How to Make a Time-b, I mean, Timepiece
—or— Why People Who Get Scared About Things They Know Nothing About Make Me Want to Cry
Here’s a pretty standard radio alarm clock made by Timex. It does a few things and it does them well. It has a time display, which includes the date and indicators of what kinds of alarms have been set. It has two FM tuners and one AM tuner. These can also be turned on as an alarm clock. It also can play soothing sounds.
Here is it taken apart, 14 minutes later after I dug out my tools, disassembled, and laid it all out into position to photograph. No harm was done in the disassembling and reassembling of this device. What does it look like? If I brought this into a classroom, what would a teacher think? What would the kids think? What if I put it in a different case? What if I detached the piezoelectric buzzer and speaker and mounted all of it into a box so all the parts were on display?
Despite how it may look like to some people out there, it’s pretty harmless. It’s especially harmless since there are no explosives in it, nor would there be a way to set off explosives with it without making some extensive modifications. The worst part about it is plugging it in while it’s like this. If I touch the right part, it will hurt me (the part being the step-down transformer’s terminals and some of the capacitors’ terminals after the diodes acting as a rectifier).
Now, how do I know that? I know that because I’m familiar with the electronics inside of it. I wouldn’t have taken it apart and put it back together if I didn’t know I could handle what was inside of it. However, I wasn’t always that certain about electronics. I was just super curious and broke things. As a very young kid, I found my dads tools and snuck things like radios and clocks into my room and took them apart. When I first started doing this, I never could seem to put them back together again.
My dad worked repairing fire and security alarms at McClellan Air Force Base. This gave me two advantages. For one, he know enough about electronics so he could put things back together — if I had all the parts in tact. Two, he could also teach me about the innards themselves and about how electronics worked. He had also worked as an electrician. If I managed to blow a circuit breaker at home, he could show me how to fix it.
Eventually I learned about batteries, resistors, capacitors, inductors, diodes, and transistors. Then I went on to learn about Boolean logic and building digital circuits. This ranged from building simple one binary digit adders to clocks to the basics of building a computer. I learned about communication systems, too. How radios worked. How telephones worked. How the phone networks worked. How modems worked. It’s amazing what can be built from simple parts.
I used to take things I had taken apart to school. I had a bright yellow backpack that I used to stuff with electronics kits and other crazy things. Teachers must have seen a mess of wires sticking out of my bag at one point. This was Sacramento, CA in the 90s. It was before the 1993 bombing of the World Trade Center, but I continued to bring things to school even after that. I went to a private Christian (Seventh-day Adventist) school. I don’t know what impact that made on things, but no one seemed to be worried about me carrying around a bomb or parts for a bomb. Was it the era’s societal and cultural attitudes? Was it my whiteness and disarming smile? Was it the trusting and forgiving culture at the school? Was it the fact that my dad worked for the federal government? Probably all of those things. The important thing was that I hadn’t yet gotten into trouble (I did get into trouble years later, but the school dealt with me without the cops).
There’s, of course, the current tale of Ahmed Mohamed and his clock. He’s a 14 year old boy of Sudanese descent who happens to be an American kid and Muslim (why blame a kid for his religion?). His father happens to have run for presidency in Sudan, twice. Should any of that matter in this case? No, but it seems to have mattered. According to CNN, the teacher to whom he showed the clock was the one who felt threatened. Now, it might be arguable it was just the appearance of an eight inch wide metal pencil box with a time readout that caused the worry. I would say that’s an argument made out of ignorance and poor education regarding electronics. Given the circumstances, it would appear the whole context that caused the worry was:
Sudanese-American Muslim kid + cultures and religions are foreign and scary + weird McCarthyism like propaganda about Muslim beliefs + electronic parts on display + ignorance about common household items and how the are made = this must be a threat
This isn’t an isolated incident in that school district. There’s been plenty of other incidents that don’t turn out so well. Here’s a great blog post on the Irving school district turning kids into criminals.
There are other incidents of people feeling threatened by electronic devices they don’t understand. Take, for instance, the 2007 Boston bomb scare. Adult Swim wanted to advertise their Aqua Teen Hunger Force Colon Movie Film for Theaters with an awesome guerrilla marketing campaign. They had worked with an organization to build these electronic devices that, in the afternoon, turned on an image of one of the characters holding up a middle finger. The display was made of large LED pixels. People got scared. Police investigated. Since it was a company, no one was hurt. The investigators insisted the devices were similar to bombs: they had an “identifiable power source, a circuit board with exposed wiring, and electrical tape.”
There’s another recent crazy school related incident that has nothing to do with bombs. It is the case of a gifted sixth grader attending Bedford Middle School in Virginia and Japanese Maple leaf or something similar. He was charged with possession of marijuana and suspended from school for a year. He’s now attending another school with none of his old friends and has to be searched for drugs before and after school. The school maintains its strict policy where anything claimed to be a drug or is believed to be a drug, the student possessing the item in question is treated like it is a drug. No exceptions.
A Common Thread?
My first reaction to these instances is that it is just plain ignorance. Ignorance in policy making. Ignorance of other cultures. Ignorance of other religions and spiritualities. Ignorance of science education. It makes me want to remedy a few of those things, and I’ll try to do so.
The longer I think about it, the more I realize it has less to do with ignorance and more to do with beliefs. Once people are told something and believe that, it becomes difficult for that person to change their beliefs. If they learn certain falsehoods about other cultures and people, they will only propagate those beliefs and they most likely wont be convinced of anything else.
If they come to believe that electronics is difficult and over their head, they won’t want to learn anything about it. In fact they’ll be convinced they can’t learn anything about it. Unless they can be convinced that they are smart enough to learn it — and there are ways of doing that — they won’t be able to learn anything. If one gives them small victories, through small lessons and challenges, things will start to change.
If people are convinced that strict authoritarianism is the solution and proper disciplinary methodology, things won’t change. Things will remain terrible. Kids’ lives will continue to be ruined.
It is up to each of us to enable others to have these small learning victories. It is our job to let people learn that they can be curious and can easily learn new things. It’s up to us to take advantage of those “teachable moments” to make the world a better place, one small step at a time.
An eight inch pencil box with the guts of a store bought alarm clock is not infrastructure for a bomb. It’s cool looking to some people and frightening to others. It’s only frightening because it’s misunderstood. A misunderstanding is not something over which a kid’s life should be ruined.
How do we solve this problem? How will you begin to understand another very different person? How do we unite these fragmented states and communities of America, blown apart by the swift reaction of misunderstanding?
Now, to really understand the difference between a clock and a bomb, read on. I’ve written some simple descriptions. I’m sure it’s understandable to the layperson; if not all of it, most of it. Go ahead, read on, I’ll wait.
What Makes a Clock a Clock?
Figuring out what makes a clock is a fun task. So what is a clock? Is it a plate falling in water at a certain rate? Is it a certain number of grains of sand falling through an hour glass? Is it a pendulum swinging back and forth at a certain frequency? Is it a complicated set of springs gears weights and counter weights in a tiny wearable form? Is it a cesium atom?
At it’s most basic form a clock is a way of measuring time. It can take any number of forms from an hourglass to a sundial to an atomic clock. It doesn’t even have to tell one the time of day, but I think people have come to expect that from a clock.
I want to focus on the digital clock and how it’s made. A digital clock uses a power source to power all of its internal circuits. This power source can be either a battery or a wall plug that goes through a special circuit made to condition the power from the outlet for the rest of the innards in the clock.
The next most important part is a circuit that generates a signal that turns on and off at a specific rate. This signal is actually called a clock signal. The rate that it turns on and off is the clock frequency. Also long as this frequency is greater than one on/off cycle each second (1Hz), we can build a clock that displays hours, minutes, and seconds.
The part that comes after this is the counting circuits. These circuits normally feed into each other. A circuit will take the clock signal and convert it into a signal that turns on/off once per second. One circuit will take that signal and count seconds. Another circuit will count minutes. Yet another will count hours. Each time a seconds circuit counts to 59, it resets to 00 and passes a signal to the minutes circuit. The minutes circuit counts from 00 to 59, resetting to 00 each time and passing a signal to the hours circuit. The hours circuit counts the number of times the minutes reset to 00. It only goes from 01 to 12 and back again.
Each of these circuits hook up to another that takes the value of each counting circuit and maps it to a set of LEDs hooked up as seven segment displays for hours, minutes, and seconds. If I wanted to set the time on the clock, I would just have to adjust the value in each of the time counting circuits and they’ll start counting from that time. If the power is removed, it’ll reset all the circuits to 00. Which means 12 for the hours most of the time — this is why a VCR (oh, I mean DVD player) and digital clock radio will start flashing 12:00am when the power goes out.
What about adding an alarm to the clock? That’s pretty simple. Just add another set of circuits that hold the hour, minute, and second values to set the alarm. Add another circuit that compares those values to see if they’re the same. When they are the same make it send a signal to another circuit that switches power on to a piezoelectric buzzer circuit until a button is pushed to turn it off.
Of course that piezoelectric buzzer circuit could actually be anything. It could be a sprinkler system. It could be a light. It could be a motor. It could be a — use a wild imagination, just don’t get diabolical. Many of the same circuits used to build a digital alarm clock are the same circuits used for building processors and many other systems we all count on.
What Makes a Bomb a Bomb?
Disclaimer: I don’t condone building bombs. You’ll probably blow yourself up before anyone else. In many cases the explosives needed are also illegal to transport or take off your property (or make in a rental unit) unless one has a Federal Explosives License (and permission from all landowners involved — which isn’t going to happen in an apartment complex). If you want to learn more about potential threats and what they could look like (including how much they would weigh), take a look at the National Counter Terrorism Center website. Please also realize that terrorist attacks in the US are near nonexistent, so don’t be alarmist like the folks at the Irving, TX school. Let the professionals do their thing. Don’t try this at home. Respect the forces of nature. Don’t be a jerk. Etc.
Explosives go boom! Explosives are interesting technologies. We couldn’t have made the freeway system we have without them. Most demolitions couldn’t happen with them. We also wouldn’t have Mount Rushmore without explosives. We also wouldn’t have some crazy movie stunts or special effects without them. We also couldn’t mount the wars for which we seem to have so much of a penchant if we didn’t have explosives. Not to mention, society probably wouldn’t have any gasoline or advanced electronic devices without the explosives used in mining.
Some explosives are very unstable and other are more stable. When I say unstable, I mean that it takes very little energy to make it explode. Nitrogen triiodide is a perfect example of this, because it explodes as soon as it is touched (see video above). Stable explosives would be something like commercial TNT. It can be touched and handled without setting it off, so long as the right procedures are followed.
Fireworks are technically explosives — they’re just not very powerful ones (though they are still very dangerous). What makes an explosive powerful? An explosion, just like a fire, is a chemical reaction where a lot of heat is released. There is also a lot of pressure generated. Just like a fire, it takes something to start an explosion. Typically, this is something like a fuse, igniter, or a detonator. These can be chemical, mechanical, or they can be electrical.
Let’s say someone is building a bonfire and they want to make it huge. They’ll start with a small amount of wood, and will gradually add larger pieces to it in order to keep it going and make it larger. The same sort of thing is true for explosives. The amount of explosive needed is directly related to how large the explosion will be. Other factors impact the size and types of damage done: how directional the blast is, how much energy was used to start the explosion, etc.
A fairly common explosive use is in guns. Most police officers carry around a gun that has a bunch of bullets in it. A bullet is a projectile lodged in a casing loaded with gunpowder (an explosive). The casing also has a special type of contact explosive in the back of it, this is called a primer. Someone pulling a gun’s trigger releases a spring loaded “hammer” that hits the primer. This creates a release of heat and builds pressure inside the chamber of the shell (casing), this causes the gunpowder to explode directionally. Sometimes it is just the gunpowder that acts as the propellant. Other times, it is the pressure wave of the explosion in the chamber which launches the bullet through the barrel, sometimes at a speed faster than sound itself.
Something that is explosive has the the power to compress the air around it so much that this forms a pressure wave so intense it’s called a shockwave. This shockwave can destroy things in its wake. One of the most impressive demonstrations of this shockwave has to be the nuclear bomb test footage. One can see dirt rising off the ground and then the entire structure get pushed one way for a few seconds then pushed and twisted in the other direction as the air pressure returns to normal. The process of the air pressure lowering is called rarefaction — the opposite of compression. Things closest to the center of the explosion will be damaged the most. This is partly from the intensity of the pressure and partly from the intense heat. In the case of a nuclear explosion, the radiation also causes intense damage.
An explosive device of any size is concerning to have in a public space. It can hurt people. It should be reported. The problem of course, is knowing what is explosive and what isn’t. I think that people should be more concerned about a large backpack or suitcase laying around than an eight inch box with electronics in it.
Turning a Digital Alarm Clock into a Trigger Device is Insane
Lets say I wanted to turn my alarm clock into a model rocket launcher. I’ll make it launch the rocket when the buzzer goes off. I’d need to make a circuit that can take the buzzer’s signal and turn on a digital switch (debouncer + toggle flip-flop + power transistor) which would allow a power source’s energy to flow through the model rocket igniter, burning a small wire igniting the material around the wire. This of course, will launch the rocket — which is basically a controlled explosion.
I’d also need a much larger battery in order to set off the rocket igniter. It’s two AAA batteries would most likely not be enough, unless I used another component like a capacitor to store an electric charge big enough. However, that’s probably not feasible. It might not be able to store enough of a charge soon enough — so it is either more batteries or a larger battery.
Why is this stupid? Most clocks have small glitches in them once the piezoelectric element is switched out and sometimes even as is. Most of the time, one wouldn’t hear this. I’ve done several modifications to alarm clocks and every time, I either had to figure out how to filter the random pops, hisses, and other noise before my modifications could use the signal; or I would just live with it. The work around introduced more complexity and more circuitry, without which it would randomly turn on whatever was attached (or make a clicking sound through my stereo amplifier). So if I wasn’t careful with setting up my model rocket launcher, it could easily ignite the engine way before I wanted it to launch. It shouldn’t be too difficult to determine why this is a terrible idea.
Sure, anyone can claim that a clock is really infrastructure for a bomb. It can also be argued that it is infrastructure for a large, cobbled-together computer. The reality is that no one is going to use an unsophisticated and unreliable control like that unless it’s a screenplay’s plot or they really don’t care about the outcome. If they don’t care, something would probably happen without warning. It’s equally possible they would also just be sloppy and get caught before anything happens.
Originally published at jburrows.wordpress.com on September 21, 2015.