[Build-A-Lot 4: Power Source Full Crack [Torrent]
Rancul Ratha
There's a lot that goes into making a nice crystal radio set, so this is going to have to be broken down into two parts. The first part is the actual making of a functional radio, and the second part is making the whole arrangement look nice. In this part, I'm actually going to tell you more than just how to make a crystal radio, but I'm also going to explain how and why they work.
Crystal radios are pretty Steampunk in and of themselves, since they were first developed in the late 19th century. The technology was discovered in 1874, though it wasn't put into commercial use until the very early 20th century. The great thing about a crystal radio is that it doesn't need a separate power source, since all the power it needs is picked up from the antenna. As a result, most simple sets are pretty low-volume, but they still work just fine!
For those of you who aren't tech-savvy, this project is really, really easy. Anyone can do it, provided that you have the right parts. Here are all the parts you need to make a crystal radio, and I'll explain what they are, how they work, and where to get them:
With a crystal set, it's important to have an antenna. Your coil (which I'll be talking about later) can function as sort of an ad-hoc antenna, but for the best results, you need a good antenna. The reason you need a good antenna is because the more antenna you have, the more power your set will receive, and the louder it will be.
Some of you may be familiar with Nikola Tesla's experiments in providing the world with wireless power. Well, "power" can mean a lot of different things. We often think of electricity as water, flowing out of our electrical sockets as needed. In reality, it's a lot more complicated than that, and like water, electricity has waves, currents, and other characteristics that govern its various attributes.
While you may think of radio waves and electricity as being different, they're actually the same phenomenon! Radio waves are just fluctuations in the electromagnetic fields that surround us at all times. Think of the waves in the ocean: they can push you around because each wave has its own kinetic force. Well, you can kind of think of radio waves like invisible ocean waves. They're invisible to us, because they don't react with us. However, a copper wire can "see" the waves because it's a conductor of electricity!
You can essentially think of the waves as vibrations. When they hit a conductor, they make the conductor vibrate. In this case, the vibrations are so small that they're almost impossible to hear. That's why you need a crystal (or diode) to adjust the signal, and then a very, very sensitive earpiece to hear it. When you use a powered radio, it adds that power to the circuit, amplifying the vibrations until they become quite loud. That's what the battery (or plug) does. No matter what kind of radio you have, it's always picking up the radio waves, even when the power is off. You just can't hear them unless you're amplifying the circuit because of the way modern radios are built.
Well, that's a hard question to answer, because each type of wire has plusses and minuses. Generally you'll be dealing with two different types when it comes to crystal radios, insulated wire and magnet wire. For all intents and purposes on this project, insulated wire and magnet wire are the same thing. It doesn't matter which you use, though you can see in the picture below that I used magnet wire.
You're going to need to pick a wire gauge, and that will affect your tuning ability. I went with a 16 gauge for mine, but I recommend slightly smaller, as that may be easier to work with. So maybe go with an 18 or 20 gauge, but it's largely a matter of whether you prefer to work with a larger or smaller wire. We can adjust the tuning ability later, based on what gauge of wire you go with.
When I first set out to make a Steampunk crystal radio set, I thought to myself, "Yes! I will find a real crystal for my radio, and it will be super authentic and awesome-looking!" That enthusiasm died out pretty quickly, unfortunately, as I came to learn exactly what was entailed in using a real crystal.
The crystals you can use for a crystal radio are pretty limited, and it's not like you can just hook it up to a piece of quartz. Most of the crystals that are useful for a radio aren't ones that look particularly pretty, such as galena, which is a crystal form of lead.
Second, tuning them is a gigantic pain in the rear. A crystal radio that uses a real crystal is called a "cat's whisker" set, because of the way that the wire dangles over the crystal. Essentially, you need to constantly hand-tune them while you're listening, or else you'll lose the signal. It's terrible.
So despite my earnest desire for authenticity, I had to compromise for the sake of not pulling my hair out and just use a modern diode. "Modern" is of course a matter of perspective, as the design of the modern diode hasn't changed significantly since 1930. While I could potentially have used a vacuum-tube diode, they're much harder to come by and still slightly past the Steampunk era. I may continue to look for one, though.
When you have a circuit, the signal will flow anywhere it can, even backwards. If your signal is flowing both forwards and backwards, you're going to get a giant mishmash of signals if you try to listen to it. They'll cancel themselves out, and do all kinds of things, making it unlistenable. In order to fix that problem, you use a diode to filter your signal on the circuit. That way, you only receive one version of the signal at your earpiece.
If you want to think of it like our water analogy from earlier, think of a circuit as a pool. The water is everywhere in the pool at once, just like the electricity in a circuit. If you throw a stone in the pool, the ripples will flow outward, and if you had a way to measure the waves at the edge of the pool, you would get an unimpeded signal from the waves you made. Now, imagine if you threw two stones in the water at the same time, at opposite ends of the pool. The ripples will meet in the middle and cancel themselves out, making the whole pool kind of wavy, but destroying the purity of either signal. The normal state of a circuit is like the two-stone model, but adding a diode turns it into a one-stone model, allowing a pure signal to be measured at the end.
In order to actually hear the signal, you need a special type of earphone; the ones you have sitting around your house just won't do. That's because modern headphones are designed to use power, far more power than you can pick up with a reasonably-sized antenna.
Since you have very, very little power coming down your line, you're going to need an extremely sensitive earphone that will react to the tiny vibrations in your circuit. This is called a "high impedance" earphone, or a "ceramic" earphone.
Unfortunately, only one type of high impedance earphone is still being made in the entire world, and it's terribly ugly. There are a variety of places you can buy them from, but I did some research and discovered that they all come from the same factory in the UK. Even more unfortunately, they're crap. The quality is just plain awful, because some just flatly won't work and other die in short order. And what's more, the manufacturer knows it, and refuses to do anything about it. Nice, right? However, if you want to buy a new high impedance earphone, you're stuck because they're the only sellers.
It comes with a normal 3.5 mm jack at the end of it, but for a crystal radio, you'll want to cut that off and expose the two wires at the end. It's only one earpiece, but you need two wires in order to complete the circuit properly. We'll get into that a little more specifically below.
A resistor is something that lets you manage the amount of power you have on a circuit. Without getting into technical things like current and resistance, it basically lets a certain amount of power through it, so that anything attached to the circuit doesn't get overwhelmed. With a basic crystal radio, you may not need a resistor. However, if your antenna is long enough, you may pick up enough power to blow your diode, which you don't want to happen.
It's a 47k resistor, which is... well, rather complicated to explain without getting really technical. To be as simple as I can get, this resistor provides 47,000 Ohms of resistance to the circuit. Resistance helps control the current of the electricity. This is the shallow end of a very, very deep pool, so I think I'll just leave it at that.
What you need to know for this project is that if you're going to have a long antenna, you should include a 47k resistor. They're available for sale through pretty much any electronics store, and you can even order them on Amazon or Ebay.
The first step is to make yourself a coil. Coils are exceptionally easy to make. All you have to do is get something that's non-conductive (plastic, wood, cardboard, etc.) and wrap some wire around it. You want to leave the insulation on, which in the case of regular wire will be plastic, but in the case of magnet wire will be enamel. It will also work better the tighter the coil is, but it will still work with a loose coil.
Ideally, your coil form will be something that's between 4-6 inches in diameter, and hollow. The less material there is between the wires, the stronger the magnetic field they generate will be. The form doesn't even need to be round... A square or rectangle one will work just fine. In fact, for my first crystal radio, I used an empty cardboard box:
Now, I used a few things that you don't really need for a bare-bones set. First, I had a spare piece of wood lying around that I used as a base. You don't really need that. Second, I had some little metal clips that I used for ease of assembly, but you don't need those, either. Lastly, I had a little alligator clip, but that's not necessary either. The alligator clip may make life a little easier for you, though.
Anyway, what you want to do is wrap your wire around your coil form. Every three turns, make what they call a "tap". Taps are those little loops of wire you see in the picture above. You just take some extra slack and turn your wire into a loop. Do that once every three turns, and do a total of about 40 turns. That means you should end up with 13 taps.
795a8134c1