I never throw anything away,and I still have one in my shop somewhere...I'll see if I can find it and send pictures.I don't remember the last thing recorded on it, it was used as an office stenographer.
@DrZuhoch: I still have one in my shop somewhere...I'll see if I can find it and send pictures.
Please do send the pictures to me at firstname.lastname@example.org and maybe we can do a follow-up column on this. I'd also love to see some pictures of a wire recorder being used as a form of computer memory as mentioned elsewhere in ths icomment thread.
Many years ago a company I worked for used the technique that these devices use to measure the length of steel wires. It worked very well and was sold into the cable/wire making industry for some years. If you want to see a comercial version of the the science museum in London UK did have one on display. very impresive with reals about 4ft in diameter. Roger
@Set Square: If you want to see a comercial version of the the science museum in London UK did have one on display...
I last visited the London Science Museum in 2010 when I was speaking at the Embedded System Conference (I also got my picture taken standing next to the "Dr Who" style Police Box outside of Earl's Court Tube Station, but that's another story) ... but I don't recall seeing this in the museum ... maybe it' sjust a case of not knowing what I was looking at...
@Set Square: If you are into Doctor Who, then if you ever find yourself in Bradford, yorkshire...
I've been into it ever since i saw the very first episode back in 1q963 when I was 6 years old!!! I'm from Sheffield, Yorkshire -- I occasionally get back to see my mom and little bro' -- the next time I'm over I will definately try to get over to Bradford to the National Media Museum (after which you can expect to see a follow-up blog) -- thanks for the suggestion!!!
In the summer of 1953 I received a one month appointment as an Engineering Aid (GS-4, $3175.00 per annum) at one of the three Signal Corps Engineering Labs at Fort Monmouth, NJ following Signal Corps ROTC Summer Camp at Camp Gordon GA. My assignment was to run tests on a prototype wire recorder for field use built by General Electric. The wire was very springy like piano wire and had a tendancy to pop off the spools. If you had the missfortune to drop a spool, it took an hour or more to untangle and rewind the wire, not something that could be done in the field. The other problem I recall had to do with the variation in read signal as the wire twisted and the read head saw the side of the wire the record head had seen and then the other side.
A tape recorder was being evaluate at the same time and was vastly superior. In fact the wire recorder had already been rejected. In retrospect that may be reason I was given this task. Nevertheless it was a good experiance.
No mention of where these things came from? The first I've seen wasn't a recorder, it was a radio detector: a loop of moving wire with two coils touching, antenna on the first coil and headphones on the second, and a magnet to restore the wire afterwards. "Marconi Magnetic Detector." Nonlinear effects presumably demodulated the RF. I guess it was a Coherer with a single giant iron filing.
Hmm. Was this the origin, or did wire recorders predate 1910 or so? Firesign Theater of course insists that they were invented by native americans who recorded civil-war era theater dramas...
The first magnetic wire recorder was created in 1899 by a Danish Engineer called Valdemar Poulsen (1869 – 1942). Commercial magnetic wire recorders for dictation and telephone recording were made almost continuously from the 1920s onwards, but the real heyday of wire recording was in the 1940s through to the mid-1950s.
Not only do I have a actual working wire recorder but it came with what I think is a historic recording of Father Devine leading his congregatin in a refrain of "If It Had Not Been For Jesus, I Would Not Be Here Today." '
I've been wondering for years what to do with this machine. Perhaps I should contact Mr. Woods?
@Tom: I've been wondering for years what to do with this machine. Perhaps I should contact Mr. Woods?
Mr Woods is building his own ... I on the other hand am sitting here with a little reat rolling down my cheek because I do not own a magnetic wire recorde (sad face).
Have you seen the video in my Welcome to the Pleasure Dome blog about my office? I would be DELIGHTED to make room for a wire recorder ... quite apart from anything else I already have a boxed spool of recording wire here in the office with a note on the back that seems to indicate it contains a recording -- I've long wondered what is on that wire...
I had heard of wire recorders several decades ago when I've watched some of the old WWII movies. When they wanted to record something (surreptitiously) they always used a "wire recorder" complete with a bobbin of "wire". One advantage of wire over tape would be the environmental "extremes" that the wire could survive versus a tape.
My favorite episode of Patrick MacGoohan's Secret Agent (aka Danger Man, in the UK) was the one in which the secret message was recorded on the twisted wire used to hang a picture in the spy's apartment. Can't do that with magnetic tape! Fortunately, MacGoohan was carrying a tiny wire playback machine so he could hear it. (I never leave home without mine).
@Tom: Fortunately, MacGoohan was carrying a tiny wire playback machine so he could hear it.
That reminds me of the old "Batman & Robin" film where batman is hanging from a rope ladder under the Bat Copter when a shark jumps out of the sea and attaches itself to Batman's leg ... and Batman shouts up to Robin "Pass me the Shark-Repellent Spray" -- and you see Robin in the cockpit reach for a rack containing four cans of sprak ... and sure enough one is marked "Shark Repellent" ... what are the odds?
@betajet: Batman: I like to think it's because... our hearts are pure.
LOL It was so sappy -- I loved it as a kid. I remember whenever the Riddler created a riddle and they solved it and the solutuion was so wild and wacky ("... and what eats an unripe banana at three o'clock in the afternoon Robin...") but it all seemed to make perfect sense when you were a kid... you just thought they were really clever to sort out the clues :-)
I messed around with primitive PWM amplifiers a little in the 80s, and always wanted to - but never got around to - replace the conventional HF bias + audio drive scheme in my home-made cassette deck with a straight square wave drive width-modulated with the audio.
In those days you had to roll your own, but these days there are some - already long in the tooth - PWM power amplifier configurations that can run at around 50kHz. Stick the audio signal into that and drive the resulting current into the head - should produce a myuch broader dip in the distortion curve and be less critical of bias level versus metal formulation. Simpler circuitry too - no separate bias power amp and record driver.
When (not if, Max!) this gets published in EET, I'd like to get hold of a table of the frequency response data, pre-equalization. I'm the first person to get excited about doing special filters, but this is a case where a digitally-implemented equalizer could probably do a super job. Implemented on the replay side, you could use a reel of calibration wire to give standardized excitation, and then everyone's wire recorder can be calibrated to have a super-flat frequency response! If that's what floats your boat, anyway.
In response to kendallcp: it works! I did it with tape back in the early '70s, and unknown to me at the time, Joe Dundovic of Nortronics (tape heads) was experimenting with it too. Tape goes "gracefully" into distortion when overdriven, and the only thing you have to watch out for with PWM is reaching the point when your duty cycle disappears and audio peaks slam the supply rails into the head. This can be obviated with some form of limiter ahead of the PWM circuit, or by comparing your audio waveform with a 'peaky' clock, rather than a triangle, to generate the PWM.
Another neat trick that works, sort-of, is to get rid of the AC bias altogether. It's possible to predistort the audio waveform in a manner opposite to the hysteresis-loop function of the recording process, although this requires fancy phase compensation as well as the nonlinear transfer. This gets rid of the "biased-tape noise," and really improves the high-frequency performance. The tradeoff is 'modulation noise,' which can be eliminated by applying a sort of 'dithering,' which puts the biased-tape noise right back. Such fun!
Lots of security agencies used wire recorders during spy activities. There was a brand in Austria creating extremely small types of wire recorders, called 'Miniphone'. Have a look at our website http://www.cryptomuseum.com/covert/minifon/mi51/index.htm to see one of those Miniphone recorders and also note the wrist-watch where a microphone is hidden inside. There was once a spy captured on an airport. Because he wore 2 watches, since this watch was not able to run on time (no watch mechanics inside this silly thing ;-)
Other examples are wire recorders to record in flight information. The Russians had a beautiful designed tiny wire recorder in their MIG airplanes. One advantage is that wire can withold high temperatures. the 'pack of wires' isolate those inside the 'pack', hence, big chance of signals recovery once a plane has been crashed...
Anyway, lots of excamples to be found and big fun to play with.
@alzie: I started out with tape recording half a century ago...
Doesn't it feel strange saying stuff like that? It's like when I'm talking about my friend Brian Bailey and I say: "I attended a class Brian gave on SCAN technology around 30 years ago and I still have the notes."
But I refuse to get any older -- I'm going to hold at my current age for the next 100 years or so -- good grief, I'm only just starting my third chaildhood!
Being the only EE in my extended family, I inherited my grandparent's broken console-model wire recorder. In a burst of energy in my 30's, I pulled the electronics out, replaced a broken tube or two, then got it working. Because the motor bearings and transmission were worn out, it ran under-speed, and all the voices were low and slow. Powering it from a variac transformer, dialed up above 110Vac, I was able to 'tune' the speed, so that Grampa's voice sounded right. But it took about 5 muffin fans aimed at the electronics and motor, to keep it from thermal meltdown.
I discovered recordings of my Grampa's barbershop group singing on the radio, and also found a recording of my dad teaching my youngest uncle to talk.
Dubbed over to cassette tape, those copies made great Christmas gifts for the extended family that year.