Low-Budget Electronics Projects For High School?

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?

Comments

A-stable multivibrator

[yoshac]

Astable multivibrator is a simple circuit, useful (flash lights at high RC values, make sounds at higher values), and teaches the basics of transistor, capacitor and resistor in a practical manner

Re:A-stable multivibrator

[tylerni7]

There is a great little circuit for something called a "Drawdio" http://web.media.mit.edu/~silver/drawdio/ that kids really love, basically it's an astable 555 that makes a noises with pitch proportional to how long they draw pencil marks. (it's a bit hard to explain quickly, just try the video on that website)
I teach middle school aged kids electronics at a local workshop, building things such as that, and I can tell you it's very doable to make projects for cheap that kids can build and understand.
The main issues that I have found is the board on which you lay out projects. Breadboards are expensive, and not permanent. PCBs don't allow kids to experiment with their own circuit designs, and unless you are going to take the time and money to let them design their own boards that might not work and then etch them, it's more trouble than it is worth. We use a more traditional breadboard concept that is just an actual, wooden board. Then we have kids use copper tacks and strips to lay down the circuitry, and then they solder things directly to that.
As other people have mentioned, soldering irons are a bit annoying, and a couple kids might get some mild burns, but as long as you don't mind the initial cost, it's totally doable.
One of the great things about the drawdio project, is it allows you to hook it up to a oscilloscope and show the kids more about sound, or hook the piezo speaker up to a computer and run some FFT software, so they can see and hear how the resistance changes the pitch.

Other things to look into are basic transistor circuits, things with opamps, counters, or things with binary to decimal or binary to seven segment LCD chips.

Re:A-stable multivibrator

[blincoln]

The 555 can be used in a lot of interesting, simple projects. I like the idea of audio, because it's something that (IMO) a lot of young students will find interesting compared to some of the other typical beginning electronics projects.

One very easy 555 project is an Atari Punk Console. I built one of those a couple of years ago and took it to a party and it provided hours of entertainment.

Another option might be a simple resonant low-pass filter, since any of the students who've listened to electronic music will immediately recognize the effect and want to play with it.

Do they still Sell 100-in-1 kits?

[JSBiff]

When I was middle-school age, I had a *great time* with these kits sold by Radio Shack. They were basically a bunch of cheap electronic components fixed on some sort of board, with connections, and a bunch of wires you could use to connect the components together into different circuits. It even came with a book with like 40 or 100 (I don't remember the number, really) different circuits 'plans' for simple types of things you could do with the kit and discussions about how the circuits worked.

They cost like $10 or $20 back then (probably be $30 or $40 now, not sure though).

I would *highly* recommend looking into something like this. They are maybe a bit more expensive than you discussed, but they are re-usable and allow you to create lots of different things. Heck, you could maybe even figure out how to use multiples of the kits and maybe a few additional components to create something a bit more impressive to demonstrate to the class how larger electronics systems are created by configuring each kit into a specific type of circuit, then joining the kits together (that is, each kit becomes one 'components' of a larger system, maybe).

Re:Do they still Sell 100-in-1 kits?

[JSBiff]

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.

A Theremin

[davidwr]

Have them make a theremin (see the "Similar instruments" section as well). It makes spooky music. Great for a late-October/Halloween project.

You can even make this inter-disciplinary with the music teacher, the English teacher, the history teacher, and the Russian teacher as appropriate.

Crystal radio

[Mal-2]

I'd start with a crystal radio, although there are designs far more compact than the one on Wikipedia. Next, perhaps a simple transistor amplifier (for which you can use the crystal radio as an audio source), then it might be time to move on to the thousand and one projects you can build around a 555 timer chip and some LEDs.

All of these are low power, low cost, and produce a visible or audible result for immediate gratification.

Mal-2

Optical Theremin

[micromegas]

I just taught a unit on electronics. We used breadboards and the 555 ic to build optical theremins. I have the entire curriculum done. contact me through /.

Cost effective?

[girlintraining]

$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:use spice

[ocularDeathRay]

another option, and I just mentioned him on another story the other day... is take a look at the old forest M Mims III books. They are the books that they used to sell for a couple bucks at radioshack. You can still get them from his website, or a few other places (saw them at Fry's the other day) although they cost a few dollars more now. I started reading his books in the 4th grade and I have worked and played with electronics ever since. Each of his books have schematics (and a guide on how to read them) for many projects which can be built for a few dollars on a breadboard. I would suggest looking at something with a simple linear analog IC like a 555 or 556 timer.

If you go to jameco.com you can get component grab bags, or my favorite are the component kits. For example the resistor kit has a selection of common values and a nice plastic storage thing that keeps them nice and neat. Give every student a few LEDs from a grab bag, a 555 timer chip, a battery, some jumper wire, a handful of capacitors and resistors from a couple of component kits, and the schematics to make a simple LED flasher. Then the different students will have different values of resistors and capacitors, and will get different results. Then you can time the flashing of each students project and chart the values of resistor, capacitor, and time. Explaining simple RC circuitry is a good place to start teaching somebody electronics.

The Mims books also get into digital, you could buy some simple nand gate chips and show the students all the different ways to use them, use simple push buttons for input and LEDs for output to save money. It may not be super exciting, but you could build an inventory over a couple years to do something really cool. Use TTL chips, not CMOS because the students will ruin CMOS with ESD. The possibilities are really endless. Any students who really get excited can buy a handful of parts online and build all sorts of neat stuff from those books. There are circuits for opto communications devices, a shortwave radio, a break beam sensor, you name it, its in there.

Lewin Edwards

[larwe]

I am working on some similar projects for 11-12th graders though my budget is more in the $10 per student range. There are challenges with doing this without (a) soldering - and the risks, and (b) lead exposure. Anything intended for kids younger than 13 needs to be Pb-free to meet CPSC guidelines and avoid liability issues. For 9th graders you might need to check ASTM regs also regarding choking, entanglement, etc. It's a bit of a bear and it becomes harder the younger the kids get. I am using largely recycled components from junk cellphones and other sources (TDMA cellphones in particular are available dirt cheap and have lots of interesting projects) - http://www.larwe.com/technical/2260lcd.html documents some of my reverse-engineering though it doesn't explain why I'm doing it). A couple of interesting projects that can be made without soldering (just twisting wires) - Use a Hall effect sensor or reed switch, in combination with a light (LED, bulb, whatever) and a handful of small magnets to demonstrate making a "recording". Glue the magnets onto a strip of paper, or just use a piece of tape sticky-side up. Pull the tape past the sensor and watch the bits as they're read out on the bulb. Works best if you color say all the north poles red, so they can work out what is 0 and what is 1. - Make a light-following robot with two pager motors. There are a load of designs around, this one is not the simplest but is illustrative http://www.geocities.com/SouthBeach/6897/photovore.html If you want to liaise further, feel free to contact me using that website.

Tagged 'domyjobforme'? Really?

[neiras]

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?

555 ICs are God.

[w3woody]

There are so many things you can do with an 555 IC that it's not even funny. Digikey has them for 44 cents per unit here. With a handful of descrete components you can create everything from flip flops (with 2 555 ICs) to oscillators to time delay circuits. (some example circuits.)
I suspect with a handful of 555 ICs, descrete circuits, ICs and switches (or just touch wires together), you can easily create a whole host of illustrative experiments that show the idea behind modern gate circuits. And I'm sure you can easily do it all for a few dollars worth of components, though unfortunately breadboards can be quite expensive. (Around $8 for a small breadboard through Digikey, though you may be able to find cheaper.)

Re:Good Luck

[element-o.p.]

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

[Smidge204]

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=

Light bulbs are old, make a Joule thief...

[Joce640k]

Make all those 'dead' batteries run little torches:

 

http://www.emanator.demon.co.uk/bigclive/joule.htm

Re:NO!!!!!

[dsginter]

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. 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.

Re:Good Luck

[Savior_on_a_Stick]

I did something similar, except we were grab assing and I was vaulting my workbench.

My hand landed on the hot iron with my weight fully, though briefly on the hot iron.

Did you immediately jam the burned flesh into your mouth to cool it?

People still look at me oddly when I tell them that fried human flesh tastes a lot more like sauteed mushrooms than pork.

Mimms, yes and Bill Beatty and BEAM

[Savantissimo]

I agree - the Mimms books are the place to look for basic, cheap yet informative and interesting projects. I used his "Getting started in Electronics" to teach ages 9-12. To make this learning physics rather than just a craft project, it's crucial to teach the basics before doing projects with complicated circuits or chips. I mean at least voltage, current, serial resistance and parallel conductance using the water-flow analogies, and preferably the divided-pressure tank model of the capacitor as well (see Bill Beatty's "Capacitor Complaints" Also read all his articles about "Electricity" or you will be guaranteed to perpetuate misconceptions. Great teaching ideas there.) This is about as much as you are likely to have time for, but very little interesting happens in circuits without semiconductors, so if you can work in the fluid analogies for diodes (check valves) and transistors the kids will benefit.

My personal choice for an educational medium-basic circuit project would be a high-pass and a low-pass single-pole filter (both just a capacitor and a resistor). Use a computer sound card as a signal generator and spectrum analyzer using a free program such as OscilloMeter.

Other good projects would be an H-bridge motor controller (6 transistors) or for something more ambitious a Tilden "nervous net" / BEAM robotic circuit such as a light-tracking head.

Re:Light bulbs and batteries

[huckda]

Deciding I needed a PWM for a project, I wanted to build my own to learn about electronics...so I went to radio shack and bought their $79.99 Electronics Learning Lab.(this kit alone is HOURS of amusement and learning)...but what I learned quickly is that following the Mimms book was very wasteful...the explanations of what is happening is scant...the diagrams are great, but blinking leds and making buzzer noises just ISN'T practical to a freshman in High School(I've taught them Freshman computing and mentored them in many aspects of I.T.)...

Below are some sites I've come across searching for 'simple enough for a basic solderer' and with readily available components(strip parts out of busted old computer power supplies/vcrs/radios/etc)..

http://www.electronics-lab.com/projects/audio/023/index.html

something fun and useful...a 'hearing aid' =) ... the entire site is useful

http://www.aaroncake.net/circuits/

some things more complex...

http://sci-toys.com/index.html

fun and educational .. some real easy stuff...and some more challenging stuff...

Hope this post ranks high enough for you to find it.