Hi guys, I ran across this electromechanicoustic device (speaker) called a Gallows headphone. This is used as the speaker for a crystal radio. It is pictured about 2/3 of the way down the page. You will understand it's operation by its picture.
I have cross posted looking at this as having three disciplines, acoustics, electronics and magnetics. I would like to see ideas to design one with these objectives in mind. Objectives: Maximum audio from minimal (crystal radio) signal (high sensitivity)
High impedance, if we can get enough wire on the electromagnet, the matching transformer could be eliminated. (100k to 1 meg ohms, tapped) That's a wish :-)
Questions; What should the diaphragm look like? low mass? with ridges? needs to be magnetic at some point.
Can we put an electromagnet on both sides in push pull? Can needs to be sealed.
Earphone is connected with hollow tubing, what type of tube would be low loss? does length matter? I'm thinking stethoscope earphones till something better is found.
Do we want the center of the diaphragm to move or the whole circumference to breath? How do we focus the magnetic field, if we do.
Thanks for your input, MikeK