Observations about the universe, life, Lausanne and me

Saturday, March 22, 2008

Thursday, March 20, 2008

Expensive Equipment

Insulation between the RF electrode and the mass screen.

Material: Macor.

Cost: about 1000 Euro (plus machining).

Tuesday, March 18, 2008

DIY Nokia USB charger cable

My recently bought N800 cannot charge over its USB port (what an utterly stupid design decision!), but the Nokia charger delivers 5V. Since this is the supply voltage of USB, I thought I would buy an adapter. So yesterday I walked into the cell-phone shop and asked. They had one. It cost 79 CHF. (about 50 Euros).

I am afraid I laughed into the face of the poor salesman. He got indignant and told me that he wasn't the one setting the prices. True enough I guess, but I was too busy laughing to reassure him.

Anyway, I decided to build my own USB charger cable. In the photo below you can see the ingredients: (clockwise) A soldering station, callipers, an old Nokia 3.5mm to 2mm converter, shrink-tube and an USB cable in the middle.

I cut of the 2 mm Nokia connector and the male USB connector, and removed the isolation from the cables. Thankfully they are colour-coded: Black for ground and red for 5V. The white and green USB data cables are not needed and get cut off.

Btw, it is important to put on the shrink-tube before soldering anything...

2 minute later: Connections soldered and covered in shrink-tube. I debated whether I should put in a diode, but then couldn't be bothered, and it shouldn't be necessary anyway.

....aaand here we are: Not pretty, but it basically cost nothing, and it does the job.