A site of homemade physics and electronics experiments, such as memristors, cathode ray tubes, TEA lasers, and flame triodes.
Commenters call it full of great experiments, are glad it is still online, and point to it for non-transistor devices and simple radios.
There's another similar such element - which has a somewhat confusingly similar name:
https://en.wikipedia.org/wiki/Memistor
It was developed by Bernard Widrow in 1960, whereas the memristor was envisioned and named in 1971 - but not found to actually exist until 2008.
The memistor was most "famously" used to develop a couple of artificial intelligence (neural network) systems, ADALINE and MADALINE:
https://en.wikipedia.org/wiki/ADALINE
Note that if you try to google "memistor", you'll maddeningly get suggestions and results for "memristors" instead - even when you tell google to show you only results for memistors only; this makes finding information about them online difficult. It's best to add to your search "adaline", "madaline", and/or "widrow".
The main difference between the two devices are that the memistor is a three-terminal device, versus the memristor being a two-terminal device. You can think of the memistor as being a "memory transistor" vs the memristor as a "memory resistor". This is gross simplification, of course.
One other interesting thing about ADALINE is how simple the memistors are to construct; you can effectively re-create ADALINE at home, as Widrow's paper shows:
http://www-isl.stanford.edu/~widrow/papers/t1960anadaptive.pdf
On the topic of memristors - they can be DIY'd as well:
http://sparkbangbuzz.com/memristor/memristor.htm
Finally - if you're interested in this kind of thing (that is, implementing hardware analogs of brain…
No, it wasn't Spotify, it was Muzak. Muzak went bankrupt in 2009, but for decades, they provided piped-in music for stores and elevators, distributed over phone lines.
The Teleharmonium was one of those painful things people built before power amplifiers. It had a big AC generator for each audio note. That's why the thing was so huge. They had no way to amplify, so they had to generate each note with a big enough generator to drive all the speakers in the system. At any given time, only a few notes were active, but all the generators were turning. This wasn't a promising line of development.
Tone generation using rotating machinery did make a comeback in Hammond organs of the late 1930s, which had a tone wheel for each note. This system had amplifiers, so the tone wheels were small. Hammond organs were noted for being absolutely in tune; all the wheels were on the same shaft, and driven by a synchronous motor, so they had to stay in sync. The Hammond was a good organ, and emulations of the original models are still sold.
There's a whole history of early amplifiers. Edison even built a steam-powered public address system, the "Steam Shout". This was a diaphragm connected to a needle valve in a steam line. It was apparently a flop. However, now that we understand how to build fluidic amplifiers, it might be worth revisiting that idea. It would be a good accessory for a steam calliope.
Other early attempts at an amp include Edison's "chalk telephone", the…
I've looked into that as well. There are a bunch of lasers that are DIY-able, and AFAIK dye-based lasers are the only ones that really require "chemicals".
TEA lasers are basically just a few pieces of metal and high-voltage, seen them at high-school level quite a few times: http://www.sparkbangbuzz.com/tealaser/tealaser7.htm
CO2 lasers are relatively complex and are easiest if you buy some parts readymade, but can be completely homebuild as well: http://jarrodkinsey.org/co2laser/co2laser.html
There are tons of ressources online, a good overviw over different possibilities and basic information can be found here: http://www.repairfaq.org/sam/laserfaq.htm#faqtoc
Thanks! I'd long wondered exactly how radio carriers were modulated before vacuum tubes. (Technical details of that era are often skimpy in histories.)
This chronology of AM radio is interesting: [https://web.archive.org/web/20071118155548/http://members.aol.com/jeff560/chrono1.html] It mentions Fessenden's 1906 Xmas broadcast, and it looks like he'd just gotten one of Alexanderson's alternators.
Paul Mali, Magnetic Amplifiers (1960;PDF)
[https://web.archive.org/web/20061114175548/http://www.pmillett.com/Books/mag_amp.pdf]
Home-made MA's: [http://sparkbangbuzz.com/mag-amp/mag-amp.htm]
Aren't there groups out there doing one-off chips using ion implantation?
One could envisage a machine that takes a silicon blank and blasts it with a steerable beam of dopant ions, similar to a small scale Cathode Ray Tube, with the silicon in place of the phosphor. A CRT is feasible to DIY [1,2]. What about an ion implantation device? Okay, it won't do 14nm features first up, but could it make a working transistor??
[1] http://www.instructables.com/id/DIY-Electron-Accelerator-A-Cathode-Ray-Tube-in-a-/
[2] http://www.sparkbangbuzz.com/crt/crt6.htm
Yes, memristors are real, and no, their properties are not magic[1]. As I stated elsewhere on this thread, you can even make them at home[2]. It's even been discussed here on Hacker News before[3].
[1] https://electronics.stackexchange.com/questions/76097/what-are-the-characteristics-of-a-memristor
[2] http://sparkbangbuzz.com/memristor/memristor.htm
[3] https://news.ycombinator.com/item?id=9853984