crystal radio: the first real free energy device

[TinselKoala]

A good earth ground is best. Your earth battery carbon ground probably will work fine. If you have metal conduits in your home, the outlet coverplate screw might work OK too. The better the ground the better performance you'll get, just like with antenna. The Slinky is a compromise. For the very best performance you'd want an elevated "long wire" antenna in an "L" shape with the lead-in wire connected at the junction of the two straight legs, and a ground that is a copper pipe driven 4 feet into moist soil or something like that. The antenna lead-in should be insulated from contact with stuff like the house frame, etc.
But you can get acceptable performance with other arrangements, like the Slinky and more casual grounds if the stations are strong or nearby.

[Pirate88179]

TK:

Thank you.  I figured that this might be the case.  I suppose I should have made one of these when I was a kid but...it's never too late...right?

Do you get better long distance reception at night with the ionosphere skip?  (or whatever it is called)  No matter what happens, this is a really fun project that will help me learn more of the basics.

Weather here is bad and I saw at lunch on TV video of snow in TX!!!  I just got home and we have sleet/freezing rain turning to snow later with a low of 15 F.  I will most likely be snowed in..again but, we will see.

If we have a blackout from the storm, can I run my heat pump from my crystal radio?  (Just kidding)

Thanks,

Bill

[pomodoro]

Here are some Current vs Voltage curves of my collection of galena.  Homemade synthetic galena is compared to natural galena and a germanium point contact diode.  The synthetic galena is at the moment not as good as one of the natural samples, although in a crystal radio circuit it gives good audio volume and nearly as current into a load. Compared to a germanium point contact diode, galena is not as good. Although not shown in the graphs, the forward drop is about the same as germanium, but the downside of galena is that it conducts too well in the reverse direction, especially when the voltage gets high enough.  This is not a problem in a crystal radio, since the antenna voltage is quite low, and the galena works just as well as germanium. As you can see, some of the sample start conducting in the reverse direction just below 0V and these samples give less audio volume, as the reverse current ' cancels out 'the audio from the positive side of the radio wave. I'd like to improve the quality of the synthetic galena before doping with the uranium.

[profitis]

Nice pomodoro.it would be interesting to see how well pyrites can get catch a signal as compared to galena.I hear MnO2 (pyrolusite) samples also have good ability to catch a radiowave.

[pomodoro]

I need to brush up on semiconductors. Here are some questions:
1. PbS( a lump not in a diode configuration) is an insulator until a critical voltage (band gap) is applied, then it becomes a conductor. Correct?

2. The catwisker acts as the p type semiconductor, creating the diode with the n type galena?

3. How is the p type formed, is it an oxide on the metal? It can't be pure metal only correct?

4. Why is a fine point needed, as a thick wire turns the diode into  a normal conductor?

5. Why does some galena conduct well both ways with the same catwisker that works well on another sample.