Archive for the ‘Cool Stuff’ Category.

Charging a Thinkpad using a Dell AC adapter

When I recently bought a used X60s Thinkpad, to replace my even older x40, this also meant that I’ll need to replace my ~6 AC adapters that I have in all the locations where I could possibly want to charge my laptop. Buying 5 more adapters was not a solution as it would have been to expensive. At work we use Dell laptops, so I have access to as many AC adapters as I could possibly need.
The Dell adapters are rated at 19.5V whereas the Lenovo adapters are 20.0V. That isn’t an issue, so it was looking good. The connector looked very similar, however it doesn’t fit.
Now one option would be replacing the connector, but I found a better option:

Removing the modem’s RJ11 (or is it RJ10, doesn’t matter) connector, and installing a Dell DC jack looks way better in my eyes. So this is what I’ve done:

After removing the shield that holds down the DC jack + modem port, I’ve figured out, that there’s just about enough space to place the dell jack (out of a docking station) where the modem port used to be.
After some thinking, I’ve decided to drill two holes and solder the ground pins of the DC jack directly to the shield, this holds the whole jack in place, and also provides ground connectivity – one less cable.
To connect the + I’ve added some copper wire which connects to the + terminal on the original Jack.

You should be aware, that the center pin isn’t the + connection but a data line, that lets your laptop communicate with the AC adapter. I don’t know anything about this protocol, but as I found out, it’s not necessary to connect this pin to the dell adapter (and it most likely isn’t the same protocol anyway).

This is how it looks:

Yet another Lux-RC / Easy2Led bike light

Training off-road during the colder days often also means that it’s getting quite dark. There are lots of bike lights on the market, most of them are either too expensive or not 100% satisfying. There’s however a simple solution using components from Lux-Rc and Easy2Led.

Lux-Rc light engine:

A small board, 3 leds and a boost regulator is already integrated, different configurations are available

Easy2Led light housing:

A good fit for the L33X light engine from Lux-Rc, in addition you’ll need a handlebar mount (Lupine or the Chinese equivalent that can be ordered at Lux-Rc), cables, battery, a momentary switch.


Input voltage depends on the light engine, mine is optimized for 2s Li-Ion batteries, I’m not going into detail about building a Li-Ion battery pack. This is dangerous, and you should know what you do, or better leave it. My battery pack has some additional heat-shrink tubing over each individual cell, heat shrink tube over the whole pack, and then a layer of plastidip liquid rubber on top of the heat-shrink tubing. Additionally, I’ve added some foamed rubber on the side that touches the frame when the Pack is mounted to my bike.

Oh yeah, and please use a little less thermal glue, maybe 1/3rd of what I’ve used should be enough.

Having a cold beer on a boat.

I prefer having a cold beer when I’m on our boat, but since this is usually on the sunny days, the performance of our fridge (Waeco CF-18) was too weak to cool one down in a short time (temperature in the cabin goes up to ~35° C if the sun is burning down).

I’ve been thinking about some kind of a GSM-based remote control, and actually found a nice product called microguard. The product seemed perfect, relatively cheap, easy to implement, available, but there was no time-out that could be set. Even if I have a separate starter-battery, it was key to find a solution that turns off the fridge after a given time without user interaction. Luckily, the guy who runs microguard was very cooperative, and added a timeout feature for me (and everyone else of course).

The module now turns on a relay for two hours after it’s been called from my or one of 4 other predefined phones. this is a bit on the short side, but I can live with calling twice.

This is how my installation looks:

From left to right:
Charge split diode / Rear side of main switches / Fridge fuse / Microguard module with relays, cables, mounted on an a plastic case / RedBull cup as holder for a Siemens S45.
The Cat5 network cabling goes directly to the voltmeters on the dash, this was made to show the exact voltage without loss due to load on the cabling.

As mentioned before, I have two separate batteries the starter is a traditional lead/acid battery, and the domestic is an AGM type, which allows deep cycles.

This is how the battery compartment looks:


The switches on the left are starter / jumper / domestic. This allows maximum flexibility. The domestic main switch actually doesn’t kill the microguard / fridge, so it can be off, and I can still call the fridge.