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kendallcp
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try a switching amplifier to drive the record head
kendallcp   8/1/2013 8:15:21 PM
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This is heartwarmingly retro stuff!

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.

betajet
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CEO
Be Prepared
betajet   8/1/2013 8:12:40 PM
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It's called "being prepared" :-)

My favorite bit from the Adam West / Burt Ward series:

Batman: Haven't you noticed how we always escape the vicious ensnarements of our enemies?

Robin: Yeah, because we're smarter than they are!

Batman: I like to think it's because... our hearts are pure.

 

betajet
User Rank
CEO
Plated why a memory?
betajet   8/1/2013 8:04:26 PM
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It was usually called plated wire memory and was used by the Univac 1100 series and other computers.

Max The Magnificent
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Re: Wire Recorders
Max The Magnificent   8/1/2013 5:09:28 PM
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@DrZuhock: Some of the first aircraft Black Boxes used wire recorders because of their durability.

Wow -- thank you for sharing this -- I learn something new every day!

Max The Magnificent
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Re: I so want one of these!!!
Max The Magnificent   8/1/2013 5:08:31 PM
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@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 max.maxfield@ubm.com 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.

Max The Magnificent
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Blogger
Re: Wire Memories
Max The Magnificent   8/1/2013 5:06:14 PM
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@Inquire8: I seem to recall that some computer mfgs were experimenting with wire memories back in the early 70s.

Someone else mentioned that -- it'sa logical development, but certainly someting of which I was unaware until now.

DrZuhoch
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Rookie
Re: Wire Recorders
DrZuhoch   8/1/2013 5:05:50 PM
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Some of the first aircraft Black Boxes used wire recorders because of their durability.

DrZuhoch
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Rookie
Re: I so want one of these!!!
DrZuhoch   8/1/2013 5:03:15 PM
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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.

Bellhop
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Rookie
Recording quality
Bellhop   8/1/2013 4:51:25 PM
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As "high fidelity", I'm somewhat underwhelmed, but it's certainly the best wire recorder ever built!

Inquire8
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Rookie
Wire Memories
Inquire8   8/1/2013 4:44:49 PM
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I seem to recall that some computer mfgs were experimenting with wire memories back in the early 70s.

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