Disk archival techniques

[Tony Duell]

>  Even so, they had relays then. One can make a useable
> head set with a bar magnet, coil from a relay and
> a tin can. ( Add something to stick things together with.
> There are too many possibilities here to even speculate! )

I read somewhere (I think in Wireless World about 30 years ago) about a 
design for a headphone made from a tin of Sellotape (self-adhesive tape, 
normally used for sticking paper, etc).

You fixed a small magnet in the base of the tin, and wound a coil from 
enammeled copper wire. Suck the coil between strips of Sellotape, then 
stuc that on top of the tin, with more strips of tape to complete the 
'diaphragm'. Apparently it worked reasoanbly well.

There are also some designs for headsets, along with other radio 
components in that very hackish book 'The Voice of the Crystal'. There's 
an add-on book 'Instruments of Ampification' that covers home-made valves 
and transistors (albeit rather poor ones).

-tony