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

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: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.

Light bulbs and batteries

[PleaseFearMe]

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.

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=

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?

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: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.

Analog vs Digital circuits for teaching Physics

[hashwolf]

If you want to teach PHYSICS, I recommend against digital circuits. There is much more Physics to learn from Analog(ue) circuit design and implementation. Indeed the first circuit I ever built was an AM radio reciever, according to instructions found on my school Physics textbook: "Physics for Today and Tomorrow" by Tom Duncan (IMHO the best Physics book ever) The component count is very low, about 10 components... the most expensive and difficult to find? of which are the the ferrite core and the variable capacitor. An AM radio receiver can be used to teach about electromagnetism, resonance, electronics, etc. Students wishing to go that extra mile can attempt to also build an AM transmitter (this can be even easier to build.)