Basic Amp Build for teaching electronics

[J M Fahey]

Just as a reference, here is one sample of what building a tube amp during a class means , if done professionally.
Amp building classes by Bruce Egnater himself.
Bruce Egnater - Amp Building Classes And Kits, Tube Amp Classes And Kits, String instruments

FWIW he might even fly to UK if somebody assembled the necessary amount of pupils to justify the trip.

Way too much for what I think is the intended target, but pictures and videos are worth watching anyway, you might get a couple good ideas out of them (or discard a couple bad ones )

[Chuck H]

Small compared to teaching an entire class any physics related to even simple amplifier function, but I mentored a senior project for a friend of my daughter on a strat build. All parts were pre made. That is, no wood shop involved. Parts were purchased. The actual "skills" of the project to be demonstrated were basically scratch project comprehension, research skills, then finishing, assembly and a little electronics comprehension at the end. But we only made it about three quarters through the project and never even got to the wiring before he had to present it. He still managed an A for the project. That says one of two things. Either the system is too lax and doesn't expect much of high school students (because I had already done this in junior high school) or the actual planning and execution of even this level of research and assembly is highly skilled and regarded and I simply didn't recognize common limitations when I did it for myself years earlier.?. I guess what I'm saying is, if you want to see who stands out this is a great project. I wouldn't expect more than a few students to demonstratively "get" the lesson more than partially. And they should get credit for certain. There are a lot of aspects to it. I was modifying, wiring and otherwise building my own electric guitars with some understandings at fourteen. But amplifiers are next level. I would have been of only partial understanding in such a class at that time. So take the results for what their worth WRT individual performance. Most of all, recognize those that shine and guide them in the right direction because they are probably genius or very close.

[MarkusBass]

I don't think that kids will be enthusiastic when they buy LM386-based amp. I would suggest a simple tube amp - between 1 and 15W, with ready to use components. With tube amp, you will be able to teach kids how transformer and other parts of an amp work.
I'm sure there are such projects available in UK. In Poland I can buy this project:
https://amptone.pl/kit2202-5W - you can clearly see that this is an amp based on Marshall. You get everything except the enclosure (which you can buy separately). The cost is about 200 Pounds. I don't think that this is much. It's clear that when you build the amp, you get an amp that can be used by professional musicians. This could make the kids proud of their work.

Mark

[mikepukmel]

I don't think that kids will be enthusiastic when they buy LM386-based amp. I would suggest a simple tube amp - between 1 and 15W, with ready to use components. With tube amp, you will be able to teach kids how transformer and other parts of an amp work.
I'm sure there are such projects available in UK. In Poland I can buy this project:
https://amptone.pl/kit2202-5W - you can clearly see that this is an amp based on Marshall. You get everything except the enclosure (which you can buy separately). The cost is about 200 Pounds. I don't think that this is much. It's clear that when you build the amp, you get an amp that can be used by professional musicians. This could make the kids proud of their work.

Mark

Those are really nice looking kits!

[mikepukmel]

Sadly, Im in the camp of steering your school project away from vacuum tube circuits, due to 250v-300v B+ for even small 5 watt EL84 based amp circuits. The chance that one student, during the course of building and debugging their amps, would stick their finger in a live amp is scary.

Maybe you could start them off breadboarding a solid state amp.

Then if they get that working, they could design a circuit board using Eagle or one of the other schematic/circuit board programs, take the parts off the breadboard and solder them into their circuit board, and mount that in a project box. They can get a good version of Eagle for free, its main limitation is only the size of the board, which is plenty for this kind of project. They could purchase self contained power supplies, further reducing the risk of sticking fingers into high voltage.

You could teach them a lot of electronics with relatively low safety risk.

[rjb]

Some questions

- What is the title of the class? General Physics? Introduction to Electronics? The Science of Sound...?
- How long does the class run? How long is your semester/marking period/whatever?
- Would the project be undertaken in class? As homework? As an after-hours extra-curricular activity?
- What is your time allotment? A semester? A month? A week? An afternoon? A class period?
In other words, what is the desired scope of your project?

[rjb]

Then if they get that working, they could design a circuit board using Eagle or one of the other schematic/circuit board programs, take the parts off the breadboard and solder them into their circuit board...

Where's the part where they manufacture the circuit board?

Not saying that's unreasonable- but a bit of effort for maybe one unit in a general physics class, for kids who might also have other classes and activities....

Then again, they might be like this kid.

[eschertron]

In other words, what is the desired scope of your project?

Right, We've been offering suggestions and admonitions while all the while totally in the dark about what kind of class is envisioned. Someone can build an amp in a weekend, come away with absolutely no gained knowledge. They can start from ground up, starting with rudimentary electronics theory, learn to read schematics, and by the end of a term be able to rationally discuss the historical and engineering aspects of tube amplification. Maybe even get a little acoustic/psychoacoustic theory in the mix. What's the take-away for the students? What are they expected to understand by the end of the class?

[beezerboy]

how about a tube preamp with a SS power amp... all on lower voltage than wall power. have at least one speaker cab set up so each student can at least check the project after completion. if it works ok, thats motivation to build a cab

[loudthud]

I put safety as top priority. This means solid state with either a wall wart (AC transformer or DC output) or laptop style power supply (DC output). Many laptop style switchers can tolerate Mains Voltages from 100V to 250V. The most important feature of the power supply is the safety ground. Many of the available power supplies have leakage currents from the Mains that could cause mild shocks to guitar players, hum or damage to some circuits.

So first task is to find a suitable power supply.

[rjb]

The more I think about it, the more I like the Bazz Fuss (post #10).

-rb