#atrix lapdock

So, I got myself a 'Lapdock', originally designed to be sold with Motorola Atrix phones, acting as a portable charging dock, netbook-sized screen, and keyboard/touchpad input for the phone. A number of people have also discovered that, as a side effect of using almost-standard connections, the device can function as a cheap, battery-powered HDMI monitor and/or USB keyboard/mouse. And, better yet, as the phone's been discontinued and newer phones (or any phone but the one this was designed for) don't have the exact port configuration and orientation (likely intentional on Motorola's part), these things are going for about $50, used, on eBay right now. So, what's the catch? Models that include a power adapter run a whole lot more than that, power adapters are uncommon and, (almost unreasonably) expensive, and the tip on such power adapters has relatively unusual measurements. Oh, and the cables needed to make it useful to non-Atrix devices are uncommon and either expensive on eBay or available only from Chinese export shops (complete with looong shipping times and relatively high prices, relative to similar, standard cables from the same places).

So, figuring I'd be waiting on a few odd adapters from China for a few weeks, I bought a non-power-adapter model and did some research. Based on my research, not much is available on what size plug is needed, what voltage or amperage is required, or much of anything of the sort, so I did my own experimenting and figure someone else might find this later on and benefit. You're welcome? Just don't blame me if you fry anything.

The 'lapdock', model  SJYN0737A, requests 19 volts at at least 1.58 amps, according to a small label on the bottom. A label near the barrel jack indicates a positive-tip polarity for the barrel connector.

Using a set of digital calipers (recent new toy... dunno how I lived without them!), I got measurements of the power socket itself, and have labelled such on the (remainder of an) index card in the picture above.

(For the visually-impaired and human-impaired, e.g. search engines and people who can't load or see the images, that is: 4.1mm outside diameter, 12.18mm depth, ~1.3mm diameter inner pin, and the inner pin is recessed by about 4.1mm, so it needs a long-ish barrel plug).

After a bit of searching through my room, I found donor a barrel jack of about 11mm in length and 4.0mm in diameter, with an inner diameter that seems about right, but is something I don't have the proper tools to measure. somewhere in the 1.3mm-1.6mm range, I imagine. I attached this through a makeshift adapter to a duplicate adapter-jack on one of those 'universal' laptop power adapters, this one is a Targus (model APA32US) rated at 19.5 volts (and 4.8 or so amps), but any adapter with a stable 19-volt output and enough amperage should work sufficiently.

Notes:

1) There are, apparently, several newer models of 'lapdocks' from Motorola for some of their newer phones, and I have no idea if any of this applies or not. I wouldn't really bet on it.

2) I already had the universal power adapter sitting around, and I used a plug that I had absolutely no use for, but have the funky 'adapter' designed to keep the power adapter itself unmodified and useable for other purposes at will. If I didn't have this sitting around already, buying an official Motorola power adapter from eBay would probably cost me fair bit less than buying the adapter I'm using.

3) I have yet to receive the aforementioned adapter cables, so I have no way of testing any of this outside of watching the 'charging' light slowly pulse (Apple-style, presumably by design... at least I hope so!) and seeing more lights light up on the 'battery fill gauge' thing.