Building your own diodes
During World War I, soldiers in the field made their own radios to listen to programs for entertainment and news. They had access to wire from broken down vehicles, and telephone receivers, but they did not have modern solid state diodes in little glass tubes.
However, it is surprising to find out just how many ordinary objects can act as a diode, letting current flow one way better than another.
This is where i got the idea.
This is how we made our diodes:
Take a small length of glass or plastic tubing–an inch of the case of a plastic pen works well. Close one end with wax, sealing a wire through the wax. Pour a little copper oxide into the tube: enough to cover the end of the wire. Fill the rest of the tube with copper filings or turnings. Poke a wire into the copper filings or turnings (but don’t let it go down to the oxide) and seal the end of the tube with wax.
Can’t find copper oxide?
Throw some copper wire into a fire. When it’s cool, scrape the oxide off the wire. Yes, there are two oxides of copper, a red oxide and a black oxide, and they both work well. We preferred the red, but I have no idea why.”
I originally planed to make this for the Crystal Radio / Fox Hole radio video I am working on. But while it technically works it is over complicated and not practical for the radio. But it sure was fun to make.