Hi all, hopefully a simple question for you. Inspired by the retro-looking handsets available for cellphones (
ThinkGeek :: Retro Phone Handset), I thought I'd salvage some components I had and make my own. I got rid of the insides of an old rotary phone handset, and placed a 45Ω speaker (about 1.5cm diameter) and a condenser mic inside, connecting them such that I could connect the lot to my phone (2.5mm stereo jack). Anyway, 2 problems.
The first is that when only the speaker is connected, the sound is very soft, barely audible - would this be fixed by installing, say, a 30Ω speaker?
Secondly, the real show-stopper, if both mic and speaker are connected, and I try to call someone, a terrible squeal is hear on their end (feedback?), as well as on my end. How can this be solved? I don't think it's feedback via sound from the speaker, as it's output is very soft. Any ideas/common pitfalls this may be related to?
Thanks a lot in advance!
PS: I roughly followed this:
Nokia headset / handsfree HDB-5 connector and schematics pinout and wiring @ pinouts.ru