I followed a link about Waltham DE blades to this page. You'll see what I'm talking about but I have no idea what it means. Also, what is/was a crystal detector? Such cool looking items, now obsolete and antiqued. Makes me appreciate old fashioned wetshaving a little more.
A crystal detector is a device (diode / semiconductor) that converts the Amplitude Modulated radio signal into an audio signal that can be amplified or wired to a crystal headset to create sound. The blued razor (with a layer of carbon on top) and either a steel pin or a lead (not graphite) pencik were the two dissimilar materials that allowed the AM signal to be rectified into a DC Audio current. As stated in the article below even stainless steel items such as hacksaw blades can work in the place of a razor blade if a layer of carbon was topping it (blowtorches work well). http://whatis.techtarget.com/definition/amplitude-modulation-AM http://www.bizarrelabs.com/foxhole.htm BTW: The detector still exist in AM radios today (and other types / bands as well) but is usually incorporated into a single integrated circuit with the amplifier sections and tuning sections combined. Miniturization at work but the exact same physics applies.
I believe for the blades to work, they need to be carbon steel, not stainless. Anyhow, google to the rescue... http://en.wikipedia.org/wiki/Foxhole_radio http://www.instructables.com/id/Build-a-Foxhole-Radio/
There are various crystal radio kits you can buy, radio shack used to sell them I don't know if they still do. My Dad showed me how to make a crystal radio from scratch when I was a kid, from wrapping copper around a toilet paper tube to turning a pink eraser into a suitable radio speaker.
