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> Digital Keyer, Schematic Needed
cgriggs
Posted: June 27, 2017 02:30 am
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I built a digital keyer back in the 70's or 80's and didn't leave a reference for it in the case. I've been thinking I got the idea from 73 Magazine or a Radio Amateur Handbook. (I may be wrong.)
It incorporates three 555's, which, if memory serves me, was fairly common back then. It's self contained with power supply and audio and I'd like to vary the tone, if possible.
Would anyone know the whereabouts of such a schematic?
Charlie
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Jimthecopierwrench
Posted: June 27, 2017 02:54 am
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Hmm, your timeline doesn't sound too far off - though the 555 wouldn't have been jellybean cheap in '73. quickly went through my covers 70- 74 and didn't see anything though. will have a cigar and check a bit slower.

Presumably one 555 would have been a tone generator, and the other two one shots for timing the dits ad dahs. I'd figure the oscillator would be operating so long as the bug is powered, so probing (each) pin 3 on the 555's for the one with the continuous tone would tell you which is which.

Once identified, altering the R/C components - or swapping a timing resistor for a linear pot .. will get you where you want to be for tone adjustment.


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Jimthecopierwrench
Posted: June 27, 2017 03:03 am
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Argh .. The cover August 1976 looks promising and I know I have that issue .. but where?

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Jimthecopierwrench
Posted: June 27, 2017 03:13 am
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This it?

http://www.americanradiohistory.com/Archiv...ics-1976-08.pdf

Begins on page 44.

(Stumbling across decades of PE pdf's = Oh yeah baby!)


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MacFromOK
Posted: June 27, 2017 03:20 am
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QUOTE (Jimthecopierwrench @ June 26, 2017 08:54 pm)
Presumably one 555 would have been a tone generator, and the other two one shots for timing the dits ad dahs.

Well... color me dumber than a stump, but isn't the operator responsible for the duration of the dits and dahs? I really don't see the need for more than one 555 for the tone generator.

What am I missing here? huh.gif


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Jimthecopierwrench
Posted: June 27, 2017 04:00 am
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Far as i (thought I) knew electronic keyers took care of the character lengths (i'd imagine even spaces in high end rods) .. Uh, I only glanced at the schematic but I think I caught a pair of FF's doing duty in this case. Undoubtedly these devices were regarded with disdain as 'cheating' by old timers of the era.

I've never really studied some of the Rolls Royce mechanical keys with all of the adjustments, springs, and weights .. weren't these also designed (albeit to a lesser degree) to 'delay' the contact breaks to form character length?


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MacFromOK
Posted: June 27, 2017 04:57 am
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I thought they were mainly to aid in softer/faster (and perhaps less tiring) operation. But wasn't duration of dits and dahs still up to the operator?

I don't even do Morse (though I've looked into it a good bit), so I may be more clueless than I think. dunno.gif


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cgriggs
Posted: June 28, 2017 02:14 am
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I looked through a folder of old schematics, that I had in a filing cabinet and found my keyer article. I believe it was in an "Amateur Radio Handbook" from the 70's or early 80's.
I had made copies of pages 172 through 178 from Chapter 7 of (?). I could find no other information relative to the publication.
If someone has an old RAH, maybe you could see if Chapter 7 covers transistors and IC's.
I also discovered a side tone oscillator schematic I had added to the keyer circuit so I'll play with that to possibly vary the tone. We shall see.
I think I'll check ebay for old ARH's.
Charlie
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Jimthecopierwrench
Posted: June 28, 2017 02:22 am
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Chapter 7 in my 1975 ARRL edition is UHF/VHF transmitting.


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cgriggs
Posted: June 28, 2017 02:37 am
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Perhaps it wasn't RAH? Whatever it came out of had more than 200 pages, I'm guessing. I can't think of what I might have had that would have been that thick.
I'll probably never know.
Charlie
On edit: Mac,
The 555's controlled the dits, the dahs and the spaces. (According to the article.)
Jim,
Forgive my ignorance, but what is a pair of FF's?
(I'm going to hate myself for asking, I know, but I've forgotten SO much!! LOL )
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Jimthecopierwrench
Posted: June 28, 2017 04:02 am
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QUOTE
Forgive my ignorance, but what is a pair of FF's?


No such thing as ignorance in asking anything here .. I didn't chalk up 10K posts here because I knew stuff .. I got 'em because I didn't (well, along with general banter and stuff with me mates).

FF short for Flip Flops. Neat little bits of fundamental bistable letching logic that (I will do disservice to in this poor description) - are the basic blocks in one form or another of digital memory, counters, etc.

I suspect that application specific integration - I doubt there are many circuits with multiple ICs that would still be built ground up with gates and such - has killed them off at the hobby level as far as use to perform a specific task.

For example, a decade counter circuit presented to a mag reader in the late 60's might have used several "JK" type FF's, but a few years later would likely have just used a dedicated counter IC. (7490, 74192, etc.)




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Jimthecopierwrench
Posted: June 28, 2017 04:08 am
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QUOTE
...controlled the dits, the dahs and the spaces.
...
QUOTE
...operator responsible for the duration of the dits and dahs?


Well, thinking about it arse backwards .. wouldn't need multiple IC's just to key a transmitter - so if the bug wasn't introducing some sort of timing, then why all the hardware?


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MacFromOK
Posted: June 28, 2017 05:16 am
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QUOTE (Jimthecopierwrench @ June 27, 2017 10:08 pm)
so if the bug wasn't introducing some sort of timing, then why all the hardware?

That was kinda my point... biggrin.gif


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cgriggs
Posted: June 28, 2017 09:31 am
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Oh boy! Talk about tickling the memory buds! LOL It's coming back. I have to admit to being kind of scared off back then by the high tech aspects of electronics and sticking with "old fashioned" tubes ect. If the circuit called for 3 transistors or 6 tubes, I'd be gathering up the tubes. ... sigh ... Looks like I'm going to have to pick up where I left off! Lots to learn and relearn, I'm thinking. lol
Charlie
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Jimthecopierwrench
Posted: June 29, 2017 10:55 am
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My frustration (with the evolution of the craft) the last long while has lain between love vs. use - or need if you will.

Ie. There's nothing I could build in a week that I couldn't buy for $5. laugh.gif .

The early 90's were "my time". Perhaps because I had more time and patience - though less money. I'd build things for the sake of understanding the components. The ECG catalog and databooks that I'd dug from dumpsters my bibles.

It seemed like you could do 'anything' with the surplus digital gear of the era with a few gates or transistors jiggered into the works - my particular love was connecting the universe to my old Commodore computers.

No forum back then, so I thought that I was about the best guy I knew doing this stuff.

Now you can buy modules that do a hundred times anything I did. Great if you want a certain function .. but where's the fun? yet what's the point in tearing your hair out building half of what you could buy?

I think there was something of a reward in having cool stuff that you'd built in the day as well, and the gee-whiz looks of visitors.

Think touch tone pocket dialer or such .. or an actual example: I once built a scratch answering machine (though even then you could buy one for $40 or so) that would log the time stamp on one of my PETs - 50 pounds of hardware that caught every eye that walked by.

And imagine how unimpressive that would be today laugh.gif .

Or those who spun their own HERO clones (rudimentary 80's robots pushed to market to catch the "we'll all have android love dolls and flying cars in 15 years" craze). 10 year olds are putting those to shame with LEGO now.

Tubes are still here to be certain, having made an impressive come back actually - but (sadly) they can't compete with modern function any more than their grandchild the basic logic gate now.

That is to say .. what do you need that you might be able to build with any number of tubes?

I myself keep mulling the hell out of that question .. because if I could use a bit of glass to get 'er done I would as well.

Picked up a bunch of uh .. 6E5? I forget - tuning eyes a while back, just in case I find something that needs one.

Actually, one was originally allocated as a dashboard "economy gauge" indicating (albeit uselessly) more or less relative pedal position in case my foot couldn't figure it out. Never installed it because my idgit dog would have broken it off.

Lol - old ferriers wrenching on steam engines. Ah well.



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cgriggs
Posted: June 29, 2017 12:20 pm
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"The early 90's were "my time". Perhaps because I had more time and patience - though less money. I'd build things for the sake of understanding the components."

You put a lump in my throat with that! The 60's and 70's were my hay-days. The only thing I couldn't let go of when I dropped out of electronics was the DC-40 that started out as a kit and was so modified that today I can't begin to work on it. LOL It started out as a single board and ended up as 7 interconnected home-brewed pc boards. What a tangled "mess". But it still works great as a receiver!!! (Didn't finish the transmitter part.)

I meant to add a vfo (board 8) and eliminate the crystal, but "the ultimatum" came into play and that ended that. Oh, gar, how I miss those days!!

We are a dying breed. It seems that, in today's market, it's easier to buy Chinese than to build something. More "book learning" than "hands-on experience," I guess you could say.

What I'm mainly interested in accomplishing, now that I'm 83 and waiting on God, is that I can wring a qso out of the tri-bander I just built. I expect it back from Pacific Antenna any day now and will tackle it asap. I'm finding that when soldering, you need a magnifying glass, a good soldering pencil and much, much patience. ... sigh ... LOL

If you look like Alfred E. Newman too, then I would say that we're kindred spirits from different generations. LOL

Charlie
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