On this pages you will find informations on how to build the FreeLock Project cable. I have tried to find a solution where one cable fit's all phones. There are 2 ways to build this cable.

1. The schamtic

2. Build the cable with a PCB (not so cheap)

3. Build the cable with a breadboard (cheap)

4. Some pictures of the prototype

If you prefer (1) you have to expose, etch and drill the PCB. This is no easy task (you need a lot of equipment) and it's also not very cheap except you would build a large amount of cables. (2) is very cheap, takes 1 hour to build and all you need is a soldering iron, and some pliers.

But first of all here comes the schematic for the cable.

It's very simple. The circuit is powered via the signals RTS, CTS and DSR, DTR from the RS 232 port of the PC. Via the Diodes D1, D2 the power comes in the right polarity to IC1 the 78L05. IC1 and the capacitors C1-C3 stabilizes the power to 5V because normaly the RS 232 operates at 12V. The RX and TX lines of the PC are connected to IC2 the MAX 232. This IC is responsible for converting the signal levels from the PC RS 232 to the phones M/FBUS level of 3V. The Zenerdiodes D3, D4 acts as a safety function for your phone and are mounted inside the socket for the IC1. Capacitors C4-C7 are needed by IC2 for the conversion. The PC is connected via the 8Pin RJ45 K1 Jack. The signals have the same numbering as on the PC. Only pin 9 of the PC (RI ring indicator) is not needed. With the switch SW1 you can switch on and off +5V for output to the phone. Some phones need a high level of +5V on one pin to enter service mode (like the ERICSSON SH888). For MBUS operation D5 is needed. Please note that D5 is mountet on the bottom of the prototyping version of the cable. Output to the phone goes through the 5pin connector. Depending on the phone you only connect the pins necessary. You will find the cabling schematics on the respective unlock page for the phone.

Building the cable using a PCB

This PCB is dual layered for small size. If you know how to create a PCB it should be no big problem.

 More informations as PDF.

Building the cable using a prototyping board

Start by soldering in the Socket for the MAX 232, the blue bridge and the RJ45 Jack J1. Next solder in the Zenerdiodes D3, D4. Now the Diodes D1, D2. After this solder C3, C5-C7. The area C1, C2 and T1 is a little tricky. First solder C1, C2. Now insert T1 between IC1 and C2. Finish by soldering C4, SW1 and the 5pin jack. Now flip the board. Solder the red bridges. As you can see Diode D5 is mounted on the bottom of the board.

Full view (TOP)

Full view (BOTTOM)

 More informations as PDF.