0:159 on the 69th day of Winter

It took me less than a day to put together a basic prototype radio. I would have been faster but the other crafters took priority on the equipment for their projects. I didn't mind. The radio was built into a cube shaped crystal which connected to a quarter wave whip antenna. Amplitude modulation, or AM, radio is super simple in principle. There is a carrier wave that the device puts out all the time at around a megahertz. That is then multiplied by the actual sound waves you want to send. Human hearing is in the twenty hertz to twenty kilohertz range so that tends to look very slow compared to the carrier wave. To recover the voice signal at the receiving end you just multiply it by the carrier signal again and then run it through a filter to get rid of anything above twenty kilohertz. Signal filters are like a car's suspension, the high frequency vibrations of the road are absorbed in the springs so that the driver only feels the big bumps. In a circuit, capacitors are like the shock absorbers and inductors are like the mass of the car making it hard to move.

The hard part is making electronics that can multiply signals and filter them without distorting them too badly. I had cobbled something together with transistors but it wasn't working very well. Especially the phase locked loop, or PLL, I had put it together with the circuit equivalent of bailing wire and duct tape. Basically, a PLL is a complicated set of electronics that recreates the carrier signal, and critically its exact timing, within the receiver circuit. AM radio stations got around needing them by actually putting out two identical carrier signals, offset by just a microsecond or so. Of course that meant they relied on massive radio towers and it cut their effective range by a factor of four. In my portable radios, the PLL would increase range, reduce power consumption, and actually make a clearer signal overall. If I could get it to work.

What I really needed was an op-amp. Op-amps are a type of integrated circuit that has about twenty transistors built into it, along with a bunch of resistors and capacitors. Basically, it takes two inputs and a power supply to turn a voltage signal into an amplified current signal with very little distortion or instability. They made electronics a lot simpler to design as they could multiply, divide, add, subtract and even filter signals very easily. I was currently debating if it would be better to reinvent them or to simply make a radio that only worked with pulses like Morse Code.

I was given three days to show progress so I was currently procrastinating by doing some thinking on another project. As I used my magic again and again to make the parts for the radio I gradually forgot about the horror of the method I was using to control it. Then I would remember and almost get sick again, but I was making progress. It made me feel that I was overthinking things. Mages controlled their magic. It worked. It had worked for hundreds of years. It wasn't rational to freak out about it. It was like realizing the sun is a sustained nuclear fireball and freaking out every time you see it. I needed to calm down and think of how I might use this knowledge.

The first thing I could do with it was to make my lasers safer with a ranged darkness effect. If my hypothesis was correct then I could engineer a device that would first look at its target and make sure that it was absorbing all light. Then, shooting a laser at the target would be safer because none of that light would reflect off to blind people. At least that's how Arin described her spell. So I started with a precision, directional light sensor in the form of a small cylinder. The sensor used vertical nanotubes spaced far enough apart for light to pass in a straight line to look at a spot ahead of it and about a millimeter across. I built a reflective metal box that kept out all the light and mounted the device in the middle. Then I made a remote controlled light marble and placed it in the box with the sensor.

I put a low powered laser behind a one-way mirror that allowed the sensor to look at exactly where the laser was pointed. Then I got to the dangerous part. I took out a light magic core and very carefully wired the output of the sensor to the input graphene threads that would trigger the end-of-the-world button. This way, if the sensor received light the world would be destroyed. However, in some very small fraction of the wave function, the material would absorb most of the light from the laser. I, and everyone else in the world, would only live to see it if this improbable outcome actually happens. So, our only experience of reality would be a reality where it worked. Yeah, this was so dangerous.

"What are you doing?" asked someone behind me. Startled, I jumped half out of my chair and looked around. Irmingar was looking curiously at the box from over my shoulder.

"Nothing special." I said with a cough, trying to act natural.

"That's a really strange light spell." he said pointing to the low powered laser dot. "It has almost no scattering. Is this what you're using in the signalers?"

As my heart slowed back down I considered his question.

"No, this is a side project." I said. "I am trying to decide how to proceed on the signalers and this is helping me clear my head."

"Oh? What are you deciding on? Maybe I can help." he said.

Maybe talking it out would help me make up my mind. "Well, my design works in principle but there are a couple of ways to make it work in practice." I said. "The first way would be something I could make work quickly but probably wouldn't quite as well. It would meet all the requirements but it would take people time to learn and get good at. The second way would take me longer to put together, but would be much more intuitive. I imagine it would be immediately useful in the field."

You could be reading stolen content. Head to the original site for the genuine story.

Irmingar thought about it for a bit.

"Are there any other trade-offs?" he asked.

"Maybe…" I said, considering the question. "The first one would have a longer maximum range. The second would transmit information more quickly."

Speaking words into a radio could communicate information extremely quickly.

"Take the extra time to go with the second option." he said. "At least as far as I understand it, even if you have something that meets the requirements tomorrow, it wouldn't really be useful to the war effort. I have to say, it makes me really curious to see what you're working on."

"Thank you," I said. "That actually helps. I will go with the second method."

At his expectant look I rolled my eyes.

"No, you told me to do it right so you will have to wait for a demonstration." I said.

"Fine, fine." he said. "Remember though, I've been working on this project for a season already. We couldn't make it work because of how much it would cost. Don't go trying to add features until you have something that works."

With his peace said, he left and I got back to work. I was starting to have fun again.

***

1:099 on the 71st day of Winter

I settled into a grueling routine in my new workshop. Eating, sleeping, and working were my only pastimes. What Irmingar had said, about being useful in the war effort, had really stuck with me. Even one radio could make a big difference. So, I worked.

This morning, or was it late last night, whatever, I finally got the op-amp working right. The circuit has three main elements that make it work: the differential amplifier, the voltage amplifier, and lastly the output current amplifier. Noise is a big problem in most circuits. If you just amplify a signal then most of the time you are amplifying the noise right along with it. The differential amp gets rid of noise that shows up on both of its inputs to make a cleaner signal. The voltage amp is the high gain part that really boosts the signal and that, in turn, drives the current amp. The current amp is the output because current is useful for actually driving other electronics. You want to make a light turn on, or get a switch to flip, you need current.

That long winded explanation is to say that today I could start building the amplifier and filter circuits that would make the whole thing work. But before that, I was taking a break to work on my side project again. I had earned a break after all.

I set up my first test of the ranged darkness effect carefully, double and triple checking everything. The low powered laser was on and ready, the light sensor was tracking it, and the light magic core was primed and ready. I held my breath and pushed the button. I saw the laser light dim to nothing and there was even a small dark spot where it was before. Success!

Next I built a basic copper-iron thermocouple temperature sensor with a test end and a control end that I put under the desk. Well, I actually used a roughly equal mix of copper and nickel to make a standard J-type thermocouple because I vaguely remember that the curve is about half a volt for every ten degrees Celsius. I put it on a metal stand in the middle of the dark spot and recorded the voltage. Sure enough it read zero volts meaning it was the same temperature as the ambient air. Then I turned up the power to the laser. After waiting a bit I checked again. Still zero volts.

Scratching my head I tried to think of why it wasn't working. My laser was probably still too weak. I replaced my laser with one I knew would put out about 10 watts of light. My sensor was small enough that it should cause the temperature to shoot up about somewhere between 20 and 40 degrees C per mark. I ran the test again pushing the button for about ten marks. There is something. The sensor read 0.564 volts, meaning it was about ten or maybe twelve degrees hotter than the air in the room. I decided to run the test again but this time with the core disconnected. I closed the box for safety and pushed the button for another ten marks. Now the voltage read 10.879 volts meaning the sensor was somewhere north of 200 C hotter than the room. Okay, that meant that the core was reducing the strength of the laser.

Thinking about the problem for a bit I realized why. The only thing the core was doing was removing any parts of the wave function where the sensor saw some amount of light in front of it. What was left was some combination of all the factors that would have that result. Part of that was the darkness spell on the object itself. Some more light blocking would come from the air becoming slightly opaque. Lastly, and most critically, a lot of the light reduction could come from the laser being less efficient, converting less input energy into light and more into heat. I needed a way to also cut out that part of the wave function. I can do that. I took another look at the one way mirror that I was using for the light sensor. It was a diamond lens with a convex surface that I coated with a few atoms thick layer of polished titanium. This meant that the laser was seeing about one percent of the light coming back while 99.999 percent of the light from the laser passed through. The remaining light was absorbed by the titanium which meant that it would heat up quickly. I decided to do this exact thing in reverse, coating the other side of the lens but only sparsely this time with tungsten. This should deflect even less of the light to another sensor that I would then tune to drive up the efficiency of the laser.

After setting everything up I turned on the ten watt laser. Then I started to dial up the efficiency by triggering the end-of-the-world button any time it was below a threshold. Up and up it went. I switched out thermocouples a few times to make sure they were measuring the heat generation correctly. Twenty watts, thirty watts, forty watts. Just past fifty watts the circuit broke. Okay, so I can get four times as much power out of the same hardware with this. This should also mean that the lasers generate one fourth as much heat as well which is fantastic. I reconnected the darkness spell circuit and pressed the button. After a bit of fiddling I managed to get a full forty watts with no visible sign. I even noticed a dark line cutting through the air from the laser to the target. That was it! I had done it!

I stood up and looked around the workshop. I wanted there to be someone there to celebrate with me, but alas, nobody was there. I had worked late into the night again and everyone was at home asleep. Oh well, I would tell Schrodinger when I got home. Before that I had one more thing to do. I took the laser rods out of their holsters and placed them on the desk. I needed to scale up my prototype to make it work on the full power versions. If I could get three or four kilowatts from each of these lasers, with the material absorbing almost all of the light, these would become truly deadly weapons. Even the armored kith couldn't shrug off a hit like that. Best of all, I wouldn't hurt bystanders by using them in combat.