat four-knob fan controller and the fans -- the rest is easy.

So . . . . which part is the +12V, and which is ground? I would suspect there is a consistently-applied convention for these power-pack connectors, regardless the size of the plug.

While I'm waiting for the enlightenment, I'll check the adapter again to see if there's any fine print on the conductor insulation . . .

[But someone among y'all has got to know . . ]

What about using a multimeter to check?

 

[pcgeek11]

Look at the power brick it should have something like a half moon shape with a polarity symbol ( this is the outside of the shell or barrel ) and a period with a symbol and that would be the pin or the inside of the shell or barrel.

Or get a meter and check. But then again it is DC and polarity for a fan will only effect which direction the motor turns. Connect it one way and if you need to reverse the direction swap the wires.

Easy.

 

[Red Squirrel]

The polarity is usually marked on it. Typically the middle is positive and outer barrel part is ground. You can also verify this with a multimeter. Put positive probe in hole and negative probe on side. If you get +12v the centre is positive, if you get -12v the centre is negative.

 

[BonzaiDuck]

All good responses and useful to me.

I'm surprised nobody made a joke about either me or the question as "silly."

I DO have a multimeter. But it occurred to me the other day that - yes -- these things should be marked. I really need to look at the brick. But I remember a lot of these things have double black insulated wires, and one has a white stripe.

So thanks again. I will certainly sort this out.

 

[Smoblikat]

All good responses and useful to me.

I'm surprised nobody made a joke about either me or the question as "silly."

I DO have a multimeter. But it occurred to me the other day that - yes -- these things should be marked. I really need to look at the brick. But I remember a lot of these things have double black insulated wires, and one has a white stripe.

So thanks again. I will certainly sort this out.

We have a good group here, I dont usually expect to be ridiculed for having questions. Unlike NASIOC, that place is a ****hole.

 

[BonzaiDuck]

We have a good group here, I dont usually expect to be ridiculed for having questions. Unlike NASIOC, that place is a ****hole.

NASIOC -- "Suburu enthusiasts?!" That's what my web search turned up . . .

I've got so many little projects like this . . . HT-cabinet fan project! I'm overwhelmed! Just made my Saturday run to the county recycling center across town. Dead monitor, dead PSU's, a dead mouse and some other things. Should have waited to build up a bigger load, but this room is starting to look WORSE than a ****hole .. . .

I felt better visiting the local computer shop near the university. If you go inside, you KNOW you'll find some esoteric, obscure item. It's a worse mess in there than is this room. . . .

 

[Valantar]

NASIOC -- "Suburu enthusiasts?!" That's what my web search turned up . . .

I've got so many little projects like this . . . HT-cabinet fan project! I'm overwhelmed! Just made my Saturday run to the county recycling center across town. Dead monitor, dead PSU's, a dead mouse and some other things. Should have waited to build up a bigger load, but this room is starting to look WORSE than a ****hole .. . .

I felt better visiting the local computer shop near the university. If you go inside, you KNOW you'll find some esoteric, obscure item. It's a worse mess in there than is this room. . . .

And it's still in business? Wow. I'd buy everything from there, just to keep it that way. That kind of store is rare.

Also, there is no such thing as 'dead' electronics. They're just sleeping, waiting to be awoken as some odd frankenmonster DIY project. E-waste wouldn't be a problem if everyone just stuffed it in a closet thinking they might use it for something some day

 

[BonzaiDuck]

And it's still in business? Wow. I'd buy everything from there, just to keep it that way. That kind of store is rare.

Also, there is no such thing as 'dead' electronics. They're just sleeping, waiting to be awoken as some odd frankenmonster DIY project. E-waste wouldn't be a problem if everyone just stuffed it in a closet thinking they might use it for something some day

The store is right across the street from me old alma-mater university. The proprietor has been there since 2002, when we bought me old Mom's HP 1200 LaserJet. Tall, gaunt -- he reminds me of the rock star Edgar Winter from the '70s with his hair, adding another 40 years to Edgar's birthday notches.

The place has aspects that are like a computer museum. He had some unit in there from the 50's or 60's.

It looks as though he's "still in business."

The HP 1200 still takes a licking and keeps on ticking. And the printer cartridges are $95 a pop. Moms is famous for erasing vast swaths of national forest, and her paper printed acquisition qualifies by itself for an episode of "Hoarders." For the rest of it -- count on a whole season of such reality-TV episodes.

As for the e-waste, I just put together another 30-lb box of the s*** destined either for our garbage can or the recycler. The recycler asked me (please) do not bring AC power cables, fans or other similar cabling. They want monitors, motherboards -- circuit boards.

I told him that putting the power cables in the landfill seemed like a terrible waste of copper, since we overthrew a duly elected Chilean president around 1973 because of Kennicott and ITT. GEEZ! The local newspapers had done big front-page articles in recent years on "wiring theft" from buildings and housing developments. If somebody is going to steal it, if somebody is going overthrow governments for it -- it must be scarce.

What is WITH those guys at the county recycler? I won't complain.