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Morse code led without a micro controller

kellys_eye

Jun 25, 2010
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Yes, as a former Radio Officer (merchant marine) the true SOS sound is ingrained in memory and discernible through any interference and at practically any (low) signal level. If the signal wasn't as you state it was quickly ignored (many Greek ships used to run their group callsign into one syllable and try to 'fake' the SOS sound just to get attention).

The 30 time slots also rings bells for the design I did - it actually used two 4515 counters and associated parts so the component count is well above any other the great examples shown above AND illustrates where microcontrollers really can excel as this would be the ideal situation for a simple 8-pin (6 pin?) version and two external parts!
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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It would be tempting to implement this with a fifteen-stage Johnson ring counter, which would be eight dual-D flip-flops (with one flip-flop left over). Maybe use the redundant flip-flop to reset the counter at the end of each SOS sequence, "just in case" a "forbidden state" sneaks into the sequence... nah. PIC it is.:p
 

Wiginometry

Nov 29, 2017
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Many years ago, near the end of the TTL (Transistor-Transistor Logic) era, and at the beginning of the CMOS logic era, I became interested in generating NTSC composite sync for use in a video game I was attempting to design. So, having some time on my hands and a large stock of TTL parts, I designed and bread-boarded a complete NTSC fully interlaced composite sync generator. I was soooo happy when I finally got it to work and had the interlace timing correct. Then, a few weeks later IIRC, I ran across an integrated circuit that did exactly the same thing for a really cheap price. I was crushed! All that work (weeks of it) just to re-invent someone else's wheel! I was determined to never let that happen to me again. And so led the path down the road to microprocessors... And I never did get around to finishing that video game because others beat me to it.

did you happen to make a schematic for it? That sounds fun regardless of wether it's "outdated" heck I still play Atari, nes, and other "dated" systems. (Really wish I could find a Commodore....)
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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If the goal here is to use components you already have in a box why limit yourself to solid state? :)

Chris
upload_2017-12-26_10-40-33.jpeg
 

AnalogKid

Jun 10, 2015
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Many years ago, near the end of the TTL (Transistor-Transistor Logic) era, and at the beginning of the CMOS logic era, I became interested in generating NTSC composite sync for use in a video game I was attempting to design. So, having some time on my hands and a large stock of TTL parts, I designed and bread-boarded a complete NTSC fully interlaced composite sync generator. I was soooo happy when I finally got it to work and had the interlace timing correct. Then, a few weeks later IIRC, I ran across an integrated circuit that did exactly the same thing for a really cheap price.

Working nights at a TV station in the early 70's, I did the paper design for an all-TTL sync generator, then checked it against the National Semi MM5320/21 (probably the part you're referring to). I started a design using a binary counter driving an EEPROM, but about half way through it the station bought a DVI(?) digital timebase corrector and it had basically the same thing fully developed.

ak
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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I started a design using a binary counter driving an EEPROM, but about half way through it the station bought a DVI(?) digital timebase corrector and it had basically the same thing fully developed.
Almost exactly my experience with TTL! Almost all of the necessary engineering had already been done by the time I got involved with TTL in the late 1960s into the 1970s. No way I could compete in price or time-to-build with commercial off-the-shelf (COTS) equipment. It had to be a one-of-kind project. And some really spiffy LSI TTL was becoming available that further simplified the engineering required to complete a project. The icing on the cake was the arrival of the Intel line of microprocessors. I was late getting involved with that too... another "super technician" in our lab had discovered the 4004, and other processors from Motorola and others, and was busy experimenting with them. He even bought a KIM-1 computer with his own out-of-pocket money!

But being a little higher on the food chain, I held out for a modular Intel 8080 minicomputer-style system using rack-mounted card modules: one card for the CPU, one card for the clock generator and bus controller, one card for each kilobyte of RAM, another card for serial I/O... yada, yada, yada. IIRC, the company I bought all this stuff from was named Control Logic, but I cannot find a trace of them today. Control Logic is a common enough name though, so they may have gone out of business or were absorbed by another company.

Our electronics lab supported the University of Dayton Research Institute as well as every department and school on campus. Across the hall from our lab was a surface analysis lab, my first introduction to that particular science. It initially had an hemispherical electron spectrometer used with a monochromatic x-ray generator to analyze the surface chemical structure of samples in vacuum. It seemed to take forever (hours) to scan through the range of photoelectrically emitted electron energies to identify and quantify each chemical species, in the meantime recording on a linear chart recorder the response from an electron multiplier that detected electrons of a specific energy that made their way through the hemispherical analyzer. The chart recorder ran at a constant strip-chart speed that was not in any way coherent with the slowly changing waveform that determined the analyzer energy window. It was therefore difficult to accurately interpret the results.

So, realizing the power of expensive minicomputers, and the potential power of inexpensive microprocessors, I proposed to "upgrade" their ESCA (Electron Spectroscopy for Chemical Analysis) system to allow automagical sweeping of analyzer energy selection and storage of digital count data from the electron multiplier detector. There were multi-channel analyzers available that could do the same thing, essentially a memory matrix into which the number in a binary counter could be transferred to sequential memory locations and then "read out" as vertical deflections on a CRT screen, but these were expensive. And interfacing the digitally stored information to a mainframe computer was a daunting task.

The lure of being able to build something on the cheap that would free up hundreds of man-hours spent baby-sitting the ESCA was irresistible. I got the go-ahead to proceed, using the Control Logic card chassis as the basis for my very first embedded microprocessor application.

Only thing was... I didn't know Jack about how to program a microprocessor. Or how much RAM was "enough" or even how to download and store a program in RAM. Long story short: we had to eventually purchase an Intel Microprocessor Development System (MDS) to finish the project, and hire a grad student to program the Control Logic box. Not that I didn't learn a lot. I signed up for, and passed, a course in IBM 360 Assembly Language Programming, figuring it would help me understand how to program the Intel 8080. Well, not so much, but it was enough to convince me I did not want to pursue a degree in computer science. But I did purchase, and for awhile used, a paper-tape based Editor, Assembler, and Loader for the Control Logic system.

We used an ancient ASR-33 Teletype machine to punch and read paper tape, interfaced to the Control Logic chassis through a 20 mA serial current loop. So the drill was this: Read in the editor from paper tape. I had built a tape boot-loader that read its small program from a Hollerith card inserted in a static card reader. The card was multi-punched manually, in binary, from hand-assembled 8080 instructions, each 12-bit column on the 80 column card representing one byte of data... in effect an 80 byte paper ROM. More than enough memory for a paper-tape boot-loader.

Next, use the Editor, now loaded into RAM, to write an assembly language program. Punch the ASCII representation of this source program onto paper tape. Read in the Assembler program, replacing the Editor program, and create a relocatable binary object file from the source file paper tape. Punch out the relocatable binary object file on paper tape. Finally, read in the Loader program, specify a starting address, and create a loadable hex object file from the relocatable binary object file. Punch out this absolute binary object file on paper tape. Finally, using the Hollerith card bootstrap reader program, load the binary object file into RAM and see if your program works.

On a really good day, this design cycle (not including subsequent program test and debugging) took about an hour. The Intel MDS with its floppy disk drives and CRT screen editor shortened it to just a few minutes, not including the time it took to burn an erased EPROM, addressed in high-memory, that we finally used for program storage. Pretty primitive by today's standards, but cutting-edge technology for our little lab in the 1970s. Not to mention we had a hell of lot of fun.

By this time I had designed and had manufactured locally some sixteen static memory boards, each with one kilobyte of static RAM. I didn't know how to use dynamic RAM at that time, but sixteen kilobytes of RAM out of a 64 kB addressable memory space just seemed like a lot of memory to me at the time. The sponsor of the project asked me how much memory we would need, and off the top of my head I told him sixteen kilobytes should be more than enough. Even using 16-bit counters for the photo-electron count data would still leave 8 kB for data storage. By then I knew about EPROMs and figured we would use a few of those for program storage. We were going to display the stored counts on an x-y addressable CRT, but not a raster-scanned CRT. That came years later after I had graduated and was hired by a company heavily into digital image processing. It was amazing how rapidly raster scanning replaced vector displays. Many of our customers resisted this transition, but there was never any doubt (at least in my mind) that high-resolution raster displays would eventually replace all vector CRT displays. Today, I doubt you can find a vector CRT display anywhere.

Your comment about binary counter-addressed EEPROMs brought back some memories. I hooked up an A/D converter to the sine-bar drive mechanism of a Czerny-Turner Monochrometer to obtain wavelength information. The A/D converter output then addressed a static RAM array, into which the user had downloaded transmission information as a function of wavelength for the monochrometer. This data was used with a Burr-Brown hybrid multiplying four-quadrant D/A to linearize the response of a photo-multiplier tube that "looked" at the monochrometer output.
 

Wiginometry

Nov 29, 2017
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You guys make me wish i had a darn time machine. Dont get me wrong I know the horrors of watching your tech go the way of the dodo. At the same time though you actually got lucky or maybe unlucky enough to witness history happen faster than you could keep up with it. Most of my life when i might have gotten to witness it I was stuck in the backwoods so a lot of it passed me by.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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... a lot of it passed me by.
A lot of it passed us by, too. I don't remember when it happened, but somewhere between now and way back then, technology advanced faster than any single human being could possibly keep abreast of it. We all had to become specialists, knowing more and more about less and less. I fought this, but it was a losing battle. No one wants to hire a wannabe Renaissance Man. Employers have very particular requirements for the pegs they need to fit their holes. You learn to adapt your shape to fit, or you become unemployed.

I still try to keep up with a broad array of subjects, and it's a big waste of time. I might as well enjoy my retirement instead. But curiosity is a strange thing that knows not rational behavior, so on occasion I must "un-retire" to pursue my curiosity.

@Wiginometry you ain't seen nothin' yet! Nor have you missed anything that's important now. The next fifty years will be absopositively amazing. Try to survive long enough to see it! And enjoy the ride.

73 de AC8NS - Hop
 

Wiginometry

Nov 29, 2017
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Don't think I'll have any choice but to survive it.
ill be forced to regardless.

*This is about how it'll go for me*
Hey sarge the enemy blew off my limbs can I get you to sign my form so I can die without courtmarshal.... no... But I'm bleeding out sarge... No no no I'll use my tounge to pull the trigger.
(Or the wife will tell me I'm not allowed to either way I'll be kicking long after death has pulled my number)

Should be fun!
 

FuZZ1L0G1C

Mar 25, 2014
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three dits, three dahs, and three dits all sent as one symbol.
Wow! I've just learnt something new re the SOS distress code.
When doing signals with the Naval Cadets c. 1970's, we all presumed the characters were separate.
I've also been playing around this idea using Profilab Expert Simulator.
30 bit-width reduces gate-count.
Thanks for share. :)
 

Gumby_Kevbo

Jan 25, 2018
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Going back to the early W9TO vacuum tube keyer, there is a trick that may be useful:

If you have a 50% duty cycle multivibrator, that will run out a string of dots.

If you have a latch that holds the output on between two dots, you get a dash.

This rather cuts the problem in half, because now you only need the dot clock, and a way to bridge between pairs of dots when you want to make dashes. The 'TO keyer used a pair of triodess set up as a R-S latch which got reset when the second dot started.

The old IDers used on repeaters would use a counter driving a decoder that would drive the rows of a diode matrix. Diodes would be added between the rows and columns to configure the callsign.

Interesting aside:
In the early 1970s a fellow named Ronald Stordahl started selling a keyer kit that used logic chips instead of the tubes of the old 'TO keyer. These didn't sell too well, and he ended up with a bunch of left-over components. He started selling these mail order in order to cut his losses. This venture eventually became the company we now know as DigiKey!
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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I do believe that we just gained a new and sure to be valuable member.

Welcome aboard Gumby.

Chris
 
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