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?
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
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 t
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.
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)..
There is a great little circuit for something called a "Drawdio" http://web.media.mit.edu/~silver/drawdio/ [mit.edu] 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.
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 [hackaday.com]. 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.
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).
They still have these but I can't imagine them having the longevity to stand up to ninth graders. After using mine for a few months most of teh spring had become elongated and knobs lost.
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.
Evolution doesn't control people's intelligence that much; the way they grow up does. And our society over the past 20-30 years has been in a serious decline.
I would do something with a 555 timer, there are a ton of applications and although you may consider it a 'microcontroller' all of the support electronics (pots, leds, resistors) will be instructive. Throw in an SCR to drive a high watt light bulb.
Seconded. I have a very simple circuit for an IR repeater which uses a 556 (that's two 555s in one IC), three resistors, one capacitor, an IR LED and a TSOP 1736 IR receiver. Total cost is less than $5 with a small breadboard, the latter being the most expensive component. One of the 555s is (ab-)used as an inverter. If you don't care too much about protocol, you can do away with that and just have a 50% duty cycle on the output instead of the usual 25%. The IR repeater works with almost all IR remotes (tho
Have them make a theremin [wikipedia.org] (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.
Have them make a theremin [wikipedia.org] (see the "Similar instruments" section as well). It makes spooky music. Great for a late-October/Halloween project.
Better yet have them build an E-Meter [wikipedia.org]. Since it is just a Wheatstone bridge they can learn something about physics. It doesn't produce spooky music but it would be great for scaring their parents at Hallowe'en.... "Mum, Dad look what I got for signing up with the scientologists!".
The problem with the Theremin is that to make a working example based on the principle of the original (capacitive coupling between the hands and antennas changing the frequency of an LC oscillator) is actually a fairly complex project - you have to understand about how LC oscillators work, the superheterodyne principle (the pitch oscillator is the difference frequency between a fixed and variable RF oscillator), transistor amplifier principles, etc. Of course, they can be built from kits, but just building from a kit doesn't really provide any insight into the functioning of the circuit.
A project that maintains the spirit of the original but might be easier for 9th graders to get a handle on might be the optical theremin [instructables.com]. It only uses a few parts, and the basic operation of the 555 timer and light dependent resistance should be approachable for newcomers to electronics.
I'd recommend a simple oscillator project. You can use it to either flash two LEDs or create tones for a speaker. It covers the use of transistors, resistors, and capacitors. The cost should be very low, and the project can be put together without solder in several different ways. Here is one article with an example.
Another trick is to make it in the audio range, and then have the kids draw a black square on a piece of paper with a pencil. The graphite (carbon) will appear as a variable resistance based on where you put the wires (put one wire at one end and move the other wire around). This will make a kind of crude music synthesizer. All for the cost of a 555, a speaker (piezo is fine), a battery, a battery holder, and a handful of resistors and capacitors.
Virtually anything digital will have one or more oscillators in it. The kiddies might well have fun with a 555 or discrete based oscillator. All the components(with LED or nasty little speaker to output the result, and a potentiometer or resistor selection for playing with frequency) are dirt cheap in even modest quantities and the theory of operation is a step above bulb 'n battery without being super tricky.
Crystal radio - tons of fun, relevant to kids (music), super cheap. There are kits online, but a little more expensive than your budget ($12 - $15). I'll bet you could get the cost down by buying the raw parts in bulk instead of individual kits.
I'd start with a crystal radio [wikipedia.org], 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 [uoguelph.ca] and some LEDs.
All of these are low power, low cost, and produce a visible or audible result for immediate gratification.
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/.
$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.
I think the scrounging idea is a good one...you'll be able to pull resistors off of anything, and everybody will learn the codes quickly. Have them bring in something simple in their house that doesn't work - have them troubleshoot and repair it (permission, obviously...).
Have them bring in an annoying electronic toy and have them wire a volume control into it. For that matter, have them bend circuits on all the electronic crap that surrounds us today.
Finally, talk to your later Radio Shack / Fry's / whatever, and see if you can get them to sponsor the class with some free gear and projects.
If you end up with some more coin, try a TV-B-Gone:
AdaFruit has a lot of good stuff. One thing I saw at a Make Faire was a project where you quickly build an oscillator using a paper circuit board and a pencil line drawn on a paper to have a quickie musical instrument.
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 [larwe.com] 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 [geocities.com]
If you want to liaise further, feel free to contact me using that website.
Get the chemistry teacher to help you and make a trench(foxhole) radio.
Then build a crystal radio.
Then an audio amplifier circuit.
Or build the crysal radio then the audio amplifier then the foxhole radio. But actually building a radio with parts they've made and not bought, making the diode, will teach them a lot.
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?
its very simple. it gets you results FAST. very little learning curve.
I went from zero (or near zero) to a full running real-world program in a few days (talking to lcd displays, reading from an IR led and handheld AVR remote control, relays, leds, buzzers, etc).
the source code is all out there and its simple. you can find a lot of thru-hole chips that you can 'talk to'. chips are in the $5 range and need only a 50cent ceramic resonator (not even a crystal) and you're up and running.
at this point, anyone exiting school who CANNOT program microcontrollers (not computers, but the smaller controllers) will be left out in the cold. I think the next big thing is small controllers, not 'big' pc systems. get into this early, it will pay back and the ideas/knowledge gained map well to 'pro' level controllers.
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. [digikey.com] 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. [cogeco.ca])
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.)
I hit "submit" just as I realized that 556s are a better bet: two 555s on one chip, and Digikey has them for 55 cents per unit, or 50 pieces for $22. [digikey.com]
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)
How about a power supply they can use to charge their small devices? All you need for a basic power supply are a transformer, some diodes, resistors and capacitors.
Or a small voltage divider bias BJT amplifier? a couple capacitors, an NPN transistor, and some resistors. Could be used to amplify music coming from an iPod and show the principals of amplification.
At $5 each, there are few options. Rainbow Kits [rainbowkits.com] are a possibility.
The "blinking lights" and "1W audio amplifier" kits are both under $5.99. That's about as low as you can go.
I don't think soldering irons are a requirement for this idea. Breadboards, or even springboards, would be much more appropriate, I think. Cost per student goes up, but overhead goes down.
You didnt have a shop class in high school? I took metal shop and got to play with welding torches. That had a much higher potential for getting seriously hurt than a soldering iron.
I still want to give a swift cockpunch to my school for that same policy. I'm looking at paying to take a welding class at the local community college so I can work on my car.
Instead I had to sit around and take a Study Hall because god forbid smart people learn to do two things.
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.
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.
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.
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" [amazon.com] 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" [amasci.com] Also read all his articles about "Electricity" [amasci.com] 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 [satcure-focus.com] 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 [corbina.net].
Other good projects would be an H-bridge motor controller [beam-wiki.org] (6 transistors) or for something more ambitious a Tilden "nervous net" / BEAM robotic circuit such as a light-tracking head [beam-wiki.org].
1) Is fun
2) Teaches about circuits that are relevant to their life.
3) Doesn't rely too heavily on a black box microcontroller.
4) Individual components would probably be better.
5) I want them to understand the circuitry behind modern tech.
Given these criteria, I would vote, go for a flip-flop. Even the name appeals to kids. Its also historically the basis of a lot of digital electronics design. Its also fun as kids can see the LEDs working and replacing the resistors with potentiometers makes it easily to alter its speed interactively which is always fun for kids to see.
But I would say, as you are teaching electronics, before you move onto the flip-flop then first show them a single Transistor with a small switch wired to its base, showing the Transistor can itself act like a switch (use it to control an LED). They need to learn how transistors switch. (You can go onto explain about amplifying later... start with digital on-off operation, then expand to in between voltages, using a potentiometer on its base).
Both the flip-flop and the switch with a transistor + LED (and a few resistors), all adds up to less than $5 for the lot and you have a few important lessons easily covered in an interesting and visual way.
You can also make the flip-flop switch faster so they can't see the LEDs flashing any more, and then connect up a small cheap speaker, so they can hear it buzzing to show its still flipping. Its a very interactive way for kids to learn electronics, and its cheap and easy to make without even needing a circuit board. Just use tinned wires to form the circuit exactly like its circuit diagram.:)
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.
A-stable multivibrator (Score:5, Interesting)
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 t
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=
Parent
Re:Light bulbs and batteries (Score:5, Informative)
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 [electronics-lab.com]
something fun and useful...a 'hearing aid' =) ... the entire site is useful
http://www.aaroncake.net/circuits/ [aaroncake.net]
some things more complex...
http://sci-toys.com/index.html [sci-toys.com]
fun and educational .. some real easy stuff...and some more challenging stuff...
Hope this post ranks high enough for you to find it.
Parent
Light bulbs are old, make a Joule thief... (Score:5, Informative)
Make all those 'dead' batteries run little torches:
http://www.emanator.demon.co.uk/bigclive/joule.htm [demon.co.uk]
Parent
Re:A-stable multivibrator (Score:4, Funny)
Astable multivibrator
don't you have to be over 21 to buy those?
Parent
Re:A-stable multivibrator (Score:5, Informative)
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.
Parent
Re:A-stable multivibrator (Score:5, Interesting)
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 [hackaday.com]. 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.
Parent
Do they still Sell 100-in-1 kits? (Score:5, Informative)
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: (Score:3, Informative)
They still have these but I can't imagine them having the longevity to stand up to ninth graders. After using mine for a few months most of teh spring had become elongated and knobs lost.
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.
Parent
Re: (Score:3, Interesting)
Evolution doesn't control people's intelligence that much; the way they grow up does. And our society over the past 20-30 years has been in a serious decline.
555 Timer (Score:3, Interesting)
I would do something with a 555 timer, there are a ton of applications and although you may consider it a 'microcontroller' all of the support electronics (pots, leds, resistors) will be instructive. Throw in an SCR to drive a high watt light bulb.
Re: (Score:3, Interesting)
Seconded. I have a very simple circuit for an IR repeater which uses a 556 (that's two 555s in one IC), three resistors, one capacitor, an IR LED and a TSOP 1736 IR receiver. Total cost is less than $5 with a small breadboard, the latter being the most expensive component. One of the 555s is (ab-)used as an inverter. If you don't care too much about protocol, you can do away with that and just have a 50% duty cycle on the output instead of the usual 25%. The IR repeater works with almost all IR remotes (tho
Re: (Score:3, Informative)
Getting shocked as a teenager builds character. I should know!
A Theremin (Score:4, Interesting)
Have them make a theremin [wikipedia.org] (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.
Re: (Score:3, Funny)
Now that's a good suggestion. The only risk is that all the students will become fans of really weird movies [avclub.com]!
E-Meter (Score:3, Funny)
Have them make a theremin [wikipedia.org] (see the "Similar instruments" section as well). It makes spooky music. Great for a late-October/Halloween project.
Better yet have them build an E-Meter [wikipedia.org]. Since it is just a Wheatstone bridge they can learn something about physics. It doesn't produce spooky music but it would be great for scaring their parents at Hallowe'en.... "Mum, Dad look what I got for signing up with the scientologists!".
Re:A Theremin (Score:4, Informative)
The problem with the Theremin is that to make a working example based on the principle of the original (capacitive coupling between the hands and antennas changing the frequency of an LC oscillator) is actually a fairly complex project - you have to understand about how LC oscillators work, the superheterodyne principle (the pitch oscillator is the difference frequency between a fixed and variable RF oscillator), transistor amplifier principles, etc. Of course, they can be built from kits, but just building from a kit doesn't really provide any insight into the functioning of the circuit.
A project that maintains the spirit of the original but might be easier for 9th graders to get a handle on might be the optical theremin [instructables.com]. It only uses a few parts, and the basic operation of the 555 timer and light dependent resistance should be approachable for newcomers to electronics.
Parent
Nice book (Score:4, Informative)
SIMPLE, LOW-COST ELECTRONICS PROJECTS
http://www.elsevier.com/wps/find/bookdescription.cws_home/677563/description#description [elsevier.com]
A simple oscillator (Score:4, Informative)
I'd recommend a simple oscillator project. You can use it to either flash two LEDs or create tones for a speaker. It covers the use of transistors, resistors, and capacitors. The cost should be very low, and the project can be put together without solder in several different ways. Here is one article with an example.
http://www.arrl.org/news/features/2003/10/30/1/ [arrl.org]
Re: (Score:3, Interesting)
Another trick is to make it in the audio range, and then have the kids draw a black square on a piece of paper with a pencil. The graphite (carbon) will appear as a variable resistance based on where you put the wires (put one wire at one end and move the other wire around). This will make a kind of crude music synthesizer. All for the cost of a 555, a speaker (piezo is fine), a battery, a battery holder, and a handful of resistors and capacitors.
Oscillator? (Score:3, Insightful)
Crystal Radio (Score:3, Interesting)
Crystal radio (Score:5, Interesting)
I'd start with a crystal radio [wikipedia.org], 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 [uoguelph.ca] 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 (Score:5, Informative)
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.
Desoldering old stuff? (Score:3, Interesting)
What about getting junked electronics (thinking Goodwill here, or possibly even donated) and desoldering components to build other projects with?
electric guitar stompboxes? (Score:3, Interesting)
a small guitar amp or an overdrive stompbox are pretty easy to build from discrete components and you can hear if they work or not.
Scrounge, Circuit Bend, talk to local Radio Shack (Score:3, Informative)
Have them bring in an annoying electronic toy and have them wire a volume control into it. For that matter, have them bend circuits on all the electronic crap that surrounds us today.
Finally, talk to your later Radio Shack / Fry's / whatever, and see if you can get them to sponsor the class with some free gear and projects.
If you end up with some more coin, try a TV-B-Gone:
http://www.adafruit.com/index.php?main_page=index&cPath=20&sessid=5bf624d376f9c6c44a119200f35c990d [adafruit.com]
AdaFruit has a lot of good stuff. One thing I saw at a Make Faire was a project where you quickly build an oscillator using a paper circuit board and a pencil line drawn on a paper to have a quickie musical instrument.
Lewin Edwards (Score:5, Informative)
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?
anything arduino (Score:4, Interesting)
its very simple. it gets you results FAST. very little learning curve.
I went from zero (or near zero) to a full running real-world program in a few days (talking to lcd displays, reading from an IR led and handheld AVR remote control, relays, leds, buzzers, etc).
the source code is all out there and its simple. you can find a lot of thru-hole chips that you can 'talk to'. chips are in the $5 range and need only a 50cent ceramic resonator (not even a crystal) and you're up and running.
at this point, anyone exiting school who CANNOT program microcontrollers (not computers, but the smaller controllers) will be left out in the cold. I think the next big thing is small controllers, not 'big' pc systems. get into this early, it will pay back and the ideas/knowledge gained map well to 'pro' level controllers.
555 ICs are God. (Score:5, Informative)
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:555 ICs are God. (Score:4, Informative)
Parent
Multimeter (Score:3, Insightful)
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!
Power Supply/Small BJT Amplifier (Score:3, Insightful)
Options at $5 each (Score:3, Informative)
At $5 each, there are few options. Rainbow Kits [rainbowkits.com] are a possibility. The "blinking lights" and "1W audio amplifier" kits are both under $5.99. That's about as low as you can go.
Re:Good Luck (Score:4, Informative)
I don't think soldering irons are a requirement for this idea. Breadboards, or even springboards, would be much more appropriate, I think. Cost per student goes up, but overhead goes down.
Parent
Re:Good Luck (Score:4, Informative)
Parent
Re: (Score:3, Interesting)
I still want to give a swift cockpunch to my school for that same policy. I'm looking at paying to take a welding class at the local community college so I can work on my car.
Instead I had to sit around and take a Study Hall because god forbid smart people learn to do two things.
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.
Parent
Re: (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.
Re:Good Luck (Score:5, Interesting)
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.
Parent
Re:use spice (Score:5, Informative)
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.
Parent
Mimms, yes and Bill Beatty and BEAM (Score:5, Interesting)
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" [amazon.com] 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" [amasci.com] Also read all his articles about "Electricity" [amasci.com] 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 [satcure-focus.com] 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 [corbina.net].
Other good projects would be an H-bridge motor controller [beam-wiki.org] (6 transistors) or for something more ambitious a Tilden "nervous net" / BEAM robotic circuit such as a light-tracking head [beam-wiki.org].
Parent
Using the criteria ... (Score:4, Interesting)
2) Teaches about circuits that are relevant to their life.
3) Doesn't rely too heavily on a black box microcontroller.
4) Individual components would probably be better.
5) I want them to understand the circuitry behind modern tech.
Given these criteria, I would vote, go for a flip-flop. Even the name appeals to kids. Its also historically the basis of a lot of digital electronics design. Its also fun as kids can see the LEDs working and replacing the resistors with potentiometers makes it easily to alter its speed interactively which is always fun for kids to see.
For example...
http://talkingelectronics.com/FreeProjects/5-Projects/Page16.html [talkingelectronics.com]
But I would say, as you are teaching electronics, before you move onto the flip-flop then first show them a single Transistor with a small switch wired to its base, showing the Transistor can itself act like a switch (use it to control an LED). They need to learn how transistors switch. (You can go onto explain about amplifying later
Both the flip-flop and the switch with a transistor + LED (and a few resistors), all adds up to less than $5 for the lot and you have a few important lessons easily covered in an interesting and visual way.
You can also make the flip-flop switch faster so they can't see the LEDs flashing any more, and then connect up a small cheap speaker, so they can hear it buzzing to show its still flipping. Its a very interactive way for kids to learn electronics, and its cheap and easy to make without even needing a circuit board. Just use tinned wires to form the circuit exactly like its circuit diagram.
Parent
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.
Parent