All too often, the commentors here on Hackaday display some parsimony in their engineering prowess. If someone uses a Raspberry Pi to blink a few LEDs, someone will invariably chime in that an ARM microcontroller would do just as well. Switching a relay on and off belies the capabilities of a 32-bit Cortex microcontroller when a simpler 8-bit build would certainly suffice. Of course this can always be reduced to a 555 circuit and further still to conditioned pigeons tapping a key in response to either food or opiates. I’d like to take this opportunity to present a tutorial. Not just any tutorial, but the actual foundation of everything we love here at Hackaday: blinky, glowey things.
You can check out the rest of this tutorial after the break.
Put bluntly, every project dealing with electricity needs a power source. Whether through mains power, a solar cell, some sort of strange inductive contraption, or through a chemical reaction, every electronic project needs a power source. I have considered a few different power sources for this project including mains power (far too dangerous to use with a light bulb), a bicycle generator (I’m focusing on strength training this week. Cardio is next week), hamsters and wheels (burning the hamsters as a fuel source and using a heat exchanger to turn a turbine), and magnets (how do they work?). In the end, I settled on using a battery to power the light bulb for this project.
The battery used for this build. It consists of four ‘D’ cells connected together in series via a COMF UM-1×4 battery holder. It provides 6 Volts across its terminals.
The power source for this project is called a battery, as it is made up of a collection of cells. [Benjamin Franklin] came up with this terminology, alluding to artillery formations. Just as more than one cannon is needed to form an artillery battery, more than one cell is needed to form one electronic battery. Yes, this means the AA, AAA, C, and D cells are not batteries per se, but individual cells. They only become batteries when used together. One exception of this is a 9 Volt battery, itself made of eight AAAA (that’s quadruple-A) cells. Seriously. go take a pair of pliers to a 9 Volt battery and see for yourself.
For this project I’ve used ‘D’ cells, as they have a larger capacity than AAA, AA, and C cells. The longer life of D cells is vitally important for this project; I very much expect to have this project sit in the back of my closet or tucked away in some drawer for quite a while until I stumble across it one day and remember the beautiful April morning where I wrote this tutorial fueled by at least two pots of coffee.
Of course just simply putting a battery next to a light bulb won’t do any good. Unfortunately transmission line theory is far too broad a subject to cover in this short tutorial so I’ll just have to cover the basics right now. This battery has two leads coming out of it; a positive and a negative. If we connect the positive wire to the negative wire, electricity will flow through the gap. At higher voltages, a small spark may form. With the voltages we’re working with here, it’s fairly safe, although it is possible to electrocute yourself with even these small voltages. While this may only be possible by stabbing your heart with electrodes and applying power, safety is of utmost concern when playing with electricity.
The light bulb
As connecting the positive and negative terminals of a battery together is amazingly stupid, we might as well throw in a light bulb. For this build, I’m using a 6 Volt light bulb that pairs perfectly with our four D cell battery. Just like our battery holder, the socket for the light bulb is attached to a piece of plywood, much more convenient and ergonomic than any flashlight or electric lantern.
You may notice the light bulb is off in the picture below. This is because the light bulb is not screwed down completely into the socket. Yes, unlike LEDs where electrical contacts are soldered on, light bulbs are usually wired into a circuit with a screw-type base. Just as with the lid on a jar of peanut butter, you screw the light bulb into the socket by turning it clockwise. To remove the light bulb from the peanut butter, unscrew it by turning it counter-clockwise.
Before we get into the actual process of turning on a light bulb by screwing it into its base, let’s first consider how a light bulb works. The light bulb was invented by [Thomas Edison] after many, many failed attempts at creating a practical electric light. The light bulb I’m using passes electrical current through a tungsten filament, heating it up and producing light as blackbody radiation. Before discovering tungsten as a perfect filament for an electric light, [Edison] tried hundreds of different materials from carbonized bamboo to the hopes and dreams of a young [Nikola Tesla]. Of course the use of tungsten wasn’t without its downsides – at the time there was no commercial use for tungsten and its extremely high melting point, the highest of any element, made it impractical for use in industry.
[Edison]‘s use of tungsten in his successful light bulb guaranteed the continued employment of thousands of tungsten miners in backwoods West Virginia tungsten towns. Life there wasn’t easy, sellin’ your soul to the company store and watchin’ your son grow up to take your job after you’re lost to a tragic cave-in. Of course working conditions improved after the tungsten miner riots of 1824 and the intervention of governor Batman.
In closing, The Professor on Gilligan’s Island was an incompetent fool. As he was clearly not a materials scientist or structural engineer vis-à-vis his inability to fix a hole in a boat, we can only assume he was some sort of physicist or electrical engineer. This is not congruent with The Professor’s actions, though; even a second year EE undergraduate would be able to construct a simple spark gap transmitter using components found in their radio and wiring found aboard the ship.
“Oh, wait.” you say, “broadband transmissions and thus spark gap transmitters are illegal.” Yes, well that’s kind of the point. I guarantee that if The Professor built a spark gap transmitter – and remember, this is the simplest transmitter that can be made out of coconuts and possibly one of Mrs. Howe’s evening gowns – an amateur radio operator would have tracked them down within a few hours. We already know The Professor knew Morse from the season two episode, Ghost a Go-Go, so really there’s nothing stopping the Professor and everyone else getting off the island.