Once again here is a true recycling project – turning an yesteryear’s telephone handset into a general purpose retro handset for today’s mobile phones. Recently, I bought one piece of the trendy “mobile phone retro hansdset” from an online store. Unfortunately the cheap, chinese-made, little gizmo failed to reach up to my expectations both in physical and technical aspects. Thereafter, I leaped into this green electronics project, realized with the help of a few cannibalized components and parts.
First of all, look for and gather one telephone handset (ofcourse with its coiled-cord) from a discarded telephone. Next, ensure that mouthpiece (microphone) and earpiece (speaker) mounted inside the handle are in working condition, and keep an eye on its wiring. Usually yellow (+) and black (-) wires of the coiled-cord are for the speaker, and red (+) and green (-) wires are for the microphone, but not guaranteed. Incase of a doubt, try to open the handset carefully and take a clear note about its internal wiring, just before the starting of the actual construction.
For the 3.5mm mobile phone headset jack, fix up such an old jack with short-length of wires which can be trim down from an unused mobile headset. Now interconnect the telephone handset with the 3.5mm headset jack as shown in the final wiring diagram.
Finally, note that this is not a universal solution. In case of a mismatch* between the internal electronics of your mobile phone and the impedance/electrical properties of the transducers in your telephone handset, some discrepancies may occur. So always use this non-standard accessory at your own risk!