Monthly Archives: March 2014

DIY Cellphone, Part 2

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The last couple of days I have been trying to put my cellphone together. Using soldering paste with lead requires good ventilation. The fumes are poisonous and you shouldn’t breathe them. That’s why I had a big fan by my side. Your friends are; soldering paste, flux for the hard ones, a soldering iron, a tweezer and patience.

I discovered that I didn’t receive the correct LiPo charger and I haven’t been able to power the phone in order to program and use it. I have contacted the supplier (Electrokit) and I am sure the they will find and ship the correct one. Still I have to wait over the weekend before I can use my phone, which is not fun =(

Here are some pictures from the soldering procedure:

DIY Cellphone, Part 1

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I believe in a society like today we need to have better control over our communications. Today’s smartphones have been accused of being devices of mass surveillance. Therefore I have decided to build my own cellphone. I found this guide on the internetz, which describes an open source cellphone platform based on a GSM module and an AVR microcontroller. I selected it as a starting point of my cellphone. It will most certainly receive software updates from me (I want snake!), and probably even hardware updates in the future. Yes I know, GSM is not secure at all, and it is vulnerable to man-in-the-middle attacks, but I still prefer the man-in-the-middle over nsa-over-the-internetz.

Enough jabber for now, let’s get to the fun part! So far I have received all the needed components from the Bill of Materials (BOM) for the LCD version of the phone, besides the PAS414HR-VA5R SuperCap, which has been discontinued. Since the proposed replacement part isn’t good enough, I managed to find some left over PAS414HR-VG1 at Farnell and ordered a few of those instead. It will take some scratching and soldering to fit it on the PCB but it’s values are the correct ones. Since I am living in Sweden, I had to find alternative suppliers for my materials (Electrokit for some electronics, In-Time for the antennas, Farnell for the SuperCaps), and some had to be ordered from DigiKey anyway. Try to keep your parts ordered from DigiKey below your country’s import tax threshold, otherwise you might end up paying import taxes like me, which is not fun.

Here is a picture of the PCBs from OSH Park, which are of excellent quality. More will come once I receive the SuperCaps and start soldering the cellphone.

Cellphone PCBs from OSH Park.

Cellphone PCBs from OSH Park.