Overview

By making use of the two low cost development boards below:

(A) CH340 USB TTL Serial Adapter for Arduino like FTDI CP2102 PL2303 approximate cost £2.99

(B) HC-05 6 Pin Wireless Bluetooth RF Transceiver Module Serial For Arduino approximate cost £2.50

(A)          (B)

A simple bluetooth serial convertor can be constructed.

To assemble the interface, we can either directly connect the two modules together with the cable loom supplied with the USB to serial adaptor or by constructing a linking board from prototyping PCB.

Whichever way is chosen the two modules should be connected together in the following manner:

Note: Here the USB to serial converter has been switched to 3.3V  

Circuit

Cable Connections

As stated above the connections can be achieved by directly linking the modules with the supplied loom, the end result is a bit fragile but dose work.

Stripboard Link Board

Alternatively if you require somthing a bit more permanent then a small link board can be manufactured out of stripboard as below:

 The three componets for the bluetooth module are then ready for assembly.

Once assembled the unit then has the following appearance.

Testing

The assembly was then tested in the same manner as revision A with RealTerm running on the PC and a suitable bluetooth serial program running on an android device.(see links below for the software I used to test the device)
 

Links:

http://realterm.sourceforge.net/

https://play.google.com/store/apps/details?id=Qwerty.BluetoothTerminal&hl=en