Low-Budget Electronics Projects For High School? 364
SciGuy writes "I am a physics teacher for 9th graders. I really want to teach them modern electronics (something beyond the light bulb and battery). My hope is for a project that: 1) Is fun 2) Teaches about circuits that are relevant to their life. 3) Doesn't rely too heavily on a black box microcontroller. Individual components would probably be better. (I realize that #2 and #3 are probably contradictory. They will already be programming in my class but I want them to understand the circuitry behind modern tech.) 4) It must be as cheap as possible. Yay, public school. Unless some of the parts can be scrounged or found at home, I would probably want to keep the project around $5." What would you build?
Oscillator? (Score:3, Insightful)
Re:Good Luck (Score:1, Insightful)
Soldering has no place in a public school. 1) Someone will burn themself, and sue. 2) Someone will sue because of exposure to hazardous materials, or some government agency will get involved.
Besides, soldering assumes you have PC boards to solder to. Solderless breadboards are easier and safer, as long as you stick with thru-hole components.
Cost effective? (Score:5, Insightful)
$5 won't buy you much if you buy the components individually. You need to buy them in lots -- in which case you can afford a lot more room to experiment. Also, some equipment can be re-used, like breadboards, multi-meters, etc. When considering the project's costs, don't neglect economy of scale. It might be cheaper for everyone to simply have a "lab fee" and buy enough to last a few years.
Re:Do they still Sell 100-in-1 kits? (Score:5, Insightful)
B.S. Evolution doesn't happen on timescales of 20 years (I'm only 31). Kids aren't any smarter, dumber, or less or more inquisitive, except to the extent that no one has lit their imaginations on fire yet. But, it sounds like this teacher at least wants to *try*. More power to him, and I hope he finds something which fits his classroom needs.
Truly smart, creative engineers and scientists don't need to find jobs - they *create* jobs (often, not only jobs for themselves but good paying jobs for many other people). So, I'm not too worried about America's future, as long as we actually *try* to educate and excite kids about science and engineering.
Keep it simple and relevant to course material (Score:1, Insightful)
You're going to have a tough time building anything practical for a $5 budget. I'm going to assume you mean $5 per student with a class of around 30 - you can't usually buy resistors or the like in quantities of "1", and just a (decent) breadboard can't be had for less than $5 unless you're buying in bulk. It would be best to have each student (or small teams) build it themselves. If you're at the front building and describing, they'll just tune out.
I would build some simple resistor ladders, which is probably all the course material covers. Have them put several LEDs in different parts of the circuit, and then play with the number and size of resistors in each leg of the ladder to show them, visually, that the voltage and current are changing.
You can show them capacitors by putting the battery in parallel with a big-ish cap, then have them remove the battery and watch the LED slowly dim and die.
If you want to bring transistors into the mix for sub-$5, it'd probably have to be a single transistor switching the power supply, with a pull-up wire to turn it on and off. You could maybe move it to different legs of the ladder. But I'd actually advise against transistors unless you want to go all-out and have them build an AND / OR gate. If you just show them transistor == switch, without showing them all the useful stuff it can do, they won't be very impressed.
If you have a digital multimeter, it would also be very instructive to build one demo circuit at the front of the class and measure the voltage at different points, to show them the values and prove something really is happening in there.
Anything more complicated than this, like RC oscillators or inductance, is going to be both expensive and way way over the heads of a 9th-grade class. At least, if you actually want to teach the physics of what's happening. If you just want to say "connect thingy A to jigamabob B and watch the light blink!" then sure, go for it!
Light bulbs and batteries (Score:3, Insightful)
Both items are familiar to the students, so they can be tricked into learning something new. Have them connect light bulbs in series, then in parallel, to see how the brightness changes. Add batteries in series. Add batteries in parallel. Once they are familiar, have them connect ammeters and voltmeters for numerical interpretation. This would give them a solid intuitive feel for how circuits work.
I would not teach them anything about transistors and capacitors until later, because that would require too many advanced concepts. Make sure the students do not feel overwhelmed by the material. If the students feel confident about what they are doing, ie. it makes sense that adding in more batteries makes it brighter, then they will be inquisitive to learn more, and confident enough to set out on their own.
Start with the oldies then move up. (Score:3, Insightful)
Tagged 'domyjobforme'? Really? (Score:5, Insightful)
Why is this tagged 'domyjobforme'? There's a negative connotation there.
This is an (awesome sounding) teacher looking for suggestions on how to expose kids to something worthwhile.
You aren't doing his job for him until you're working for his salary, on his budget, and care enough about your students to step outside the curriculum once in a while for education's sake.
What is this, the Hipster Olympics? Do we win by looking down our noses at people?
Re:Good Luck (Score:5, Insightful)
Soldering has no place in a public school.
Yeah. No one should be learning useful skills in public school!!!
Someone will burn themself, and sue.
As others have mentioned, do you also propose to ban welding in shop class? Alcohol burners in chemistry? Sheesh, you can get a rug burn if you fall down in basketweaving class. A little pain is good for you; pain is a sign of stupidity leaving your body. If nothing else, you learn to be careful with potentially dangerous tools. That is a (TM) Good Thing. Just accept the fact that you can't even get out of bed without accepting some risk and get over it. :rolleyes:
Someone will sue because of exposure to hazardous materials...
RoHS. Use lead-free solder. Problem solved. Besides, I've soldered with leaded solder since I was about tennnnnnn, and I'm just fine I'm just fine.
...or some government agency will get involved.
It's public school -- methinks that, by definition, a government agency is already involved.
Re:Light bulbs and batteries (Score:5, Insightful)
I disagree that capacitors and transistors are too advanced, or at least NEED to be taught in an advanced way. The goal is not necessarily to teach them how to design complex circuits, but to get them familiar with the ways the components interact.
Anecdote: I was building projects using transistors and SCRs as early as 6th grade. This included layout and chemical etching of my own circuit boards.
Let's see how many of the projects I can remember doing...
- Soil moisture sensor. Using a cut piece of double sided circuit board as a probe, connected to a small battery operated circuit that measured the resistance between the two sides. When the resistance rose above an adjustable threshold (via potentiometer) an LED would turn on to let you know the plat needed watering.
- "Concentration" game - an SCR and buzzer were used to make a game where you passed a metal loop over a bend metal wire without them touching. Once the two parts touched, completing a circuit, the SCR would latch on and the buzzer would sound until the reset button was pressed. I recall this project also used a voltage regulator.
- "Hide & Seek" game (aka the most annoying thing on the planet. Great for young students!). A set of transistors (4 as I recall) connected with a series of resistors and capacitors would periodically sound a short beep out of a small PC speaker. Duration, tone and period of the sound were adjustable by selecting the component values. As a bonus we were encouraged to find items at home to hide the circuit in - I used a hollowed out video cassette (switch under the flap) and hid in in my dad's video collection, complete with fake label :)
- 4-digit electronic keypad switch. A series of buttons were wired to transfer charge between a series of capacitors, and ultimately to an SCR that would latch a relay to control whatever you wanted to hook up to it. Combination was set by wiring the buttons differently.
- Roulette wheel. A series of LEDs (in a circular pattern) was connected to a small collection of ICs that would cycle them around and stop on one. I honestly don't recall what the ICs were, though :(
- Parallel port PC interface: Control up to eight 120V-10Amp relays via the PC's parallel port. (Included writing "driver" software)
- EQ meter. Build a resistor/diode network that, when fed an (amplified) audio source, caused a row of LEDs to light up according to the music volume.
- Various other blinkenlight projects :)
=Smidge=
Re:Do they still Sell 100-in-1 kits? (Score:1, Insightful)
Left to their own devices, without engineers and scientists (or artists, artisans, designers, and sometimes just plain laborers - the people who actually make and do things), everything businesspeople do is a useless masturbatory exercise. Well, ok, sometimes it does make some of the businessmen fantastically wealthy, but it usually only does that by taking money from people who have actually earned it and by destroying value and weakening the economy. Names like Ken Lay and Bernie Madoff spring to mind. I can't off the top of my head think of any way to actually create real value through investment, deal-making, lobbying, etc. unless there's actually a real product involved somewhere.
Businesspeople, as a class, tend to be greedy and also tend towards big egos. Therefore, they end up thinking that they're the ones who create the jobs, are entirely responsible for a businesses successes, etc. Engineers and scientists who think of it as a partnership, tend to find themselves buried in the organization, while the mbas end up with all the power.
Of course, the businesspeople are usually necessary as well to make businesses work and, if they become unnecessary, they tend to game the system to make themselves necessary. However, for most things that they do, there's no particularly good reason why the "scientists and engineers almost always work for other people [the businesspeople] as employees". The organization should usually work just as well if all the businesspeople are working for the engineers and scientists to keep the money flowing to the R&D department. It usually comes down to who cares more about being at the top of the organizational chart. Generally that's the businesspeople, while the engineers and scientists tend to care more about making discoveries, inventing things, etc. The scientists and engineers who focus on staying in control , eventually discover that they aren't really working as scientists and engineers anymore.
Multimeter (Score:3, Insightful)
Re:Good Luck (Score:3, Insightful)
Yep, but that's what our society has descended to, and doesn't seem to be turning around either.
This over-protective, risk-averse, entitlement-based mentality that our society has developed is going to make Western civilization completely irrelevant in 100 years I think.
Have to keep it simple, try RELAYS (Score:3, Insightful)
Hello-
I have some experience with this problem. You're right that microcontrollers are too advanced, everyone gets bogged down in the development tools. I also find that most types of IC and transistor circuits where you can't SEE what is happening don't really work out for most kids.
A few kids will get really into it. The next group will 'sort of' get things to work by following the directions, but not understanding what is actually happening. The rest will just sit there while everybody else plays around. They won't even try.
I have found that the basics like lightbulbs, batteries, and switches really get kids excited. They can see what's going on and they understand it and start building on it. Flipping a switch or pressing a button to make something happen is very empowering.
Next, if you can get a hold of some nice relays, especially ones with clear housings, they are really useful for this. It's a switch that turns on another switch. They understand it. (especially with a DPDT knife switch to explain things) Try a reed switch and a magnet, controlling a bulb through a relay. (small switch controls big switch... They learn about current) Let them try the NC contacts. Show them a relay LATCH. Connect the coil through the NC contacts for a relay buzzer. Add a speaker across the coil for a louder buzz. Can you combine these and make a burgler alarm? Show them that a mechanical bell or buzzer is the same as the NC relay buzzer. Next, put a capacitor on the relay coil for a delay. They will UNDERSTAND all this and get into it. And they like the clicking.
This lets them learn by using things they understand like switches and bulbs which are all doing things they can actually see. There are no black boxes at all. Also, a lot of kids want to ignore you and just play. With these parts, they can still make things happen and learn just by messing around. Can they get the relay to click? Make the bulb light up?
I've taught a lot of workshops to beginners and most breadboard type stuff really just confuses them. It seems they have made up their minds in advance that this is something they can't do, it's too hard. With the knife switches, batteries, bulbs and relays, they got really excited. When we added the capacitor they really understood what those did. It seems that this is a necessary first step before you move on to 'black box' parts.
Once you've gotten them there, the next thing is an optoisolator, which is really just a relay. Then they're comfortable with a DIP package, and you can proceed to the 555 and such with the ones you haven't lost. In the meantime, skip all semiconductors completely, except the rectifier diode, which they understand, and maybe the LED (with resistor already soldered on).
As we get better at electronics it becomes more and more difficult to understand what it was like to not know anything about electronics. You try to explain a 555 or op amp and there are a thousand details that you're taking for granted without knowing it. The other person really can't get it without the details, which makes it very hard to teach the subject without losing people. This is why you should go for the basics as much as you can. Let them play in that safe zone and master it and build a foundation before moving on.
Skip Ohm's law and the RC circuits and the math stuff for now. Let 'em turn things on and off. They'll get it.
List: Knife switch, lever switch with roller, button. Reed switch and magnet. Buzzer, bulb, rectifier diode. Clear relays, at least SPDT, DPDT better. Capacitor that can hold the relay on for 1 sec. LED with resistor installed. Speaker with resistor inline (so it can go across the battery without blowing up) . Batteries to match all these (9V or 12V is easiest)
Show them some examples and let 'em go nuts!
Re:NO!!!!! (Score:5, Insightful)
Don't use anything that will automate the work. Make the students do everything at a low-level if they are to learn anything. This is my opinion, only.
Start with basic theory - digital logic and Karnaugh Maps [wikipedia.org]. Introduce the clock and how it can manipulate the states of a digital logic device. Then pick something simple - like a stoplight controller, for example. And then create it.
Using the stop light controller as an example, you have a number of states that can be easily reduced with Karnaugh. Using a basic breadboard and logic gates (not more than a few bucks per head in bulk), the students should be able to design and build the stoplight controller. Use LEDs for a direct representation of the stoplights.
Extra Credit: put in a cross-walk button, corresponding states, Karnaugh maps, gates and LEDs.
Power Supply/Small BJT Amplifier (Score:3, Insightful)
Analog vs Digital circuits for teaching Physics (Score:3, Insightful)
Simple transistor audio amp for MP3 players (Score:3, Insightful)
I would suggest a project that is simple enough to understand, yet has a demonstrable practical circuit that they may choose to use after the class is over. One idea that quickly comes to mind is a simple (2-3-transistor or 2-3-per-channel (stereo)) audio amplifier, suitable to powering a small speaker, with a jack to connect to MP3 player.
It demonstrates one of two basic modes of operation for transistors, one of the most important semiconductor devices (diodes and ICs are others) that is a building block for analog (and digital) electronics. The other mode is when the transistor acts as a switch BTW.
You can cover electron and conventional current flow, waves (sound), and feedback as physics topics.
For the parts, using a mail-order suppler like Digi-Key [digikey.com], Mouser [mouser.com], or Jameco [jameco.com] (US / Canada) you should be able to buy the parts for about $5 including the connector and a small speaker.
See Simple 3 Transistor Audio Amp (50 milliwatt) [bowdenshob...cuits.info] from Bill Bowden's hobby circuits [bowdenshob...cuits.info] web site.