For amusement

Or you can do it with exactly one triode.

Ah, progress!

Tim

-- Deep Friar: a very philosophical monk. Website:

Probably.

I do own the whole set of Tektronix of TV measurement manuals, from the '60's ;-) ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Thats good, because National just stopped making the LM1881

:-(

I did a lot of field sequential and split screen stereo video work using LM1881

RIP LM1881

Steve

I've always used LM339, since the '70's, but more complicated than this latest rendition. The CMOS design job tweaked my thoughts and then I saw the LM339 simplifications. ...Jim Thompson

Digikey still has a thousand. Might be a good inflation protector if there is a spare parts market for sync separators :-)

I've used it once myself but usually I did sync separators in discrete and jelly-bean parts. I do not trust chips for the TV and radio markets much. All it takes is one major VCR or whatever manufacturer jumping ship and ... chop.

It was introduced in the late '80s and on the market for 20 years.

Not a very long time. Some of my designs run longer than that in production.

So? The LM1881 outlived the demand, and is obsolete. Sony made a similar part at one time for their TV cameras.

In the past week I posted a trivial solution using LM339's. ...Jim Thompson

A similar circuit was floating around in the early '80s to convert TTL monochrome monitors into composite. A PC board & kit of parts was $7 including the 10 position edge connector. The LM1881 and Sony chip were used in cheap vidicon cameras.

Next he will be bitching that National dropped the MM5321.

production.

I figured out the full crack for cable encoding... then I realized there was no reason to bother... no material worth watching ;-) ...Jim Thompson

production.

...not even the Alpo dog food commercial? I think, of all of the commercials, that one was the _best_.

production.

The first 'scrambling' I encountered was the jamming signal in the TV channel's guard band. A tunable L/C notch filter got rid of that. It was overloading the distribution amps at some of the schools I serviced. The strange thing was that the old metal cased B&W Zenith school TVs already had a tuned trap in the guard band, and all it took was careful tuning to eliminate the jamming. My filters were a pair of parallel tuned traps, with a serial tuned trap to ground between them.

Years later I installed, programmed and calibrated a 'Hamlin' system. What a piece of crap.

production.

My first encounter with TV scrambling was subscription ON TV (over-the-air UHF). It used a superimposed gain-riding 15.75KHz sine-wave.

Apparently their engineers were sufficiently lacking in talent that the distributed boxes used only a coarse "one-over" compensation, resulting in recovered pictures having light edges.

My perfectionist personality created a circuit that was exact, so my picture quality was better than that of the paying customers ;-)

About one week after I had it working, ON TV went belly-up :-(

Then came suppressed sync. Trivial for an engineer if you just watch the signal with a 'scope for a while... solution jumps right out at you.

I would gather that present day cable boxes are more exotic, but there's nothing on cable worth the effort to crack it ;-) ...Jim Thompson

production.

Two weeks before Ch. 64 (WIII) shut down their ON TV in Cincinnati, Mendelson's (a huge electronic surplus dealer in Dayton) sold two tractor trailer loads of new & used On TV boxes, antenna kits and extra hardware at the Dayton hamfests. Guys were buying pallets of them for $1000 each while dreaming of the money they would make after modifying them. :)

Even easier on a video waveform monitor where you can select individual lines of NTSC video. I have a Tektronix RM529, and the HP clone that were made for the CCU consoles at TV stations. :)

There's nothing on TV worth watch, other than local news & weather. It's supposed to be cold again for the next few days, so I'll watch the pile of DVDs that I haven't seen. I picked up the entire original 'V' TV series for under $10 a few weeks ago. Sometimes I enjoy watching bad Sci-Fi and idiot politics. :)