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Hobbyist Power Supply

Lately, I've been looking for a high voltage, high amperage power supply to test a notebook computer. But the local Radio Shack store doesn't even sell a high amperage power supply. It has a few discrete variable power supplies rated at 1.5 A, but that's about as high as it gets. I'm looking for something up to 3 amps. The only power supply that Radio Shack store has rated at 3 amps was a 12 volt power supply, far short of the 16 volts I need.

But I just found the Kensington 33197-RR Certified REFURBISHED 120 Watt Notebook AC/DC Power Adapter for $19.99. (Normally notebook power supplies costs about $60 and up. I am quite surprised to find this one at $20. It's a steal.) It's an universal notebook power supply that works on many brands of notebook. If you ever look at notebook power ratings, you'll see that the voltage and amperage varies greatly from one notebook to another. even if the notebook is the same brand. Here are some examples:

Acer TravelMate 331T:             19V, 2.4A
Acer Aspire 3004WLMi: 19V, 3.42A
Apple Macintosh PowerBook 1400cs: 24V, 1.9A
Averatec 3120V: 19-20V, 3-3.16A
HP Omnibook 500: 19V, 3.16-3.3A
HP Pavilion dv1227us: 18.5V, 3.5A
HP Pavilion dv6119us: 18.5V, 3.5A or 19V, 4.74 A
Sony VAIO PCG-505R: 16V, 2A
Sony VAIO PCG-505TS: 16V, 2A
Sony VAIO PCG-505VX: 16V, 2.5A
Sony VAIO PCG-748: 19.5V, 3A

So, I would assume that if an universal power supply is to work with all these notebooks, it's gotta be able to automatically switch between a wide range of voltage and provide at least 5 amps of current. Now, wouldn't that make an ultimate hobbyist power supply?

I just ordered two of them. Will let you know how they turn out in my experiments.

Chieh Cheng
Sun, 11 May 2008 23:19:02 +0000

Looks like it's going to take a while before they get here. I ordered it on the 11th (Sunday). It got shipped on the 13th (Tuesday). And it's estimated to arrive on the 19th (Monday)!

Chieh Cheng
Wed, 14 May 2008 16:17:14 +0000

I got the Kensington universal notebook adapters. They look very nice; very thin. They are definitely auto-switching between different voltages. They can output 0-24 VDC at 0-6.5 A. It has detachable cables all around. And even include car DC adapter. A LED on top indicates that the unit is getting and producing power.

The only problem, it didn't include any tips. It is suppose to include these tips: N1, N2, N3, N4, N9, N14, N15, N19, N27, N29, N30. That is unfortunately, because the DC output has 5 pins, I have no clue what pin does what. Anyone has a pin-out spec?

Chieh Cheng
Tue, 20 May 2008 06:49:55 +0000

Here is a photo of the Kensington 33197 Universal Power Supply.

Attached Image:

Kensington Universal Power Supply.jpg

Chieh Cheng
Mon, 11 Aug 2008 05:52:57 +0000

Here is the power specification for the power supply.

120V / 2.2A
240V / 1.3A
60 / 50 Hz
12-16V / 11A

0-24VDC / 0-6.5A
120W Max

Attached Image:

Kensington 33197 Power Specification.jpg

Chieh Cheng
Mon, 11 Aug 2008 05:56:09 +0000

2 October 2011

This may be a little late, but this link clues you in:

Basically, the red, white and blue wires connect to a resistive voltage divider
in the adapter tip. White is in the middle of the divider. The voltage ratio
of the divider programs the output voltage. Replace the fixed resistors with a
potentiometer, and you've got a variable power supply.

Which pin is which wire? I don't know. You'll have to cut the cable or do a
little experimenting.

Sun, 02 Oct 2011 22:08:23 +0000

Thanks. That is very interesting read. Too bad the article didn't identify red, white and blue wires. It would have been nice if it explained how came up with these resister values and how he knew what wires to attach them to.

Chieh Cheng
Tue, 04 Oct 2011 00:00:42 +0000

Came across your article. Trying to do the exact same thing. You ever figure this out?

Wed, 22 May 2013 16:46:32 +0400 . . . in case anyone was still interested in this.

Sat, 14 Feb 2015 06:29:45 +0300

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Title: Kensington 33234 Portable 70W Universal AC/DC Power Adapter
Weblog: GearHack
Excerpt: Can the Kensington portable 70w ac/dc power supply be used for other applications like charging an 12v dc emergency light? Thanks
Tracked: Tue, 24 Mar 2015 11:38:16 +0300

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