Popular Crystal Radio Design That’s a Waste of Time – And Why (Updated Video Available)


I have been trying different crystal radio designs, experimenting with crystal radios lately and I decided to put together something that would allow me to build these designs quickly and easily using jumper wires so I could test these designs because frankly I have found a couple designs that do not really work very well and so I am going to go through some of the popular designs on the Internet and see how well they really work. This setup will allow me to put them together quickly to show you what’s going on you and wheter they work or not. The first one is a very popular design it’s got a variable capacitor tuner Let me set it up and we’ll see how well it works. We can compare it to this design which is the modified boy scout radio and we can compare the two and see which works better OK, let’s get started This is the setup, from our picture you can see, we will check it, the antenna goes through the coil to the ground. We have the antenna connect on to the capacitor antenna comes through here connects also to the coil this is tapped to the coil right here and
a then goes across 80 turns, 20, 40, 60, 80 turns. 80 turns later goes to the ground which is this yellow wire following colors: connect back here to
the and they also connect to ground, you can see ground connects to the variable capacitor. The diode on the antenna side here Comes through the insulator block down here, connects here to 1 side of the crystal earphone. The other side of the crystal earphone goes back to ground okay we got that covered. Now you listen while I tune through this and you can hear what we get. >All I get is 1 station when I listen. I have gotten up to 2 stations but this is only 1. This is one of the most popular designs This design you’ll find all over the internet, it looks very good but it plane doesn’t work. I have tried many different configurations, using other coils and other numbers of turns and so forth, other variable capacitors, bigger and smaller and I get one or two stations at most so it not working like I thought it would. I thought it would work like a transistor radio, I’d be able to tune the variable capacitor and I would get all the different
stations and very clearly and I’ve never have. Let me go through a little bit why I think there’s a huge
difference between this and some other crystal radio designs that work better for example those with the wiper on
them. OK, let’s go over that the you agree with me Here’s my theory on why these 2 crystals operate very differently, why this one will receive… I’ve gotten 17 to twenty
different stations on this one and this one I get 1 or 2. Why is that? My theory is, if we look at these, If I take any coil, it has both induction and capacitance and that’s what creates that resonance thing and gives you the radio tuning and what the wiper is doing is dividing the coil in 2 different parts The left side has inductance and capacitance and the right side has its own separate inductance and capacitance. As I move this wiper the inductance on this side is getting smaller and on this side it’s getting bigger And when I move it back this way the inductance and capacitance on this side is getting bigger, hugely bigger and on this side it is getting much smaller and I’m changing the inductance and
capacitance together so I’m getting this huge change in inductance and capacitance which again is what causes that resonance thing thing in the circuit which give me the
radio On this side, I got the first 80 turns like they told me they told me, I got it tapped here I got the antenna here and the first 80 turns, like they told me Here’s the diagram. 80 turns and that’s it There’s nothing else, no wiper on
there. I’ve got 80 turns and I’ve got the inductance and capacitance from those turns and that it. and then I’m just changing the capacitance in the variable capacitor across here, which is right here and i’m changing the capacitance, BUT, all of this is fixed there’s no induction or capacitance changing here, so I’m only going from about 0 to 360 pF and again no
change in inductance My guess is that’s why this one picks up 1 station, and frankly I can get 1 station with a diode, antenna and ground So I don’t need all this stuff. My guess is again that’s why this setup does not work nearly as well as this setup because the I’m only changing a little bit of capacitance and the inductance and capacitance in the coil stays fixed. Where on this side i change 2 So I get a whole different change in the set of inductances and capacitances, the left set and the right set That is my idea why this modified boy scout radio works much better and this diagram that you find all over the internet I’m disappointed because I wonder how many people have given up on crystal radio because they try to do this and it just doesn’t
work That’s it for this setup. I mean this plain doesn’t work very well and I would discourage people from trying it. I’m not the only one who posted on the internet that this thing doesn’t work well but hopefully people will see this style and build it and have a lot more success with it. That was it. Hope you found it interesting and useful in your crystal radio building

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