The 555 Has Been Around at Least 30 Years

The 555 was designed by Signetics sometime around 1971 and I had the original data book until 1998 when during a move to new premises I threw away most of the old stuff. I still got some of the ICs marked NE555N in my "linear" draw.

It's like hacking TV, fun to do, good results but never time to watch it. Not that there is anything to watch anyway.

You can allways use it to time your boiled eggs.

I used 555's in a project at work many, many moons ago. Had to be in '72 or '73. The 555's were wired monostable, controlled some voltages and signals to a PROM (Poccles(sp?) Readout Optical Memory) cell. Interesting device. A PROM cell is to an optical image what a latch is to a binary bit. Ultimately my device was hung on the busines end of the reflector telescope at Kit Peak Observatory to record images of .......???? I never knew.

wrote in

noticed

out

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NE555N in my

ISTR that the real original '555 was the winning submission in a US circuit design competition as to what you could do with a "linear array" semi-custom chip (Exar?).

Regards Ian

Best regards, Spehro Pefhany

Neat link, that jogged a few brain cells back into action. IIRC, there was some confusion when other manufacturers started copying the chip. Something about the formulae for calculating the timing being different depending upon whose datasheet you examined. Odd, considering that they were exact copies.

School project 1983, UC Berkeley, I designed and built a 'drunk disabler' using a 556. It was a series of 10 buttons, with LEDs over them. It had used a 556 and a couple of counters, if I remember correctly. The system would flash the LEDs in pseudo random order, and you had to push each of the buttons within a certain time limit (generated by the venerable 555) or the "Lockout" red LED would come on, and the test would fail. You would have to reset it then. If you were able to follow the buttons successfully for 16 different random LEDs, the "Success" green LED would come on. The idea was to be able to lock drunks out of their cars, of course.

I waited till the last minute to build it, and was up all night debugging it. It was the final lab project for a computer architecture class. I brought it in and, due to my lack of sleep, was unable to get the green light! The teaching assistant, and about 5 different students tried it out (there was a big crowd around it, it was like a video game, everybody wanted to try it out.) They were all failing it (the buttons sucked, but they were cheap.) This was a test, so they gave you 15 minutes to make a project work, as I recall. The TA was ready to flunk me until I manged to beat it after a few more tries. A cheer went up...

Regards, Bob Monsen

Some years ago I made a "cross pulse" monitor with some 555 timers

What is a cross monitor? well all I had to do was to break the Horizontal & Vertical sync inside the TV and delay the horizontal sync by half a line & the vertical by half a frame, it made the picture look like shit.

All jokes aside, when you played a VCR and the back tension was normal you got | _|_ | |

But if the back tension on the VCR was wrong you would get something like

| _|_ / |

I needed four 555 altogether, the only problem was the color went in and out of sync, but it was not for watching TV anyway,

Oh sorry if you are confused the ?|? represent the horizontal sync pulse and the ?_? represent the vertical sync pulse.

: Some years ago I made a "cross pulse" monitor with some 555 timers : : What is a cross monitor? well all I had to do was to break the Horizontal & : Vertical sync inside the TV and delay the horizontal sync by half a line & : the vertical by half a frame, it made the picture look like shit. : : All jokes aside, when you played a VCR and the back tension was normal you : got : | : _|_ : | : | : : But if the back tension on the VCR was wrong you would get something like : : | : _|_ : / : | : : I needed four 555 altogether, the only problem was the color went in and out : of sync, but it was not for watching TV anyway, : :

In article , snipped-for-privacy@interlogDOTyou.knowwhat mentioned...

Heh, great story, seems full of twists and turns. All sorts of nagging questions like, why did he quit and then come back? One would've thought that the 555 would've come first, since it seems simpler than a 565. After Signetics found out how popular the 555 was and how much money it made for them, you'd think they would hire him back on and keep him from selling his designs to other companies. But then who ever said that businesses were smart and did the right thing. Same as The Woz and HP. But if they had've, Forrest Gump wouldn'r have had that line about buying stock in some fruit company. ;-)

I recall when I first saw data on the 555, about 1965. The price was $150.00 .. This was in a some electronics magazine. or maybe a Poplar Science type magazine. Warren

In article , snipped-for-privacy@hotmail.com mentioned...

I don't eat eggs. :-P

As the weatherman predicted, it's raining here in So. Calif. The scary thought is, what's going to happen to all those thousands of acres of burnt hillsides. Are they going to turn into lahars?

Burning of heath and wood land is a normal part of the life cycle. It is preventing the regular occurrence of small fires that leads to dangerous brush buildup and huge, uncontrolled fires. My bet is that green shoots will be showing within a couple of weeks, and this time next year you will have a fine new cover everywhere. As for a lahar - why would you expect that?

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I've read about Kerr cells, but I don't remember anything about Pockels cells. When you sey business end, do you mean the eyepiece end? I've seen where the scientist takes two negatives for an image of the same section of sky taken at different times. He then puts them on a light table and switches the light between them, looking for differences in the two images. Stars and galaxies don't move so they don't change on the images. But planets, asteroids, comets, and the like can be seen in different places in the two exposures.

Maybe this pockels cell was used to switch the optics of a beam splitter or something like that. Nowadays the old photograpy methods have been replaced with sensor arrays like the ones in digital cameras.

In article , snipped-for-privacy@BulkingPro.com mentioned...

ROTFL! Hey, it almost got renamed from a 'drunk disabler' to a 'student flunker'!

Hey, I was almost bumfuzzled by a button today. I checked out a district vehicle today, a Dodge caravan van. I was stopped at a stop sign and I noticed that the two dome lights, above the windshield and rear-view mirror, were on. I didn't turn them on, they must've been on since the last person used the van yesterday. I looked for a switch button, around the lights, on the dashboard, etc., but I couldn't find one! So I forgot about it until I pulled in at the end of the day, when I again looked all over for a switch but with no success. I thought that maybe they were disabled by a timer after the ignition went off, but they still stayed on for the few minutes that I waited. Finally out of desperation, I tried to take the glass cover off to remove the bulb, and when I pressed on the glass, it turned off! Damn! I couldn't believe it!

A few years ago in the UK (and europe) they made it illegal for farmers to burn, they have done this once a year for ever. Now the whole of the country is in a state where if a fire starts then it burns for months instead of burning itself out in a few days. This situation is going to carry on getting worse. Another example of the wonderful centralised government that we seem to be building for ourselves.

In article , snipped-for-privacy@pearce.uk.com mentioned...

Actually they wouldn't be volcanic ash, just rivers of ashes from burned brush and trees coming down the gullies.

The huge uncontrolled fires in the forests are being caused by the bark beetles, which killed the trees weakened by the drought. Those dead trees, which are normally evergreen, turned into giant torches. That certainly is _not_ a 'normal part of the life cycle"!!

I think we must allow bugs to be part of the natural cycle. And of course one of the results of the burn is that the bugs are gone - so you get a whole clean new growth.

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Mudslides and flooding are also part of the natural cycle- you want to let them take their course too?

Best regards, Spehro Pefhany