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The Humble, Yet Mighty, Resistor

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mhrackin
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Re: Carbon microphones
mhrackin   10/20/2014 4:20:57 PM
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@David: I didn't catch this until today! Funny thing: when I was about 10 or 11, I came across a handset from a defunct 500 set. At that time (like most folks) we had exactly one telephone. Since I spent 95% of my time in our basement (lab and workshop), I decided I needed an "answer only" phone. I constructed one with my very limited knowledge of telephony; as I had no idea what the "induction coil" did or why it was needed, I just put the earphone and carbon mic element in series, and thence to a standard phone plug. I mounted a jack on a metal bracket, and wired it "bridged" across the phone wiring (conveniently accessible in the basement just above my lab bench). When the phone rang, I just plugged in the handset; it worked amazingly well (in retrospect) although I always wondered why the "sidetone" was so much louder than a "real" telephone. These "coincidences" just keep coming! We HAVE to get together sometime to further compare notes!

GSKrasle
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Re: Voltage rating
GSKrasle   10/20/2014 4:04:54 PM
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There is a white-paper that I have found useful for trying to get better instrumentation accuracy from shunt resistors: h t t p : / / w w w .analog.com/library/analogdialogue/archives/46-06/shunt_resistors.html

David Ashton
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Re: Who knew the humble resistor covered so much?
David Ashton   10/10/2014 7:16:02 PM
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@mhrackin... " Amazingly (for the EET site) not one post having to do with food or eating!"

Well I'd wondered about that, but thought it was cheating to introduce the subject myself...

@Wnderer:

picky-palate.com/2014/04/07/parmesan-rosemary-brussels-sprouts-bacon-pizza/
This recipe can be adapted to use bagels instead of pizza dough to make cheesy-bacon-brussel-sprout-pizza-bagels!

Well since you have mentioned Bacon and Bagels we should get Max AND Martin Rowe chiming in any moment now :-)

David Ashton
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Re: Carbon microphones
David Ashton   10/10/2014 7:11:51 PM
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@MHRackin...interesting....I worked on Nortel PABXs (telephone switches) until fairly recently.  All the phone set types have number designations (2216, 2616, 3904, etc) and an analog phone is configured as a "500".  Always wondered why, now I know.  I built myself a "butt" phone when I was training (ca. 40 years ago) with an old phone handset, a mushroom tin and a rotary dial.  It had a carbon earliece.  I reconstructed the PCB to one which would fit on the back of the dial inside the mushroom tin, and used an oscillator switched to the earpiece as the "Ringer".  It was still at my place in Zimbabwe till recently, it must have been "appropriated..." - pity, as it had very sentimental attachments.  

GSKrasle
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Re: The Symbol font is depricated - use Unicode
GSKrasle   10/10/2014 3:15:45 PM
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Wndrer, ANSI.SYS did exactly what you want, but also opened the door to some juvenile pranks. It allowed you to define keys, CTRL+Keys, etc to functions different from usual. Wikipedia has a good article on it.

GSKrasle
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Re: The Symbol font is depricated - use Unicode
GSKrasle   10/10/2014 11:57:55 AM
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David, That's what the 'Alt+digit-digit-digit' method does. You can find tables for FOUR-digit access codes, but some symbols are also available in three digits. There doesn't seem to be a published list of those. You can also use 'Insert/Symbol' and under that you can see the defined keyboard shortcuts and define new ones. I don't use those shortcuts b/c I move from computer-to-computer too much.

mhrackin
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CEO
Re: Who knew the humble resistor covered so much?
mhrackin   10/10/2014 10:52:14 AM
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Touche! [seems like the EET IT gods have eliminated the ability to format the text which also allowed insertion of symbols like the "e" with a '). Or maybe that's a feature now blocked from my IE9.....  Yup!  I can see the insert link below now... I'm editing in FireFox. è (special shortcut for Canadians.....)

Wnderer
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Re: Who knew the humble resistor covered so much?
Wnderer   10/10/2014 10:16:50 AM
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@mhrackin Or are you re-posting on this topic to ensure the "food link" string stays alive?

I thought you were pointing out a food link was required for legitimate number one most commented status.

mhrackin
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CEO
Carbon microphones
mhrackin   10/10/2014 10:11:00 AM
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David, you stated "Early telephones used carbon microphones" (a bit paraphrased from your original). I know for certain (as had been associated with the manufacturer) that these were STILL in production into at least the late 1990s. Our factory (in Corinth, MS) had a special room that was the workshop of the guy whose job it was to take the special grade of coal (from a mine in Pennsylvania owned by the company) and crush, grind, and sort by grain size the carbon for these mike elements. I suspect he retired (or died???) around 2000 or so, and once the inventory of "his" carbon ewas gone, they dropped the carbon elements and telephone designs using them from their catalog. I still have a few 2500 sets (the touch-tone equivalent of the rotary-dial 500 sets that were the "modern" design introduced in late 1950s). One of them in my basement shop is still in use (although I do have to whack the handset against the top of the workbench once in a while to unpack the carbon granules).

mhrackin
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CEO
Re: Who knew the humble resistor covered so much?
mhrackin   10/10/2014 9:59:39 AM
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Was that link on this blog? With a record (excluding caption contest ones) 18 pages, it's hard to keep track! Or are you re-posting on this topic to ensure the "food link" string stays alive?

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