EEVblog #867 - The Search For The First TTL Chip - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: April 06, 2016, 04:28:42 am
content: Can Dave find the first mention of TTL chips, on the 50th anniversary of TTL?Some old resurrected footage and a segment idea from July 2014, Welcome to Wayback Wednesday, were Dave looks though his old Electronics Australia magazine collection.

author: gnavigator1007
author_rank: Unknown
timestamp: April 06, 2016, 05:53:31 am
content: This segment was awesome. Too bad about the recording issues. I love seeing the old magazines and thinking about what it was like and what has changed since. Seems like a lot of work digging through your collection. Reminded me a bit of a public television show we have here in the states called History Detectives. Hope you will do more of these

author: TheSteve
author_rank: Unknown
timestamp: April 06, 2016, 06:00:42 am
content: I love the history of electronics. I'd certainly be up for more videos. Just for fun I had a quick look through some TTL chips I was given years ago, the oldest I have in stock is a 7483 with date code 7205(older then me!).

author: amspire
author_rank: Super Contributor
timestamp: April 06, 2016, 06:30:47 am
content: I seem to remember that in the 60's, the yeild problems that TI was having with the 74 series was pretty bad. A 20% yield was good, and they had to run several fabs, because it wasn't uncommon for a single fab to loose the magic. The silicon wafers were pretty small then, so there were not a lot of chips on a wafer. I think I remember still reading of yield problems in the mid-70's. There was much more seat of the pants work and tweaking back then.It took a while for TTL to get cheap enough to use instead of discrete diode-transistor logic for the hobbyist. The first time I got my hands on any 74 series chips was in the early 70's.Definitely, those Fairchild RTL IC's were much cheaper, and also they could be used in analog circuits. They would have been the first ICs I ever used. The next would have been the Fairchild uA702 Op-amp. 3 power rails and if the inputs went outside the +/-5v common mode range, they would blow. The first ones I got would have cost the equivalent of about $30 in today's money. But it had a 30MHz bandwidth - pretty good for the first common opamp. 0.5mV offset. 2uV/C drift.Buying these kind of parts in Sydney wasn't hard. George Brown used to be in Kent street, and I was able to get there after school.Richard

author: bktemp
author_rank: Super Contributor
timestamp: April 06, 2016, 06:40:52 am
content: Great video.Just an idea to add some extra features in the video series (if you plan to continue):Since a lot of people watching the videos are much younger, they have probably never heard of DTL, tunnel diodes, tubes and other obsolete stuff. Maybe you could add some breadboard scenes experimenting with the parts shown in the magazines, like at the end of Fundamental Friday. Many parts are probably hard to find today and maybe too exensive, but it would be great to preserve the information for younger people in a nice video.

author: Brumby
author_rank: Unknown
timestamp: April 06, 2016, 08:19:59 am
content: I know I still have a couple of tubes of 7400 chips (circa 1980) - 7400, 7404 and some others...They're in a box ... somewhere.

author: German_EE
author_rank: Super Contributor
timestamp: April 06, 2016, 09:09:11 am
content: As a schoolchild I remember finding an issue of Practical Electronics that had a digital project in it. This also used modules rather than 0.1 inch DIP chips, it would have been about 1972. maybe 1973.As for the video, more please, there's nothing wrong with a bit of history. Maybe then the 'young players' will appreciate how far we've come.

author: grouchobyte
author_rank: Regular Contributor
timestamp: April 06, 2016, 10:30:37 am
content: Hell, I not only have some DTL and RTL stuff like Fairchild 914 and 923's (JK flip flops) I have designed with them. I even designed an analog computer board with 2n107s and 741's for money.http://semiconductormuseum.com/MuseumStore/MuseumStore_Fairchild_923_Index.htmAh, those were the days. Those parts are not only outdated by todays standards, good old yours truly is no spring chicken either.Speaking of old, here's a guy I meet at a local bakery and sit across from at a common table and have coffee with every so often, in fact just last Saturday. He is 93 years old. Talk about crusty. This guy invented the pixel. Google him....Russell Kirsch. Unfortunately, he has advanced Alzheimer's and talks ad nauseum about his NIST achievements never remembering conversations that occured previously.http://www.nist.gov/public_affairs/releases/image_052407.cfm@grouchobyte

author: EEVblog
author_rank: Unknown
timestamp: April 06, 2016, 10:48:25 am
content: Quote from: bktemp on April 06, 2016, 06:40:52 amGood idea.

author: ftonello
author_rank: Contributor
timestamp: April 06, 2016, 12:31:42 pm
content: Old school have much to teach yet!. I Have several old school magazines in PDF (from 70´s to now - only in portuguese) that time to time i consult for design ideas. For interested Brazilians viewers and others, you can contact me and i´ll provide the links for my maganizes for free once i think this is public domain now, and that you not planning selling in the internet. They will recognize the images below.Of course, if permited by forum rules.

author: nixfu
author_rank: Unknown
timestamp: April 06, 2016, 01:10:25 pm
content: Dave, one thing that would be fun to me to make part of a wayback wednesday segment would be if you have copies of those issues, is going through YOUR old articles and projects that were in EA, and Silicon Chip.No one could explain the project in depth like you could and it would be extra fun for those projects which you still have the original prototypes to show as well.Just a thought.

author: nctnico
author_rank: Super Contributor
timestamp: April 06, 2016, 05:49:04 pm
content: Quote from: nixfu on April 06, 2016, 01:10:25 pmThis could be a good idea to bring up some good old analogue circuit engineering.

author: station240
author_rank: Unknown
timestamp: April 06, 2016, 06:04:20 pm
content: Most interesting part was the Fairchild FuL 900 series being 3.6V. I had no idea we had <5V logic back in 1966.Could be interesting to see when the first 3.3V logic ICs came out.Being in SA I just had to look up Texas Instruments Oldham road elizabeth SA. The road is right opposite Holdens (car plant).I did find a job ad ( Sydney Morning Herald, Saturday, July 3, 1965, Page 80 ) that says:"Since commencing  in Australia in 1959, the Company has expanded operations considerably In the manufacture of specialised engineering products, Including Non Ferrous and Ferrous thin gauge metal strip and  controls.""The parent Company is a world leader in semi-conductors and electronics, as well as in specialised metals and controls"Also states SA was the head office.The buildings all look like generic factory buildings, so no idea which one was TI.

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 06, 2016, 06:14:29 pm
content: Ironically the first thing I built with the 7400 series was analog, using one 7404 hex inverter. Two inverters to make a 1KHz tone, another 2 to modulate that with a .5 Hz frequency to make 2 tones, and the last 2 inverters to get a 27MHz crystal oscillating (probably on the 9MHz fundamental). The little bug could be heard up into the FM band within a distance of a few 100 meters.

author: Howardlong
author_rank: Super Contributor
timestamp: April 06, 2016, 08:39:30 pm
content: This is the oldest I have at hand, a 74153 date code 7024.Not sure what my first chip circuit was but if I were to bet it would've probably been a 7400 as an SR flip flop. We used to use those old 6V lantern batteries with springs on the top for our 5V power supplies. Making a 5V power supply was luxury, usually a single PNP emitter follower like MJ2955 with zener on the base optionally as a darlington. The regular common currency was the LM309K but that was expensive.

author: richfiles
author_rank: Regular Contributor
timestamp: April 06, 2016, 09:17:19 pm
content: I got a kick reading about the neon logic. I have six of the decade counter/nixie tube display boards from an old ANITA Mk7 (from around 1961). Really cool bit of vintage kit. Wish I had the real deal... A working, complete calculator. Oh well, maybe someday.

author: nctnico
author_rank: Super Contributor
timestamp: April 06, 2016, 09:26:46 pm
content: My first ventures into digital chips where the 4000 series CMOS logic chips but I have also built complex circuits with just 74LS series chips. IIRC one was a smart stepper motor controller with pull-in and pull-out (feed it the number of steps and toggle a line to make it go).

author: mark-r
author_rank: Contributor
timestamp: April 06, 2016, 09:47:29 pm
content: I have one of the Mullard circuit blocks that were in that advert, an FF12 flip-flop. I've also attached a section of a Philips/Mullard databook showing the circuits.

author: SL4P
author_rank: Super Contributor
timestamp: April 06, 2016, 10:12:30 pm
content: I was very young (around 14yo), and had the privilege of being invited to the studio recording of a 'Faraday Lecture' in Sydney. The subject was exactly this - Integrated Circuits.This was probably 1970 - in Australia's first fully colour equipped studio facility (VTC), and had maybe thirty people in the audience, with two on-camera engineer/presenters from the UK, with a couple of demos of the fundamentals - and the ability to create relatively complex, high-speed circuits before our eyes.(IIRC, one was measuring the travel time of a light beam across the room)Fantastic to watch and reflect back in how far we've come!

author: rolycat
author_rank: Super Contributor
timestamp: April 06, 2016, 10:21:47 pm
content: Quote from: Howardlong on April 06, 2016, 08:39:30 pmI think I can (just) beat that with this humble 7400 from 1969:(Yes, it still works.)The manufacturer took a little finding. Who remembers Transitron these days? They went bust in 1986, but apparently in 1961 they were number two in America after Texas Instruments.

author: jh15
author_rank: Frequent Contributor
timestamp: April 06, 2016, 10:34:53 pm
content: I worked in an oem manufacturing plant for Bell System products in the 70's and used to unsolder dtl DIPs from scrap boards to take home and learn from. Even in my sort of teen years there, i used cloro cleaning liquids to cool them, but thought I'd be old before it affected me... So is why I watch EEVblog vs binging on Netflix now, I guess. My wife worked in Bell Labs.The dtl chips, which I'm sure I have, were sort of shiner and hard, and rounder compared to the typical 7400 package.fun stuff, keep it up.

author: nova1200
author_rank: Contributor
timestamp: April 06, 2016, 11:37:13 pm
content: Great video. My oldest is this 7474 from 1968:Also have several tubes of 7400's from early 1969:

author: Stephen Durr
author_rank: Contributor
timestamp: April 06, 2016, 11:49:36 pm
content: Good stuff. I would like to see more way-back videos.

author: Brumby
author_rank: Unknown
timestamp: April 07, 2016, 12:39:38 am
content: Sigh.Now I'm going to have to look for my 7400 series tubes ... just to find out the date codes.

author: coppice
author_rank: Super Contributor
timestamp: April 07, 2016, 04:01:16 am
content: Quote from: station240 on April 06, 2016, 06:04:20 pmMost, if not all, RTL parts were 3.6V. I'm not sure why all manufacturers settled on exactly the same voltage, since they were not producing second sources of each other's parts.

author: linux-works
author_rank: Super Contributor
timestamp: April 07, 2016, 04:09:47 am
content: Quote from: grouchobyte on April 06, 2016, 10:30:37 amthe first chips I had to play with, as a kid, were DTL dips that my older brother gave me. 846 and 848 or something like that; some NAND and some flip flops. I didn't get actual ttl chips to play with until years later, when I hit my teen yearsI will have to search for those old chips. I think I still have them after all these years. I would not have thrown them away, that much I know.

author: snoopy
author_rank: Frequent Contributor
timestamp: April 07, 2016, 07:31:50 am
content: When is Silicon Chip going to archive all of the copies of ETI, EA onto DVD ? Their excuse of Copyright is pretty lame if you consider that 25 years takes you back to 1990 so anything before that should be made available to the public without any legal repercussions. Maybe they can offer Vol 2 in addition to their current archive DVD of RT&H.http://www.siliconchip.com.au/Shop/5/2950cheers

author: SL4P
author_rank: Super Contributor
timestamp: April 07, 2016, 08:45:36 am
content: or the cost-benefit of scanning, cataloging and publishing that extra content may just 'not be viable'.

author: Kjelt
author_rank: Super Contributor
timestamp: April 07, 2016, 08:59:23 am
content: were these 74 chips from the start on always in plastick packages, never in ceramic ?I actually used mainly the 4000 cmos series and I have a lot of old ones in those great ceramic packages.

author: Fungus
author_rank: Super Contributor
timestamp: April 07, 2016, 09:21:13 am
content: Quote from: wilfred on April 07, 2016, 08:42:23 amIf the magazine paid people for articles they might own the copyright, not the authors.Who knows?

author: coppice
author_rank: Super Contributor
timestamp: April 07, 2016, 11:08:39 am
content: Quote from: Kjelt on April 07, 2016, 08:59:23 amEarly on there were 74xx parts in both ceramic and plastic packages. There were also 64xx parts with an intermediate, industrial type of temperature range, which were all ceramic packaged parts. They disappeared pretty quickly. I don't think anything rated for >70C came in a plastic package in those days.SN54xx parts are not actually mil spec. They are just mil temperature range. The real military and space qualified parts had longer names with 54xx buried somewhere in the middle. There were two or three levels of qualification, manned space flight being the highest. It so long since I touched this stuff I can't remember all the details.

author: Howardlong
author_rank: Super Contributor
timestamp: April 07, 2016, 11:30:04 am
content: Quote from: linux-works on April 07, 2016, 04:09:47 amI used to mix and match the DTL chips with TTL, as I remember they were compatible with each other in terms of inputs and outputs, but I can't remember if they were pin compatible.A couple of years ago I was debugging a bit of old aviation DME equipment from the mid 70s, that had some 900 series RTL in it. I have to say that it was a project I never completed: despite having the service manuals for it, the problem was intermittent and I didn't really gave the right test equipment. DME is reasonably high power half duplex L band stuff, the RTL PLL wasn't consistently locking, but without the right TE (or access to a real DME ground segment) and as it's a dynamic bidirectional system, it was pretty hard to debug and test. One day...

author: lapm
author_rank: Frequent Contributor
timestamp: April 07, 2016, 02:52:02 pm
content: Just love wayback video.. Sometimes you learn something new like those neontube logics, newer before even heard of such things...

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 07, 2016, 03:17:11 pm
content: With enough work you could do a two layer wayback. I remember an article from the 1960s called the girl detector, intended for frat houses and the like. It generated a wolf whistle when presented with the appropriate gender. I think it was in the US magazine Popular Electronics, and it was a transistorized update of a much earlier vacuum tube circuit. The fundamental idea wouldn't work today. It was an infrared sensor that detected the temperature difference between someone wearing a skirt and trousers, so wouldn't be a reliable sexer today.

author: Svuppe
author_rank: Regular Contributor
timestamp: April 07, 2016, 03:18:38 pm
content: Why talk about TTL from the 60's, when CMOS was available in the 50'sNo, of course they weren't, but what was this "date code" used for then? It obviously isn't a CMOS package from 1956.

author: coppice
author_rank: Super Contributor
timestamp: April 07, 2016, 03:24:23 pm
content: Quote from: Svuppe on April 07, 2016, 03:18:38 pmNotice the National Semiconductors logo? They produced a series of CMOS devices beginning MM56xx. Most were pin to pin replacements for CD40xx parts, so many were dual labelled.

author: TinkerFan
author_rank: Regular Contributor
timestamp: April 07, 2016, 03:47:57 pm
content: For the Wayback Wednesday.For me as a "young player", it is really interesting to see, what was going on, when my father/grandfather was playing with electronics...

author: Lovely_Santa
author_rank: Contributor
timestamp: April 07, 2016, 03:52:18 pm
content: Quote from: TinkerFan on April 07, 2016, 03:47:57 pmI am 20 years old now, still student at the university and I am very happy to see this kind of stuff, very interesting how things work and evolve trough the yearsSo thumbs upfor more video's like this!

author: BravoV
author_rank: Super Contributor
timestamp: April 07, 2016, 04:05:42 pm
content: Are these TTL chip ?Gold plated pins , dual JK Flip-Flop (MC890P) and Hex Inverter (MC889P), found in my Tektronix 2901 Time Mark Generator -> (Teardown)

author: rolycat
author_rank: Super Contributor
timestamp: April 07, 2016, 04:32:35 pm
content: Quote from: BravoV on April 07, 2016, 04:05:42 pmI believe they are RTL (Resistor-Transistor Logic) chips, a predecessor to TTL which was introduced in the early sixties.More info on the MC800 serieshere.

author: coppice
author_rank: Super Contributor
timestamp: April 07, 2016, 05:12:03 pm
content: Quote from: BravoV on April 07, 2016, 04:05:42 pmThose are Motorola's RTL family. The MC7xx, MC8xx and MC9xx series parts were the same devices in three different temperature options. They were the first logic devices I used, and in about the same year yours are date stamped.

author: Howardlong
author_rank: Super Contributor
timestamp: April 07, 2016, 05:20:00 pm
content: To add (possibly confusion) note that not all MC8xx are RTL, there's a gap around 830-850 which are DTL.

author: SeanB
author_rank: Super Contributor
timestamp: April 07, 2016, 05:32:45 pm
content: Quote from: Svuppe on April 07, 2016, 03:18:38 pmWeek 5 of likely 1980, as it has the Nat semi logo they were using around then. This is the "cheap" cerdip package, made using a Kovar leadframe from the plastic DIP circuits, but with a ceramic base and lid, sealed with a fired cement after bonding. The more expensive versions ( the aerospace rated, these are just extended industrial parts) used a gold fired ceramic leadframe with side brazed leads. Those were expensive, and the testing on them made them even more so.

author: WattSekunde
author_rank: Regular Contributor
timestamp: April 07, 2016, 06:05:11 pm
content: I found these old RTL Logic Blocks called Norbit-S from Valvo. They are looking like huge DIL chips. I have to ask my dad but I guess they are from the late 60's.The "normal" sized Siemens FZH101 is from 1974.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: April 07, 2016, 08:25:39 pm
content: Quote from: Kjelt on April 07, 2016, 08:59:23 amFrom my collection (none are extremely old):Attached is a photo of a Signetics 74164, with a date code from 1973, in a ceramic DIP (along with a ceramic LM555).Also attached are photos of 5400 parts in a TO-86 ceramic flatpak (surface mount) package, along with the plastic carriers that they were shipped in. Two are a 5400 and I believe the other is a military labelled 5450 expandable dual 2-wide 2-input and-or-invert gate.

author: snoopy
author_rank: Frequent Contributor
timestamp: April 07, 2016, 11:05:55 pm
content: Quote from: wilfred on April 07, 2016, 08:42:23 amSo how do they get away with selling their existing DVD which covers everything up to and including Radio Television and Hobbies before it changed name to Electronics Australia which was around 1967 or there abouts ?cheers

author: timb
author_rank: Super Contributor
timestamp: April 07, 2016, 11:49:17 pm
content: Quote from: CatalinaWOW on April 07, 2016, 03:17:11 pmPopular Electronics January, 1964 (Starts on Page 33)It was part of the "Carl and Jerry Adventure in Electronics" series. They used a thermistor, not an IR sensor. (I don't think IR was even commercially available yet in '64, was it? LEDs would have been in their infancy; if I recall right, HP Labs was having major problems with their production for several years. They didn't really get the process down until '69-70.)Also, the American Radio History site has a large archive of old electronics, radio, TV and computer rags in PDF form. You can find some neat projects in them.http://www.americanradiohistory.com/index.htm

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 08, 2016, 12:55:40 am
content: Quote from: timb on April 07, 2016, 11:49:17 pmThat is the article I was talking about. Thanks for digging it up. And the thermistor was the IR sensor. Now we are just arguing about specs like speed and sensitivity. Somebody thirty years from now will be arguing that IR sensors (resistive bolometers) weren't available much before 2005.

author: coppice
author_rank: Super Contributor
timestamp: April 08, 2016, 03:59:32 am
content: Quote from: MLXXXp on April 07, 2016, 08:25:39 pmAlthough a number of defence contractors eventually formed the legs of flatpack devices, and surface mounted them, they were not intended to be surface mount devices.

author: Kjelt
author_rank: Super Contributor
timestamp: April 08, 2016, 08:05:15 am
content: Quote from: MLXXXp on April 07, 2016, 08:25:39 pmThanks for sharing, very interesting, never knew/saw that they were packaged individually. Are those plastick carriers ESD safe? They don't look like it.

author: coppice
author_rank: Super Contributor
timestamp: April 08, 2016, 08:27:36 am
content: Quote from: Kjelt on April 08, 2016, 08:05:15 amI think they should be ESD safe. The earliest plastic tubes for DIP packages were, so the semiconductor makers took that issue seriously from the early days. People assembling boards, on the other hand.......

author: Brumby
author_rank: Unknown
timestamp: April 08, 2016, 08:45:33 am
content: Don't know about other chip families, but the 7400 series had a fairly low input impedance. IIRC an output only had a fan-out of 10.ESD didn't really become a big thing until CMOS came to town.

author: richfiles
author_rank: Regular Contributor
timestamp: April 08, 2016, 09:00:17 am
content: I don't recall the exact logic type, but the Victor 3900 calculator used around 30-ish very early LSI chips (about 250-300 P-channel MOS transistors per chip). They were slated for a release in the summer of 1965, but were delayed to october when they discovered ESD was blowing their calculators up. They mitigated a lot of the risk by bodging resistors into the design, but the chips themselves were inherently vulnerable, as they simply didn't have internal ESD protection.I have to imagine the industry had become WELL aware of ESD risks around that time period!

author: MLXXXp
author_rank: Frequent Contributor
timestamp: April 08, 2016, 02:07:10 pm
content: Quote from: coppice on April 08, 2016, 03:59:32 amI've only seen a few photos of flatpacks actually soldered to circuit boards. As best as I can recall, they had the leads bent down for surface mounting, as described in these articles:http://firetrucksandequipment.tpub.com/TM-9-254/css/TM-9-254_135.htmhttp://www.tpub.com/neets/book14/59f.htm(scroll down to near the end)How were they originally intended to be mounted?

author: Svuppe
author_rank: Regular Contributor
timestamp: April 08, 2016, 02:08:32 pm
content: Quote from: SeanB on April 07, 2016, 05:32:45 pmOh, so the 3-digit number is a date code. Never would have guessed that myself.

author: rrinker
author_rank: Super Contributor
timestamp: April 08, 2016, 02:19:46 pm
content: Yeah, you see the older 3 digit date code a lot in older equipment teardowns. I guess in the early days they weren't thinking about the same part continuing across decades. Not just a Y2K issue.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: April 08, 2016, 02:23:27 pm
content: Quote from: Kjelt on April 08, 2016, 08:05:15 amI can't say for sure. I have no way to test them. My guess is that they aren't ESD safe. At least in my experience, there wasn't much concern about ESD with TTL devices back then, mostly only for FET transistors and CMOS chips. However, as has beenpointed out bycoppice, other ESD safe packaging was being used at the time, so these carriers could be.

author: coppice
author_rank: Super Contributor
timestamp: April 08, 2016, 05:25:32 pm
content: Quote from: MLXXXp on April 08, 2016, 02:07:10 pmWe did that for airborne electronics, but you can't do that for missiles. The G forces are too high, and components would rip off the board.Quote from: MLXXXp on April 08, 2016, 02:07:10 pmI believe flatpacks were originally developed for the minuteman missile. Try looking up the electronics in that, designed to operate at enormous G forces.

author: SeanB
author_rank: Super Contributor
timestamp: April 08, 2016, 06:22:37 pm
content: Flatpacks were intended to be spot welded to the PCB, and then conformal coated to hold them down physically. They were formed and soldered as well, and with this and a conformal coat ( a wide range of them, both solder through or remove totally before soldering) they were very popular as a way to get the size of a board down to fit a box envelope.Beware that the pinouts of the flatpacks are NOT the same as the DIP versions, the power pins are in the middle, and not the common pin 8/16 or 7/14 as on the rest of the TTL family.There were a few missile designs where the flatpack devices were bonded to a flexible PCB and then selectively conformal coated to protect the pads ( using a flexible coat) and then the whole lot was rolled up in a jig to fit the space envelope, and placed in a mould and then further potted in a solid resin, making a final structural part that had electronics, capacitors and such all in a cylinder that contained other missile structure. Low failure rate there, mostly from actual physical damage breaking the structure.Still have the special Weller Flatpack tip I bought, and it is in a Solomon handle now. Made changing the failed flatpacks a 5 minute job, instead of the 30 minutes otherwise using a stainless steel wire and stripping each lead off the pad individually. Yes the plastic holder, you get 3 types, the ones illustrated, another with a 2 part clip together package and the third with the leads rolled around a bar to lock the pack in place. They are all a static dissipative plastic, though the insulation was measurable in Mohms, as you had a test jig you could simply place the whole package in as is, and it broke the leads out to a larger DIP pattern for insertion into a breadboard or an ATE system, so you could do a parameter check on the IC you were installing. Very fiddly trying to get 16 grabbers onto the leads otherwise without twisting them, and a twisted lead was a pain, as you could easily pop off the lid in trying to bend it straight, especially those in the top section. They did come in both ceramic hermetic with lids, ceramic with a glass frit seal, ceramic with side brazes ( only the larger number of pin packages though for MSI, which were almost a PLCC part with leads) and plastic moulded packages.Strangely enough you get a modern adaptor that takes the flatpack, or a modern SMD part, and converts it to the DIP form, but with a sealed package. This is a compatibility part to replace old obsolete DIP parts with more modern SMD or old production flatpack parts, where you do not want to respin the board ( or certify it really ) to keep old things in military and aerospace running. There are even 24/28/40 pin adaptors with the inside being a FPGA and memory or an ASIC to replace obsolete DIP parts. Where else will you get a pin compatible new part to replace an obsolete 2708 OTP Eprom in equipment, and still have the same part interchangeable in the equipment. They were often used not as a memory but as an 8 input 8 output combinational logic block to replace a board full of TTL.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: April 08, 2016, 10:38:15 pm
content: Quote from: SeanB on April 08, 2016, 06:22:37 pmStill falls under the definition of "surface mount", as far as I'm concerned. Thanks for the detailed explanation of the use of flatpacks.The ones I have were from a cheap "grab bag" mail order fromPoly Paksor somewhere similar. I thought they might be useful for experimenting, even if I had to bodge them into something, since prime parts were expensive for me at the time.I never actually encountered any flatpacks in "real life".

author: rrinker
author_rank: Super Contributor
timestamp: April 09, 2016, 02:52:11 am
content: Somewhere I have a bunch of 7 segment LEDs that are in the flatpack format. I have no idea where I got them from, but now and then as I root through some junk boxes I come across them.My favorite (because it was my first computer) retro processor, the RCA 1802, has an unobtanium support chip, the 1861 'Pixie' graphics chip, a very rudimentary low res b&w graphics chip. A few different people have made substitute versions using a GAL or PAL (and one I think with a micro - though that may be a whole 1802 CPU) pin-compatible with the original 1861, so you can drop it in anywhere there was an 1861 and it works.This is getting a bit afield of the early 7400 series - well, I have some older TTL logic and some micro stuff (8085 I think) that I snagged from a forgotten Teletype terminal that was in the lab we used to build our senior projects in college. I'll have to check the date codes. Pretty sure most of it is no later than mid-70's.

author: Ampere
author_rank: Regular Contributor
timestamp: April 09, 2016, 03:30:10 am
content: Quote from: nixfu on April 06, 2016, 01:10:25 pmI'm all for this idea. I always appreciate the videos where Dave explains how something works. Fundamentals Friday and the power supply design series were my favorites.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 10, 2016, 01:40:41 am
content: Quote from: coppice on April 08, 2016, 05:25:32 pmHeh, even the Sprint's 100G acceleration looks sedate compared to an artillery shell and they were able to cram a tube radar/metal detector in there in WWII.Oh, and missiles don't spin at 20000RPM...

author: chris_leyson
author_rank: Super Contributor
timestamp: April 10, 2016, 07:01:41 am
content: Thanks Alex, nice pictureLooks like they replaced the battery electrodes with a piece of wood, I guess it's easier than trying to section dozens of thin zinc plates. Here's a close up photo of a Mk45 oscillator, the oscillator triode is mounted inside the coil former.Triode close up, you can just see one side of the grid winding and the "mouse trap" spring, right hand side above the anode, that keeps the filliament under tension when undergoing 100's of G acceleration.

author: chris_leyson
author_rank: Super Contributor
timestamp: April 10, 2016, 07:07:17 am
content: Oscillator section

author: SeanB
author_rank: Super Contributor
timestamp: April 10, 2016, 09:28:56 am
content: Also used to detonate the first atomic bombs dropped, though there they also had back up altimetric fuses and conventional timers as well. The proximity fuses were only armed after a certain time interval and once the bomb had dropped low enough, so as not to go off too close to the bombers dropping them.

author: bitwelder
author_rank: Super Contributor
timestamp: April 10, 2016, 05:39:28 pm
content: More thumbs up for the Wayback Wednesday!I think it would make an interesting segment for both young players (who haven't seen that stuff before) and old geezers (who are nostalgic about those times)

author: jh15
author_rank: Frequent Contributor
timestamp: April 13, 2016, 08:35:25 pm
content: I repaired I think it was the airspeed indicator for the 747s that had a flatpack 555 timerIt also had a unijunction transistor in it for a "clock" or maybe watchdog timer.Only other unijunctions I worked with were in Bell System oem equipment.I'm sure I have some from dumpster diving (not really, production girls knew I was a nerd and brought floor sweepings before hitting the floor. Example being parts with leads cut wrong, etc).

author: GeoffreyF
author_rank: Regular Contributor
timestamp: April 17, 2016, 09:35:29 pm
content: I was 15 by the end of 1966, living in New York City, USA. I remember those days the discussion in US hobby magazines turned on RTL mostly. Don Lancaster had a book on that with some projects. TTL was very expensive then, beyond most hobbyists. One might buy a chip to play, but that was it. I was working with TTL professionally about 1973. Later working at Digital Equipment Corp there was a corporate legend that the JK Flip flop was so called because it was invented by Jeffrey C Kalb, then a VP at DEC. What else to name the inputs but his initials? Indeed he holds patent US 3591856 for the TTL "J-K Master-slave flip-flop". That patent was awarded in 11/7 1967. The PDP 11/20 (the first model of the line) was all TTL, with some discrete transistors. The 11/70 the peak of that line was also TTL. The Vax 11/780 was mostly TTL still.I worked for the US Distributor of the EMS Putney Synthesizer as my first paid work with TTL. They had a capacitance touch piano keyboard and sequencer for their AKS Synthi which fit in an attache case. That device was all TTL with 1k Shift register memory. The Touch keys were done by allowing the inputs of 74150 chips to float, with some bias to keep them consistent. It was an out of spec use. Later versions of 74150 were "Too good" for that trick to work.

author: ornea
author_rank: Unknown
timestamp: April 18, 2016, 02:19:37 pm
content: Another thumbs up for the Wayback Wednesday!Thanks Dave for the uploading what you had, much appreciated.I spent hours thumbing thru my old magazines until the termites got them.