I was going to save this for a rainy day but I'm too excited to get it posted because it's pretty awesome.
I came by this through a friend who was helping clean out a storage space. It's a Webster Chicago wire recorder, model 18-1P, which seems to date from somewhere in the 1940s.
This is intended for use in an office setting, taking voice memos so that a secretary can later play them back and transcribe them. Wire recording is a precursor to tape recording, and this device looks and works pretty much like a reel-to-reel tape deck. Instead of recording on audio tape, however, this device records on to a steel wire. The mechanism is otherwise exactly the same: the storage is magnetic, and the wire runs past a read/write head (with the very retro Webster Chicago logo on it):
Here's a spool of the wire:
Pretty great. However, this particular player wasn't working when it came to me -- it has two fuses built into the power plug (photos later), and both were blown, probably because the power cord is mangled and rotten after all these years:
And the power plug, with the Bakelite casing removed. (I wonder why they opted for a cute name for Bakelite instead of just using its chemical name, "polyoxybenzylmethylenglycolanhydride"?)
That's two bus fuses, with the plug terminals mounted directly to one of each end and the wire attached via a brass coupling to the other. I got new fuses from Magnet Home Hardware on Commercial, who I have yet to stump with any reasonable request for a stocked item. My favourite guy there has broken one arm and sprained another -- that's all the arms he has. I hope he's well on the mend.
And I can restrain myself no longer. Look -- this hardware is beautiful! Yes, it's just a power jack, but it's made to last, built of honest materials in pieces that won't disappear between the fingers and get lost between the floorboards. It's not so cheaply made that every edge is razor-sharp. It's intended to be serviced by a human being. It even has instructions on the back:
Here's the plug again with the wire replaced -- and this is in no way the usual "ogle my craftsmanship" maker post, because all I'm doing here is replacing a power cable (with a piece of wire I got from Free Geek, $1.60 spent). I'm posting this because I want you to appreciate what electronics craftsmanship used to be.
It's very unusual to see fuses right inside the power plug -- usually they'd be somewhere inside the chassis -- but it's actually a pretty smart place to put them. In this case the power cable itself was shorting out, and since the fuses are right at the wall, they will take the hit in this kind of failure. A plain old power plug and cable of the more usual type would've caused a breaker to blow rather than the built-in fuses, as the fuse would've been placed after the point of failure.
OK, allow me to compose myself and wipe my nose and I'll return to the machine. I soldered the new wires in (and soldering wires to 70-year-old terminals really feels like communing with ancestors). This got it closer to working -- the mechanical parts worked, i.e. the motor spun and the tape spooled -- but there was still something wrong with the audio circuitry.
So I shelled it properly and had a look inside:
That's quite a bit to take in all at once. At the bottom left is where I soldered the new power cable. Most of the center is taken up with bits and pieces of the mechanics -- a leaf switch that's controlled by the play/rewind control, and underneath that, the motor and associated parts. At the top, some dead-bug circuitry, the speaker, and a couple of transformers (probably one for audio, one for power).
And, at the bottom left, some vacuum tubes for the audio amplifier. These, the ancestors of modern silicon-based semiconductors, were present in the pioneering days of home stereos, television, radio transmission, and even computers -- ENIAC, the first general-purpose electronic computer, contained 17,468 of them.
When it was invented, the silicon transistor made vacuum tubes obsolete and revolutionized electronics manufacturing, starting a race towards miniaturization that continues now -- with hundreds of millions, even trillions, of them just in the CPU of a modern home computer. Moore's Law has predicted the doubling of computer complexity every two years, based on the number of transistors. This trend has held for over 50 years.
Vacuum tubes have a lot in common with light bulbs. They're glass envelopes enclosing a vacuum and a filament that glows when power is passed through it, but unlike light bulbs, they also contain various metal grids and electrodes, depending on what they do. (They're amazing, intricate little devices -- watch, for example, one fellow making them by hand.)
I noticed that one of the vacuum tubes was not lighting up, so I pulled it from its socket and took it up to Main Electronics for a replacement. Vacuum tubes are not in common use -- except perhaps in specialized high-end audio equipment and guitar amplifiers -- so they're now very specialized equipment, manufactured by very few companies. Mesa Boogie, for example, still makes tubes for guitar amplifiers, but you could probably count their fellow manufacturers on one hand.
Main Electronics is 40 years old this year and has really seen it all -- the old HAM radio hobbyist days, the dawn of cheap transistorized home electronics, the decline (and some would say demise) of North American electronics manufacturing in the late 1970s and 1980s, the beginning of the home computer revolution, up to the new generation of Arduino-powered hobbyists.
But they haven't forgotten their roots (ahem, Radio Shack) -- or their warehouse stock. They have a vintage vacuum tube tester on one of the store counters and a good supply of replacements, many of which even survived a warehouse fire some years ago. When I asked the fellow at the counter for a 6AU6, he handed me back a genuine RCA Radiotron Electron Tube -- "The Fountainhead of Modern Tube Development is RCA; World's Best Known ELECTRON TUBES" -- never used, totally brand new, but probably warehoused for over 30 years.
It's not the Ark of the Covenant, but hey, this is real life, not Hollywood. Thank you just for existing, Main Electronics.
With the new tube popped in -- hold your breath -- it works.
It's hard to distinguish what anyone is saying -- probably part old wire, probably part old circuitry -- but I can make out a little of the conversation. I'll explore the two spools I have for anything juicy.
Anyone who knows me well will have already spotted the excellent face on the front of the thing.
So there we have it -- 70-year-old technology brought back to life with a couple of fuses, a new power cable from the Free Geek scrap bin, and a vacuum tube that's probably been shelved for 30 years. All this to play a signal on a wire that might itself be approaching 70 years old. I hope I can find some comprehensible parts of the conversation...