John, you bring up a very interesting issue here, and there are a world
of possibilities.
Speakers in general are transducers that convert electrical energy to
motion; the motion of the speaker coil moves the cone it is attached to,
which moves the air, which is what we hear or feel. So, more motion
(easier to feel) usually means louder for them too. Your idea of trying
to remove the paper (speaker cone) could be a good one, if you can
adequately sense the motion to decode the tone.
I am curious though, how do you achieve zero-beat? If you are using an
optical aid, such as some we have seen discussed on this list, what of
the idea of visually decoding the morse? Most navies did this for
decades for inter-ship radio silence, and should prove inoffensive to
the neighbors as well.
Another question, is can you feel the sound pressure of headphone(s)?
Efficient headphones (high sound pressure for a given drive level) have
been discussed on list as well, and if that works for you, it might be a
way to go; one option might be from the Clansman series of UK army
radios, some of which use bone conduction of sound to get it to our
ears; odd looking setup that places the speaker on the rear of your
skull, but it may work as well.
[EMAIL PROTECTED] wrote:
I am interested in determining which earphone (or speaker) would have the
highest physical movement. I am deaf and intend to read morse by feeling the
vibration. Once I have found the earphone/speaker, I then have another
problem. I suspect I will have to find the K2's best audio that fits the device,
then I need to nullify its audio output, since I do not want the neighbours to
be annoyed by loud morse noise. I partially understand how a speaker works
and in order to decrease its audio output I will have to remove or partially
remove the paper which joins the core to the outer body - but will it still
vibrate ?.
It should still vibrate (since its the audio driving the coil that moves
the paper cone), but might be sub-optimal; worth a try if you can find a
cheap speaker with a blown cone - a possible source would be the custom
sound installers for cars; they rip out the old speakers and generally
discard them, so it might be a free source.
Any suggestions would be most welcome.
John G4BOU
If you like the idea of visually decoding it, the tool for visually zero
beating might be usefully adapted to do double duty as a "morse
indicator" as well.
Please let us of developments; we might be able to help more.
73 de Dave, W5SV
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