[sam]

hey guys
i purchased 2 sales listed as philco speakers 1 was a steal other inflated by seller but still cheep.
question is i belive they are mic`s as i have seen them before . 1 has a wire that goes to black box at top in rear of cabnet i opened it up looks like speaker to me ??

[Bill Kinghorn]

I bet it is intended as a mic but is just a small speaker. The low Z is boosted by the box which is an input transformer.

[Bill Kinghorn]

Almost all passive electrical machinery is reciprocal.

[Electrothaumaturgist]

Yes. I seem to recall (in the dark, distant past), during "experiments", I was able to use a speaker as kind of a microphone. Odd, but semi-effective. Could be a hybrid?

[codefox1]

Dunno about that, but a small PM speaker makes a very good microphone, just use an output transformer in reverse. Done all the times in old time intercoms. In fact they sometimes used 45 ohm PM speakers to minimize losses in wiring from remotes to masters. Dunno about modern ones though.

[sam]

thanks guys
i only seen one with the radio for sale but was way to expencive for me
i see them on ebay but no cords as this one has cord i see where it goes .it dosen`t say any about it on my schamtic`s
now all i need is plater to motor cupler and it is complete
amazing a speaker can be a mic too!!
sam